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Journal logoCRYSTALLOGRAPHIC
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ISSN: 2056-9890
Volume 72| Part 5| May 2016| Pages 704-708

Crystal structures of 4-methyl-2-oxo-2H-chromene-7,8-diyl di­acetate and 4-methyl-2-oxo-2H-chromene-7,8-diyl bis­­(pent-4-ynoate)

CROSSMARK_Color_square_no_text.svg

aDepartment of Chemistry, Howard University, 525 College Street NW, Washington, DC 20059, USA, and bDepartment of Chemistry, Keene State College, 229 Main Street, Keene, NH 03435-2001, USA
*Correspondence e-mail: lystranne.maynard@howard.edu

Edited by P. C. Healy, Griffith University, Australia (Received 12 March 2016; accepted 8 April 2016; online 15 April 2016)

In the structures of the two title coumarin derivatives, C14H12O6, (1), and C20H16O6, (2), one with acetate and the other with pent-4-ynoate substituents, both the coumarin rings are almost planar. In (1), both acetate substituents are significantly rotated out of the coumarin plane to minimize steric repulsions. One acetate substituent is disordered over two equivalent conformations, with occupancies of 0.755 (17) and 0.245 (17). In (2), there are two pent-4-ynoate substituents, the C C group of one being disordered over two positions with occupancies of 0.55 (2) and 0.45 (2). One of the pent-4-ynoate substituents is in an extended conformation, while the other is in a bent conformation. In this derivative, the planar part of both pent-4-ynoate substituents deviate from the coumarin plane. The packing of (1) is dominated by ππ stacking involving the coumarin rings and weak C—H⋯O contacts link the parallel stacks in the [101] direction. In contrast, in (2) the packing is dominated by R22(24) hydrogen bonds, involving the acidic sp H atom and the oxo O atom, which link the mol­ecules into centrosymmetric dimers. The bent conformation of one of the pent-4-ynoate substituents prevents the coumarin rings from engaging in ππ stacking.

1. Chemical context

Coumarins and their derivatives have wide applications in a number of diverse areas. They are used in the pharmaceutical industry as precursor reagents in the synthesis of a number of synthetic anti­coagulant pharmaceuticals (Bairagi et al., 2012[Bairagi, S. H., Salaskar, P. P., Loke, S. D., Surve, N. N., Tandel, D. V. & Dusara, M. D. (2012). Int. J. Pharm. Res. 4, 16-19.]), the most notable being warfarin (Holbrook et al., 2005[Holbrook, A. M., Pereira, J. A., Labiris, R., McDonald, H., Douketis, J. D., Crowther, M. & Wells, P. S. (2005). Arch. Intern. Med. 165, 1095-1106.]). Modified coumarins are a type of vitamin K antagonist (Marongiu & Barcellona, 2015[Marongiu, F. & Barcellona, D. (2015). Bioactive Nutraceuticals and Dietary Supplements in Neurological and Brain Disease, edited by R. R. Watson & V. R. Preedy, pp. 395-398. New York: Academic Press.]).

In another important application, coumarin dyes are extensively used as gain media in blue–green tunable organic dye lasers (Schäfer, 1990[Schäfer, F. P. (1990). Editor. Dye Lasers, 3rd ed. Berlin: Springer-Verlag.]; Duarte & Hillman, 1990[Duarte, F. J. & Hillman, L. W. (1990). Editors. Dye Laser Principles. New York: Academic Press.]; Duarte, 2003[Duarte, F. J. (2003). In Tunable Laser Optics. New York: Elsevier-Academic. Appendix of Laser Dyes.]). Coumarin tetra­methyl laser dyes offer wide tunability and high laser gain (Chen et al., 1988[Chen, C. H., Fox, J. L., Duarte, F. J. & Ehrlich, J. J. (1988). Appl. Opt. 27, 443-445.]; Duarte et al., 2006[Duarte, F. J., Liao, L. S., Vaeth, K. M. & Miller, A. M. (2006). J. Opt. A: Pure Appl. Opt. 8, 172-174.]), and they are also used as the active medium in coherent OLED emitters (Duarte et al., 2005[Duarte, F. J., Liao, L. S. & Vaeth, K. M. (2005). Opt. Lett. 30, 3072-3074.]).

4-Methyl coumarin derivatives have previously been used as acetyl-group donors for post-translational modification of proteins via an acet­yl–CoA independent mechanism (Raj, Singh et al., 2005[Raj, H. G., Singh, B. K., Kohli, E., Dwarkanath, B. S., Jain, S. C., Rastogi, R. C., Kumar, A., Adhikari, J. S., Watterson, A. C., Olsen, C. E. & Parmar, V. S. (2005). Pure Appl. Chem. 77, 245-250.]; Raj, Kumari et al., 2006[Raj, H. G., Kumari, R., Seema, K., Gupta, G., Kumar, R., Saluja, D., Muralidhar, K. M., Kumar, A., Dwarkanath, B. S., Rastogi, R. C., Prasad, A. K., Patkar, S. A., Watterson, A. C. & Parmar, V. S. (2006). Pure Appl. Chem. 78, 985-992.]). Calreticulin-mediated acetyl­ation of gluta­thione-S-transferase (GST) using substrate 7,8-diacety­oxy-4-methyl coumarin, DAMC (1) (systematic name: 4-methyl-2-oxo-2H-chromene-7,8-diyl di­acetate) has been shown to inhibit GST activity in a spectroscopic assay (Raj, Singh et al., 2005[Raj, H. G., Singh, B. K., Kohli, E., Dwarkanath, B. S., Jain, S. C., Rastogi, R. C., Kumar, A., Adhikari, J. S., Watterson, A. C., Olsen, C. E. & Parmar, V. S. (2005). Pure Appl. Chem. 77, 245-250.]). The crystal structure of the related compound 7,8-dihy­droxy-4-methyl­coumarin (Kurosaki et al., 2003[Kurosaki, H., Sharma, R. K., Otsuka, M. & Goto, M. (2003). Anal. Sci. 19, 647-648.]) has been reported. Pentynoyl probes have been used as chemical reporters to monitor protein acetyl­ation (Bateman et al., 2013[Bateman, L. A., Zaro, B. W., Miller, S. M. & Pratt, M. R. (2013). J. Am. Chem. Soc. 135, 14568-14573.]; Yang et al., 2010[Yang, Y., Ascano, J. M. & Hang, H. C. (2010). J. Am. Chem. Soc. 132, 3640-3641.]). For background to bio-orthogonal reactions using alkyne–azide cyclo­addition, see Sletten & Bertozzi (2011[Sletten, E. M. & Bertozzi, C. R. (2011). Acc. Chem. Res. 44, 666-676.]) and Yang & Hang (2011[Yang, Y. Y. & Hang, H. C. (2011). ChemBioChem, 12, 314-322.]).

[Scheme 1]

We have synthesized a new coumarin derivative, 7,8-dipentyno­yloxy-4-methyl coumarin, DPeMC (2) [systematic name: 4-methyl-2-oxo-2H chromene-7,8-diyl bis­(pent-4-ynoate)] as a chemical reporter of calreticulin's acyl­transferase capabilities (Singh et al., 2011[Singh, P., Ponnan, P., Priya, N., Tyagi, T. K., Gaspari, M., Krishnan, S., Cuda, G., Joshi, P., Gambhir, J. K., Sharma, S. K., Prasad, A. K., Saso, L., Rastogi, R. C., Parmar, V. S. & Raj, H. G. (2011). Protein Pept. Lett. 18, 507-517.]). As part of this work, the crystal structures of both coumarin derivatives are presented in this article.

2. Structural commentary

This paper reports the structures of two derivatives of coumarin (systematic name; 2H-chromen-2-one), C14H12O6 (1) and C20H16O6 (2), which are to be used as chemical reporters of calreticulin's acyl­transferase capabilities. These two compounds will be first discussed individually and then compared.

In the structure of (1) (Fig. 1[link]), the coumarin ring is almost planar (r.m.s. deviation of fitted atoms = 0.0063 Å) with O2 in the plane [deviation of 0.0048 (9) Å]. Both acetate substituents are significantly rotated out of this plane to minimize steric repulsions [dihedral angle of 66.19 (7)° to the coumarin ring for O3, O4, and C11, and 79.4 (3)° for O5, C13 O6A]. One acetate substituent is disordered over two equivalent conformations with occupancies of 0.755 (17) and 0.245 (17). The metrical parameters of both the coumarin ring and acetate substituents are in the normal ranges.

[Figure 1]
Figure 1
Diagram of the structure and numbering scheme for (1), showing the major occupancy component only. Atomic displacement parameters are drawn at the 30% probability level.

In (2) (Fig. 2[link]), the C C group of one of the pent-4-ynoate substituents is disordered over two positions with occupancies of 0.55 (2) and 0.45 (2). The coumarin ring is almost planar (r.m.s. deviation of fitted atoms = 0.0305 Å) with O2 significantly out of this plane [0.144 (2) Å] but O3 in the plane [0.063 (2) Å]. One of the pent-4-ynoate substituents is in an extended conformation (O5 to C21) while the other is in a bent conformation about C13. This can be seen from a consideration of the O3—C12—C13—C14 torsion angle of −46.3 (2)° compared to the equivalent torsion angle O5—C17—C18—C19 of 176.16 (12)°. The planar parts of both pent-4-ynoate substituents deviate from the coumarin plane but by different amounts [40.90 (15)° for O3, O4 and C12 compared to 74.07 (10)° for O5, O6 and C17]. The metrical parameters of both the coumarin ring and pent-4-ynoate substituents are in the normal ranges including the C C triple bonds [C15A C16A = 1.186 (9), C15B C16B = 1.169 (11) and C20 C21 = 1.177 (3) Å].

[Figure 2]
Figure 2
Diagram of the structure and numbering scheme for (2), showing the major occupancy component only. Atomic displacement parameters are drawn at the 30% probability level.

3. Supra­molecular features

The packing of (1) is dominated by ππ stacking involving the coumarin rings [centroid–centroid distance of 3.6640 (5) Å, slippage of 1.422 Å, symmetry code 1 − x, 1 − y, 1 − z]. This can be observed in Fig. 3[link]. In addition, there are weak C—H⋯O contacts (Table 1[link]) involving C13 and O6A(x, 1 + y, z) as well as C6 and O2(x − 1, 1 + y, z), C15A and O2 (1 − x, −y, 2 − z) which link the parallel stacks in the [101] direction.

Table 1
Hydrogen-bond geometry (Å, °) for (1)[link]

D—H⋯A D—H H⋯A DA D—H⋯A
C6—H6A⋯O2i 0.95 2.65 3.3465 (17) 130
C13—H13A⋯O6Aii 0.98 2.48 3.451 (5) 173
C15A—H15B⋯O2iii 0.98 2.52 3.401 (8) 150
Symmetry codes: (i) x-1, y+1, z; (ii) x, y+1, z; (iii) -x+1, -y, -z+2.
[Figure 3]
Figure 3
Packing diagram for (1), viewed along the c axis, showing the parallel coumarin rings. C—H⋯O secondary inter­actions are drawn with dashed lines.

In contrast to (1), for (2) the packing (Fig. 4[link]) is dominated by R22(24) hydrogen bonds (Table 2[link]) involving the acidic sp H atom and O2 which link the mol­ecules into centrosymmetric dimers. The bent conformation of one of the pent-4-ynoate substituents prevents the coumarin rings from engaging in ππ stacking in contrast to (1).

Table 2
Hydrogen-bond geometry (Å, °) for (2)[link]

D—H⋯A D—H H⋯A DA D—H⋯A
C13—H13B⋯O4i 0.99 2.43 3.244 (2) 139
C18—H18A⋯O6i 0.99 2.51 3.482 (2) 167
Symmetry code: (i) x-1, y, z.
[Figure 4]
Figure 4
Packing diagram for (2), viewed along the a axis. R22(24) hydrogen bonds involving the acidic sp H and O2 atoms link the mol­ecules into centrosymmetric dimers. C—H⋯O secondary inter­actions are drawn with dashed lines.

4. Database survey

Our group has reported a number of related structures (Jasinski & Paight, 1994[Jasinski, J. P. & Paight, E. S. (1994). Acta Cryst. C50, 1928-1930.], 1995[Jasinski, J. P. & Paight, E. S. (1995). Acta Cryst. C51, 531-533.]; Jasinski & Woudenberg, 1994[Jasinski, J. P. & Woudenberg, R. C. (1994). Acta Cryst. C50, 1952-1953.], 1995[Jasinski, J. P. & Woudenberg, R. C. (1995). Acta Cryst. C51, 107-109.]; Jasinski & Li, 2002[Jasinski, J. P. & Li, Y. (2002). Acta Cryst. E58, o1312-o1314.]; Jasinski et al., 1998[Jasinski, J. P., Jasinski, J. M. & Li, Y. (1998). Acta Cryst. C54, 410-412.], 2003[Jasinski, J. P., Jasinski, J. M., Li, Y. & Crosby, D. J. (2003). Acta Cryst. E59, o153-o154.]; Butcher et al., 2007[Butcher, R. J., Jasinski, J. P., Yathirajan, H. S., Narayana, B. & Samshad (2007). Acta Cryst. E63, o3412-o3413.]).

5. Synthesis and crystallization

7,8-Diacet­oxy-4-methyl­coumarin (1). 4-Methyl-2-oxo-2H-chromene-7,8-diyl di­acetate (DAMC) was synthesized using a previously reported procedure (Jalal et al., 2012[Jalal, S., Chand, K., Kathuria, A., Singh, P., Priya, N., Gupta, B., Raj, H. G. & Sharma, S. K. (2012). Bioorg. Chem. 40, 131-136.]).

7,8-Dipentyno­yloxy-4-methyl­coumarin (2). 0.5 mmol 7,8-dihy­droxy-4-methyl coumarin, DHMC [systematic name: 7,8-dihy­droxy-4-methyl-2H-chromen-2-one], 2.5 equivalents pentynoic anhydride (Malkoch et al., 2005[Malkoch, M., Schleicher, K., Drockenmuller, E., Hawker, C. J., Russell, T. P., Wu, P. & Fokin, V. V. (2005). Macromolecules, 38, 3663-3678.]) and catalytic 4-di­methyl­amino­pyridine (DMAP) was stirred for 24 h at room temperature in anhydrous THF (2 mL). Ice-cold water (25 mL) was added to the reaction flask, and the filtered crude product was washed with hexa­nes followed by recrystallization from ethanol to obtain small brown crystals of 4-methyl-2-oxo-2H chromene-7,8-diyl bis­(pent-4-ynoate).

Spectroscopic analysis: 1H NMR (400 MHz, CDCl3): δ 7.51–7.49 (1H, d), δ 7.20–7.17 (1H, d), δ 6.29 (1H, s), δ 3.01–3.08 (2H, m, HC C), δ 2.89–2.84 (2H, t, C C—CH2), δ 2.61–2.70 (4H, m, OOC—CH2), δ 2.44 (3H, s, CH3), δ 2.09–2.11 (2H, C C-CH2).

6. Refinement

Crystal data, data collection and structure refinement details are summarized in Table 3[link]. For (1), the H atoms were positioned geometrically and refined as riding: C—H = 0.95–0.98 Å with Uiso(H) = 1.5Ueq(C) for methyl H atoms and = 1.2Ueq(C) for other H atoms. One acetate substituent is disordered over two equivalent conformations with occupancies of 0.755 (17) and 0.245 (17).

Table 3
Experimental details

  (1) (2)
Crystal data
Chemical formula C14H12O6 C20H16O6
Mr 276.24 352.33
Crystal system, space group Triclinic, P[\overline{1}] Monoclinic, P21/n
Temperature (K) 173 200
a, b, c (Å) 7.3722 (10), 8.7235 (7), 11.7032 (15) 5.2785 (3), 16.3785 (8), 20.0502 (11)
α, β, γ (°) 69.263 (10), 87.519 (11), 69.113 (10) 90, 95.992 (2), 90
V3) 654.66 (14) 1723.95 (16)
Z 2 4
Radiation type Mo Kα Mo Kα
μ (mm−1) 0.11 0.10
Crystal size (mm) 0.33 × 0.26 × 0.11 0.55 × 0.14 × 0.11
 
Data collection
Diffractometer Agilent Xcalibur Eos Gemini Bruker Quest
Absorption correction Multi-scan (CrysAlis PRO; Agilent, 2014[Agilent (2014). CrysAlis PRO. Agilent Technologies, Yarnton, England.]) Multi-scan (SADABS; Sheldrick, 1996[Sheldrick, G. M. (1996). SADABS. University of Göttingen, Germany.])
Tmin, Tmax 0.883, 1.000 0.658, 0.746
No. of measured, independent and observed [I > 2σ(I)] reflections 7360, 4296, 3087 24358, 5276, 3859
Rint 0.036 0.035
(sin θ/λ)max−1) 0.759 0.716
 
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.055, 0.156, 1.04 0.057, 0.142, 1.07
No. of reflections 4296 5276
No. of parameters 192 255
No. of restraints 13 13
H-atom treatment H-atom parameters constrained H-atom parameters constrained
Δρmax, Δρmin (e Å−3) 0.36, −0.24 0.37, −0.21
Computer programs: CrysAlis PRO (Agilent, 2014[Agilent (2014). CrysAlis PRO. Agilent Technologies, Yarnton, England.]), APEX2 (Bruker, 2005[Bruker (2005). APEX2. Bruker AXS Inc., Madison, Wisconsin, USA.]), SAINT (Bruker, 2002[Bruker (2002). SAINT. Bruker AXS Inc., Madison, Wisconsin, USA.]), SHELXT (Sheldrick, 2015a[Sheldrick, G. M. (2015a). Acta Cryst. A71, 3-8.]), SHELXL2014 (Sheldrick, 2015b[Sheldrick, G. M. (2015b). Acta Cryst. C71, 3-8.]) and SHELXTL (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]).

In the refinement for (2), the H atoms were positioned geometrically and refined as riding: C—H = 0.95–0.99 Å with Uiso(H) = 1.5Ueq(C) for methyl H atoms and = 1.2Ueq(C) for other H atoms. The C C group of one of the pent-4-ynoate substituents is disordered over two positions with occupancies of 0.55 (2) and 0.45 (2).

Supporting information


Chemical context top

Coumarins and their derivatives have wide applications in a number of diverse areas. They are used in the pharmaceutical industry as precursor reagents in the synthesis of a number of synthetic anti­coagulant pharmaceuticals (Bairagi et al., 2012), the most notable being warfarin (Holbrook et al., 2005). Modified coumarins are a type of vitamin K antagonist (Marongiu & Barcellona, 2015).

In another important application, coumarin dyes are extensively used as gain media in blue–green tunable organic dye lasers (Schäfer, 1990; Duarte & Hillman, 1990; Duarte, 2003). Coumarin tetra­methyl laser dyes offer wide tunability and high laser gain (Chen et al., 1988; Duarte et al., 2006), and they are also used as the active medium in coherent OLED emitters (Duarte et al., 2005).

4-Methyl coumarin derivatives have previously been used as acetyl-group donors for post-translational modification of proteins via an acetyl–CoA independent mechanism (Raj, Singh et al., 2005; Raj, Kumari et al., 2006). Calreticulin-mediated acetyl­ation of gluta­thione-S-transferase (GST) using substrate 7,8-diacety­oxy-4-methyl coumarin, DAMC (1) (systematic name: 4-methyl-2-oxo-2H-chromene-7,8-diyl di­acetate has been shown to inhibit GST activity in a spectroscopic assay (Raj, Singh et al., 2005). Pentynoyl probes have been used as chemical reporters to monitor protein acetyl­ation (Bateman et al., 2013; Yang et al., 2010). For background to bio-orthogonal reactions using alkyne–azide cyclo­addition, see Sletten & Bertozzi (2011) and Yang & Hang 2011).

We have synthesized a new coumarin derivative, 7,8-dipentynoyl­oxy-4-methyl coumarin, DPeMC (2) [systematic name: 4-methyl-2-oxo-2H chromene-7,8-diyl bis­(pent-4-ynoate)] as a chemical reporter of calreticulin's acyl­transferase capabilities. As part of this work and as a continuation of our previous structural studies of coumarin derivatives (Jasinski & Paight, 1994, 1995; Jasinski & Woudenberg, 1994, 1995; Jasinski & Li, 2002; Jasinski et al., 1998, 2003; Butcher et al., 2007), the crystal structures of both coumarin derivatives are presented in this article.

Structural commentary top

This paper reports the structures of two derivatives of coumarin (systematic name; 2H-chromen-2-one), C14H12O6 (1) and C20H16O6 (2), which are to be used as chemical reporters of calreticulin's acyl­transferase capabilities. These two compounds will be first discussed individually and then compared.

In the structure of (1) (Fig. 1), the coumarin ring is planar (r.m.s. deviation of fitted atoms = 0.0063 Å) with O2 in the plane [deviation of 0.0048 (9) Å]. Both acetate substituents are significantly rotated out of this plane to minimize steric repulsions [dihedral angle of 66.19 (7)° to the coumarin ring for O3, O4, and C11, and 79.4 (3)° for O5, C13 O6A]. One acetate substituent is disordered over two equivalent conformations with occupancies of 0.755 (17) and 0.245 (17). The metrical parameters of both the coumarin ring and acetate substituents are in the normal ranges.

By contrast with (1), in the structure of (2) (Fig. 2) there are two pent-4-ynoate substituents in place of the acetate substituents. The C C group of one of the pent-4-ynoate substituents is disordered over two positions with occupancies of 0.55 (2) and 0.45 (2). The coumarin ring is planar (r.m.s. deviation of fitted atoms = 0.0305 Å) with O2 significantly out of this plane [0.144 (2) Å] but O3 in the plane [0.063 (2) Å]. One of the pent-4-ynoate substituents is in an extended conformation (O5 to C21) while the other is in a bent conformation about C13. This can be seen clearly from a consideration of the O3—C12—C13—C14 torsion angle of -46.3 (2)° compared to the equivalent torsion angle O5—C17—C18—C19 of 176.16 (12)°. The planar parts of both pent-4-ynoate substituents deviate from the coumarin plane but by different amounts [40.90 (15)° for O3, O4 and C12 compared to 74.07 (10)° for O5, O6 and C17]. The metrical parameters of both the coumarin ring and pent-4-ynoate substituents are in the normal ranges including the CC triple bonds [C15AC16A = 1.186 (9), C15B C16B = 1.169 (11) and C20C21 = 1.177 (3) Å].

Supra­molecular features top

The packing of (1) is dominated by ππ stacking involving the coumarin rings [centroid–centroid distance of 3.6640 (5) Å, slippage of 1.422 Å, symmetry code 1 - x, 1 - y, 1 - z]. This can be observed in Fig. 3. In addition, there are weak C—H···O contacts involving C13 and O6A(x, 1 + y, z) as well as C6 and O2(x - 1, 1 + y, z), C15A and O2 (1 - x, -y, 2 - z) which link the parallel stacks in the [101] direction.

In contract to (1), for (2) the packing is dominated by R22(24) hydrogen bonds involving the acidic sp H atom and O2 which link the molecules into centrosymmetric dimers. The bent conformation of one of the pent-4-ynoate substituents prevents the coumarin rings from engaging in ππ stacking in contrast to (1).

Database survey top

The crystal structure of 7,8-di­hydroxy-4-methyl­coumarin (Kurosaki et al., (2003) and other related coumarin structures (Jasinski & Paight, 1994, 1995; Jasinski & Woudenberg, 1994, 1995; Jasinski & Li, 2002; Jasinski et al., 1998, 2003; Butcher et al., 2007) have been reported. For more background on calreticulin transacetyl­ase activity, see Singh et al., (2011).

Synthesis and crystallization top

7,8-Di­acet­oxy-4-methyl­coumarin (1). 4-Methyl-2-oxo-2H-chromene-7,8-diyl di­acetate (DAMC) was synthesized using a previously reported procedure (Jalal et al., 2012).

7,8-Dipentynoyl­oxy-4-methyl­coumarin (2). 0.5 mmol 7,8-di­hydroxy-4-methyl coumarin, DHMC [systematic name: 7,8-di­hydroxy-4-methyl-2H-chromen-2-one], 2.5 equivalents pentynoic anhydride (Malkoch et al., 2005) and catalytic 4-di­methyl­amino­pyridine (DMAP) was stirred for 24 h at room temperature in anhydrous THF (2 mL). Ice-cold water (25 mL) was added to the reaction flask, and the filtered crude product was washed with hexanes followed by recrystallization from ethanol to obtain small brown crystals of 4-methyl-2-oxo-2H chromene-7,8-diyl bis­(pent-4-ynoate).

Spectroscopic analysis: 1H NMR (400 MHz, CDCl3): δ 7.51–7.49 (1H, d), δ 7.20–7.17 (1H, d), δ 6.29 (1H, s), δ 3.01–3.08 (2H, m, HCC), δ 2.89–2.84 (2H, t, CC—CH2), δ 2.61–2.70 (4H, m, OOC—CH2), δ 2.44 (3H, s, CH3), δ 2.09–2.11 (2H, CC-CH2).

Refinement top

Crystal data, data collection and structure refinement details are summarized in Table 3. For (1), the H atoms were positioned geometrically and refined as riding: C—H = 0.95–0.98 Å with Uiso(H) = 1.5Ueq(C) for methyl H atoms and = 1.2Ueq(C) for other H atoms. One acetate substituent is disordered over two equivalent conformations with occupancies of 0.755 (17) and 0.245 (17).

In the refinement for (2), the H atoms were positioned geometrically and refined as riding: C—H = 0.95–0.99 Å with Uiso(H) = 1.5Ueq(C) for methyl H atoms and = 1.2Ueq(C) for other H atoms. The CC group of one of the pent-4-ynoate substituents is disordered over two positions with occupancies of 0.55 (2) and 0.45 (2).

Structure description top

Coumarins and their derivatives have wide applications in a number of diverse areas. They are used in the pharmaceutical industry as precursor reagents in the synthesis of a number of synthetic anti­coagulant pharmaceuticals (Bairagi et al., 2012), the most notable being warfarin (Holbrook et al., 2005). Modified coumarins are a type of vitamin K antagonist (Marongiu & Barcellona, 2015).

In another important application, coumarin dyes are extensively used as gain media in blue–green tunable organic dye lasers (Schäfer, 1990; Duarte & Hillman, 1990; Duarte, 2003). Coumarin tetra­methyl laser dyes offer wide tunability and high laser gain (Chen et al., 1988; Duarte et al., 2006), and they are also used as the active medium in coherent OLED emitters (Duarte et al., 2005).

4-Methyl coumarin derivatives have previously been used as acetyl-group donors for post-translational modification of proteins via an acetyl–CoA independent mechanism (Raj, Singh et al., 2005; Raj, Kumari et al., 2006). Calreticulin-mediated acetyl­ation of gluta­thione-S-transferase (GST) using substrate 7,8-diacety­oxy-4-methyl coumarin, DAMC (1) (systematic name: 4-methyl-2-oxo-2H-chromene-7,8-diyl di­acetate has been shown to inhibit GST activity in a spectroscopic assay (Raj, Singh et al., 2005). Pentynoyl probes have been used as chemical reporters to monitor protein acetyl­ation (Bateman et al., 2013; Yang et al., 2010). For background to bio-orthogonal reactions using alkyne–azide cyclo­addition, see Sletten & Bertozzi (2011) and Yang & Hang 2011).

We have synthesized a new coumarin derivative, 7,8-dipentynoyl­oxy-4-methyl coumarin, DPeMC (2) [systematic name: 4-methyl-2-oxo-2H chromene-7,8-diyl bis­(pent-4-ynoate)] as a chemical reporter of calreticulin's acyl­transferase capabilities. As part of this work and as a continuation of our previous structural studies of coumarin derivatives (Jasinski & Paight, 1994, 1995; Jasinski & Woudenberg, 1994, 1995; Jasinski & Li, 2002; Jasinski et al., 1998, 2003; Butcher et al., 2007), the crystal structures of both coumarin derivatives are presented in this article.

This paper reports the structures of two derivatives of coumarin (systematic name; 2H-chromen-2-one), C14H12O6 (1) and C20H16O6 (2), which are to be used as chemical reporters of calreticulin's acyl­transferase capabilities. These two compounds will be first discussed individually and then compared.

In the structure of (1) (Fig. 1), the coumarin ring is planar (r.m.s. deviation of fitted atoms = 0.0063 Å) with O2 in the plane [deviation of 0.0048 (9) Å]. Both acetate substituents are significantly rotated out of this plane to minimize steric repulsions [dihedral angle of 66.19 (7)° to the coumarin ring for O3, O4, and C11, and 79.4 (3)° for O5, C13 O6A]. One acetate substituent is disordered over two equivalent conformations with occupancies of 0.755 (17) and 0.245 (17). The metrical parameters of both the coumarin ring and acetate substituents are in the normal ranges.

By contrast with (1), in the structure of (2) (Fig. 2) there are two pent-4-ynoate substituents in place of the acetate substituents. The C C group of one of the pent-4-ynoate substituents is disordered over two positions with occupancies of 0.55 (2) and 0.45 (2). The coumarin ring is planar (r.m.s. deviation of fitted atoms = 0.0305 Å) with O2 significantly out of this plane [0.144 (2) Å] but O3 in the plane [0.063 (2) Å]. One of the pent-4-ynoate substituents is in an extended conformation (O5 to C21) while the other is in a bent conformation about C13. This can be seen clearly from a consideration of the O3—C12—C13—C14 torsion angle of -46.3 (2)° compared to the equivalent torsion angle O5—C17—C18—C19 of 176.16 (12)°. The planar parts of both pent-4-ynoate substituents deviate from the coumarin plane but by different amounts [40.90 (15)° for O3, O4 and C12 compared to 74.07 (10)° for O5, O6 and C17]. The metrical parameters of both the coumarin ring and pent-4-ynoate substituents are in the normal ranges including the CC triple bonds [C15AC16A = 1.186 (9), C15B C16B = 1.169 (11) and C20C21 = 1.177 (3) Å].

The packing of (1) is dominated by ππ stacking involving the coumarin rings [centroid–centroid distance of 3.6640 (5) Å, slippage of 1.422 Å, symmetry code 1 - x, 1 - y, 1 - z]. This can be observed in Fig. 3. In addition, there are weak C—H···O contacts involving C13 and O6A(x, 1 + y, z) as well as C6 and O2(x - 1, 1 + y, z), C15A and O2 (1 - x, -y, 2 - z) which link the parallel stacks in the [101] direction.

In contract to (1), for (2) the packing is dominated by R22(24) hydrogen bonds involving the acidic sp H atom and O2 which link the molecules into centrosymmetric dimers. The bent conformation of one of the pent-4-ynoate substituents prevents the coumarin rings from engaging in ππ stacking in contrast to (1).

The crystal structure of 7,8-di­hydroxy-4-methyl­coumarin (Kurosaki et al., (2003) and other related coumarin structures (Jasinski & Paight, 1994, 1995; Jasinski & Woudenberg, 1994, 1995; Jasinski & Li, 2002; Jasinski et al., 1998, 2003; Butcher et al., 2007) have been reported. For more background on calreticulin transacetyl­ase activity, see Singh et al., (2011).

Synthesis and crystallization top

7,8-Di­acet­oxy-4-methyl­coumarin (1). 4-Methyl-2-oxo-2H-chromene-7,8-diyl di­acetate (DAMC) was synthesized using a previously reported procedure (Jalal et al., 2012).

7,8-Dipentynoyl­oxy-4-methyl­coumarin (2). 0.5 mmol 7,8-di­hydroxy-4-methyl coumarin, DHMC [systematic name: 7,8-di­hydroxy-4-methyl-2H-chromen-2-one], 2.5 equivalents pentynoic anhydride (Malkoch et al., 2005) and catalytic 4-di­methyl­amino­pyridine (DMAP) was stirred for 24 h at room temperature in anhydrous THF (2 mL). Ice-cold water (25 mL) was added to the reaction flask, and the filtered crude product was washed with hexanes followed by recrystallization from ethanol to obtain small brown crystals of 4-methyl-2-oxo-2H chromene-7,8-diyl bis­(pent-4-ynoate).

Spectroscopic analysis: 1H NMR (400 MHz, CDCl3): δ 7.51–7.49 (1H, d), δ 7.20–7.17 (1H, d), δ 6.29 (1H, s), δ 3.01–3.08 (2H, m, HCC), δ 2.89–2.84 (2H, t, CC—CH2), δ 2.61–2.70 (4H, m, OOC—CH2), δ 2.44 (3H, s, CH3), δ 2.09–2.11 (2H, CC-CH2).

Refinement details top

Crystal data, data collection and structure refinement details are summarized in Table 3. For (1), the H atoms were positioned geometrically and refined as riding: C—H = 0.95–0.98 Å with Uiso(H) = 1.5Ueq(C) for methyl H atoms and = 1.2Ueq(C) for other H atoms. One acetate substituent is disordered over two equivalent conformations with occupancies of 0.755 (17) and 0.245 (17).

In the refinement for (2), the H atoms were positioned geometrically and refined as riding: C—H = 0.95–0.99 Å with Uiso(H) = 1.5Ueq(C) for methyl H atoms and = 1.2Ueq(C) for other H atoms. The CC group of one of the pent-4-ynoate substituents is disordered over two positions with occupancies of 0.55 (2) and 0.45 (2).

Computing details top

Data collection: CrysAlis PRO (Agilent, 2014) for (1); APEX2 (Bruker, 2005) for (2). Cell refinement: CrysAlis PRO (Agilent, 2014) for (1); APEX2 (Bruker, 2005) for (2). Data reduction: CrysAlis PRO (Agilent, 2014) for (1); SAINT (Bruker, 2002) for (2). For both compounds, program(s) used to solve structure: SHELXT (Sheldrick, 2015a); program(s) used to refine structure: SHELXL2014 (Sheldrick, 2015b); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Figures top
[Figure 1] Fig. 1. Diagram of the structure and numbering scheme for (1), showing the major occupancy component only. Atomic displacement parameters are drawn at the 30% probability level.
[Figure 2] Fig. 2. Diagram of the structure and numbering scheme for (2), showing the major occupancy component only. Atomic displacement parameters are drawn at the 30% probability level.
[Figure 3] Fig. 3. Packing diagram for (1), viewed along the c axis, showing the parallel coumarin rings. C—H···O secondary interactions are drawn with dashed bonds.
[Figure 4] Fig. 4. Packing diagram for (2), viewed along the a axis. R22(24) hydrogen bonds involving the acidic sp H and O2 atoms link the molecules into centrosymmetric dimers. C—H···O secondary interactions are drawn with dashed bonds.
(1) 4-Methyl-2-oxo-2H-chromene-7,8-diyl diacetate top
Crystal data top
C14H12O6Z = 2
Mr = 276.24F(000) = 288
Triclinic, P1Dx = 1.401 Mg m3
a = 7.3722 (10) ÅMo Kα radiation, λ = 0.71073 Å
b = 8.7235 (7) ÅCell parameters from 1905 reflections
c = 11.7032 (15) Åθ = 4.4–32.8°
α = 69.263 (10)°µ = 0.11 mm1
β = 87.519 (11)°T = 173 K
γ = 69.113 (10)°The symmetry employed for this shelxl refinement is uniquely defined by the following loop, which should always be used as a source of symmetry information in preference to the above space-group names. They are only intended as comments., colorless
V = 654.66 (14) Å30.33 × 0.26 × 0.11 mm
Data collection top
Agilent Xcalibur Eos Gemini
diffractometer
4296 independent reflections
Radiation source: Enhance (Mo) X-ray Source3087 reflections with I > 2σ(I)
Detector resolution: 16.0416 pixels mm-1Rint = 0.036
ω scansθmax = 32.7°, θmin = 3.2°
Absorption correction: multi-scan
(CrysAlis PRO; Agilent, 2014)
h = 118
Tmin = 0.883, Tmax = 1.000k = 1312
7360 measured reflectionsl = 1617
Refinement top
Refinement on F213 restraints
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.055H-atom parameters constrained
wR(F2) = 0.156 w = 1/[σ2(Fo2) + (0.0738P)2 + 0.0282P]
where P = (Fo2 + 2Fc2)/3
S = 1.04(Δ/σ)max < 0.001
4296 reflectionsΔρmax = 0.36 e Å3
192 parametersΔρmin = 0.24 e Å3
Crystal data top
C14H12O6γ = 69.113 (10)°
Mr = 276.24V = 654.66 (14) Å3
Triclinic, P1Z = 2
a = 7.3722 (10) ÅMo Kα radiation
b = 8.7235 (7) ŵ = 0.11 mm1
c = 11.7032 (15) ÅT = 173 K
α = 69.263 (10)°0.33 × 0.26 × 0.11 mm
β = 87.519 (11)°
Data collection top
Agilent Xcalibur Eos Gemini
diffractometer
4296 independent reflections
Absorption correction: multi-scan
(CrysAlis PRO; Agilent, 2014)
3087 reflections with I > 2σ(I)
Tmin = 0.883, Tmax = 1.000Rint = 0.036
7360 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.05513 restraints
wR(F2) = 0.156H-atom parameters constrained
S = 1.04Δρmax = 0.36 e Å3
4296 reflectionsΔρmin = 0.24 e Å3
192 parameters
Special details top

Experimental. Absorption correction: CrysAlisPro (Agilent Technologies, 2014) Empirical absorption correction using spherical harmonics, implemented in SCALE3 ABSPACK scaling algorithm.

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/UeqOcc. (<1)
O10.48459 (13)0.24436 (11)0.69118 (8)0.0225 (2)
O20.67011 (16)0.00141 (12)0.66239 (10)0.0336 (3)
O30.09094 (15)0.73883 (12)0.78120 (9)0.0264 (2)
O40.20400 (17)0.95648 (13)0.68569 (10)0.0332 (3)
O50.38600 (14)0.41942 (12)0.84842 (8)0.0238 (2)
C20.54690 (19)0.14688 (16)0.61566 (13)0.0234 (3)
C30.4606 (2)0.22921 (16)0.49018 (12)0.0235 (3)
H3A0.50120.16460.43720.028*
C40.32496 (19)0.39359 (16)0.44454 (12)0.0203 (2)
C110.2429 (2)0.47678 (18)0.31289 (12)0.0267 (3)
H11A0.29250.39030.27290.040*
H11B0.28230.57750.27110.040*
H11C0.10030.51700.30850.040*
C100.26109 (18)0.49190 (15)0.52589 (11)0.0183 (2)
C50.11893 (18)0.66244 (15)0.49057 (12)0.0209 (3)
H5A0.05960.71970.40860.025*
C60.06342 (19)0.74874 (15)0.57236 (12)0.0225 (3)
H6A0.03390.86360.54730.027*
C70.15204 (19)0.66502 (15)0.69197 (12)0.0207 (2)
C80.29286 (18)0.49730 (15)0.72996 (11)0.0193 (2)
C90.34563 (17)0.41057 (14)0.64741 (12)0.0183 (2)
C120.1158 (2)0.89364 (16)0.76502 (13)0.0244 (3)
C130.0176 (3)0.9662 (2)0.85859 (16)0.0368 (4)
H13A0.06931.05280.86410.055*
H13B0.04210.87040.93860.055*
H13C0.12311.02320.83470.055*
C140.3169 (3)0.3042 (2)0.93265 (14)0.0376 (4)
O6A0.1945 (8)0.2587 (9)0.9046 (3)0.0509 (11)0.755 (17)
C15A0.4350 (12)0.2219 (9)1.0560 (7)0.0572 (13)0.755 (17)
H15A0.55020.12081.05680.086*0.755 (17)
H15B0.35500.18271.12070.086*0.755 (17)
H15C0.47640.30901.07060.086*0.755 (17)
O6B0.150 (2)0.3148 (19)0.9106 (11)0.0509 (11)0.245 (17)
C15B0.406 (4)0.265 (3)1.051 (2)0.0572 (13)0.245 (17)
H15D0.33430.35841.08180.086*0.245 (17)
H15E0.54150.25861.04350.086*0.245 (17)
H15F0.40390.15231.10730.086*0.245 (17)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
O10.0247 (5)0.0181 (4)0.0211 (5)0.0030 (3)0.0014 (4)0.0075 (3)
O20.0349 (6)0.0229 (5)0.0345 (6)0.0005 (4)0.0013 (5)0.0107 (4)
O30.0366 (5)0.0242 (4)0.0236 (5)0.0127 (4)0.0108 (4)0.0137 (4)
O40.0434 (6)0.0334 (5)0.0314 (6)0.0202 (5)0.0118 (5)0.0162 (4)
O50.0286 (5)0.0265 (4)0.0171 (4)0.0115 (4)0.0004 (4)0.0069 (3)
C20.0247 (6)0.0201 (5)0.0263 (7)0.0074 (5)0.0053 (5)0.0105 (5)
C30.0276 (6)0.0242 (6)0.0239 (7)0.0109 (5)0.0064 (5)0.0135 (5)
C40.0227 (6)0.0237 (5)0.0196 (6)0.0125 (5)0.0048 (5)0.0099 (5)
C110.0313 (7)0.0320 (7)0.0204 (7)0.0131 (6)0.0023 (5)0.0118 (5)
C100.0194 (6)0.0198 (5)0.0178 (6)0.0091 (4)0.0025 (4)0.0072 (4)
C50.0218 (6)0.0207 (5)0.0189 (6)0.0080 (4)0.0007 (5)0.0052 (4)
C60.0232 (6)0.0183 (5)0.0236 (7)0.0056 (4)0.0031 (5)0.0070 (5)
C70.0242 (6)0.0207 (5)0.0211 (6)0.0100 (5)0.0070 (5)0.0109 (5)
C80.0217 (6)0.0206 (5)0.0163 (6)0.0092 (4)0.0009 (4)0.0058 (4)
C90.0184 (5)0.0157 (5)0.0207 (6)0.0060 (4)0.0016 (4)0.0066 (4)
C120.0278 (6)0.0237 (6)0.0240 (7)0.0082 (5)0.0013 (5)0.0122 (5)
C130.0480 (9)0.0391 (8)0.0367 (9)0.0195 (7)0.0147 (7)0.0266 (7)
C140.0538 (10)0.0411 (8)0.0212 (7)0.0277 (7)0.0018 (7)0.0045 (6)
O6A0.076 (2)0.061 (2)0.0308 (8)0.053 (2)0.0009 (11)0.0047 (13)
C15A0.088 (3)0.055 (3)0.0236 (12)0.038 (3)0.0136 (16)0.006 (2)
O6B0.076 (2)0.061 (2)0.0308 (8)0.053 (2)0.0009 (11)0.0047 (13)
C15B0.088 (3)0.055 (3)0.0236 (12)0.038 (3)0.0136 (16)0.006 (2)
Geometric parameters (Å, º) top
O1—C91.3691 (14)C5—H5A0.9500
O1—C21.3906 (15)C6—C71.3910 (19)
O2—C21.2100 (16)C6—H6A0.9500
O3—C121.3731 (15)C7—C81.3829 (17)
O3—C71.3916 (15)C8—C91.3901 (17)
O4—C121.1945 (17)C12—C131.4898 (19)
O5—C141.3641 (17)C13—H13A0.9800
O5—C81.3921 (15)C13—H13B0.9800
C2—C31.4440 (19)C13—H13C0.9800
C3—C41.3502 (18)C14—O6A1.205 (4)
C3—H3A0.9500C14—O6B1.234 (14)
C4—C101.4544 (17)C14—C15B1.43 (2)
C4—C111.4973 (19)C14—C15A1.512 (7)
C11—H11A0.9800C15A—H15A0.9800
C11—H11B0.9800C15A—H15B0.9800
C11—H11C0.9800C15A—H15C0.9800
C10—C91.4005 (18)C15B—H15D0.9800
C10—C51.4045 (16)C15B—H15E0.9800
C5—C61.3810 (17)C15B—H15F0.9800
C9—O1—C2120.75 (10)C9—C8—O5120.50 (11)
C12—O3—C7117.51 (10)O1—C9—C8116.45 (11)
C14—O5—C8116.43 (11)O1—C9—C10122.58 (11)
O2—C2—O1116.03 (12)C8—C9—C10120.96 (11)
O2—C2—C3126.76 (13)O4—C12—O3122.90 (12)
O1—C2—C3117.20 (11)O4—C12—C13126.98 (13)
C4—C3—C2123.15 (12)O3—C12—C13110.12 (12)
C4—C3—H3A118.4C12—C13—H13A109.5
C2—C3—H3A118.4C12—C13—H13B109.5
C3—C4—C10118.48 (12)H13A—C13—H13B109.5
C3—C4—C11121.68 (12)C12—C13—H13C109.5
C10—C4—C11119.83 (11)H13A—C13—H13C109.5
C4—C11—H11A109.5H13B—C13—H13C109.5
C4—C11—H11B109.5O6A—C14—O5122.2 (2)
H11A—C11—H11B109.5O6B—C14—O5117.7 (6)
C4—C11—H11C109.5O6B—C14—C15B125.8 (15)
H11A—C11—H11C109.5O5—C14—C15B107.3 (11)
H11B—C11—H11C109.5O6A—C14—C15A125.4 (4)
C9—C10—C5118.01 (11)O5—C14—C15A111.6 (3)
C9—C10—C4117.84 (11)C14—C15A—H15A109.5
C5—C10—C4124.15 (12)C14—C15A—H15B109.5
C6—C5—C10121.47 (12)H15A—C15A—H15B109.5
C6—C5—H5A119.3C14—C15A—H15C109.5
C10—C5—H5A119.3H15A—C15A—H15C109.5
C5—C6—C7119.04 (11)H15B—C15A—H15C109.5
C5—C6—H6A120.5C14—C15B—H15D109.5
C7—C6—H6A120.5C14—C15B—H15E109.5
C8—C7—C6121.09 (11)H15D—C15B—H15E109.5
C8—C7—O3117.00 (11)C14—C15B—H15F109.5
C6—C7—O3121.65 (11)H15D—C15B—H15F109.5
C7—C8—C9119.41 (11)H15E—C15B—H15F109.5
C7—C8—O5120.05 (11)
C9—O1—C2—O2180.00 (11)O3—C7—C8—O58.72 (17)
C9—O1—C2—C30.67 (17)C14—O5—C8—C798.60 (15)
O2—C2—C3—C4179.19 (13)C14—O5—C8—C983.97 (15)
O1—C2—C3—C40.07 (19)C2—O1—C9—C8179.93 (11)
C2—C3—C4—C100.66 (19)C2—O1—C9—C100.79 (17)
C2—C3—C4—C11178.16 (12)C7—C8—C9—O1179.44 (10)
C3—C4—C10—C90.54 (17)O5—C8—C9—O13.11 (17)
C11—C4—C10—C9178.31 (11)C7—C8—C9—C101.28 (18)
C3—C4—C10—C5178.89 (11)O5—C8—C9—C10176.18 (10)
C11—C4—C10—C52.27 (19)C5—C10—C9—O1179.64 (10)
C9—C10—C5—C60.16 (18)C4—C10—C9—O10.18 (18)
C4—C10—C5—C6179.58 (11)C5—C10—C9—C81.12 (18)
C10—C5—C6—C70.63 (18)C4—C10—C9—C8179.42 (11)
C5—C6—C7—C80.48 (19)C7—O3—C12—O47.8 (2)
C5—C6—C7—O3174.49 (11)C7—O3—C12—C13171.97 (12)
C12—O3—C7—C8120.51 (13)C8—O5—C14—O6A6.8 (5)
C12—O3—C7—C665.25 (16)C8—O5—C14—O6B20.6 (8)
C6—C7—C8—C90.46 (18)C8—O5—C14—C15B169.5 (13)
O3—C7—C8—C9173.82 (11)C8—O5—C14—C15A177.4 (4)
C6—C7—C8—O5177.00 (11)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
C6—H6A···O2i0.952.653.3465 (17)130
C13—H13A···O6Aii0.982.483.451 (5)173
C15A—H15B···O2iii0.982.523.401 (8)150
Symmetry codes: (i) x1, y+1, z; (ii) x, y+1, z; (iii) x+1, y, z+2.
(2) 4-Methyl-2-oxo-2H-chromene-7,8-diyl bis(pent-4-ynoate) top
Crystal data top
C20H16O6F(000) = 736
Mr = 352.33Dx = 1.357 Mg m3
Monoclinic, P21/nMo Kα radiation, λ = 0.71073 Å
a = 5.2785 (3) ÅCell parameters from 9562 reflections
b = 16.3785 (8) Åθ = 2.5–30.4°
c = 20.0502 (11) ŵ = 0.10 mm1
β = 95.992 (2)°T = 200 K
V = 1723.95 (16) Å3Rod, colourless
Z = 40.55 × 0.14 × 0.11 mm
Data collection top
Bruker Quest
diffractometer
3859 reflections with I > 2σ(I)
ω scansRint = 0.035
Absorption correction: multi-scan
(SADABS; Sheldrick, 1996)
θmax = 30.6°, θmin = 2.5°
Tmin = 0.658, Tmax = 0.746h = 76
24358 measured reflectionsk = 2323
5276 independent reflectionsl = 2828
Refinement top
Refinement on F213 restraints
Least-squares matrix: fullHydrogen site location: mixed
R[F2 > 2σ(F2)] = 0.057H-atom parameters constrained
wR(F2) = 0.142 w = 1/[σ2(Fo2) + (0.0483P)2 + 1.0298P]
where P = (Fo2 + 2Fc2)/3
S = 1.07(Δ/σ)max < 0.001
5276 reflectionsΔρmax = 0.37 e Å3
255 parametersΔρmin = 0.21 e Å3
Crystal data top
C20H16O6V = 1723.95 (16) Å3
Mr = 352.33Z = 4
Monoclinic, P21/nMo Kα radiation
a = 5.2785 (3) ŵ = 0.10 mm1
b = 16.3785 (8) ÅT = 200 K
c = 20.0502 (11) Å0.55 × 0.14 × 0.11 mm
β = 95.992 (2)°
Data collection top
Bruker Quest
diffractometer
5276 independent reflections
Absorption correction: multi-scan
(SADABS; Sheldrick, 1996)
3859 reflections with I > 2σ(I)
Tmin = 0.658, Tmax = 0.746Rint = 0.035
24358 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.05713 restraints
wR(F2) = 0.142H-atom parameters constrained
S = 1.07Δρmax = 0.37 e Å3
5276 reflectionsΔρmin = 0.21 e Å3
255 parameters
Special details top

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/UeqOcc. (<1)
O10.4888 (2)0.14589 (6)0.70580 (6)0.0315 (3)
O20.7381 (3)0.03765 (8)0.70909 (7)0.0482 (4)
O30.0447 (2)0.37392 (7)0.67567 (6)0.0326 (3)
O40.1091 (2)0.50086 (8)0.66067 (7)0.0416 (3)
O50.0579 (2)0.21864 (7)0.64977 (5)0.0278 (2)
O60.3186 (2)0.22167 (8)0.56756 (6)0.0384 (3)
C20.7046 (3)0.10414 (10)0.73219 (8)0.0329 (3)
C30.8638 (3)0.14369 (10)0.78577 (8)0.0327 (3)
H3A1.00780.11500.80630.039*
C40.8176 (3)0.21931 (10)0.80793 (7)0.0289 (3)
C50.5425 (3)0.34519 (9)0.79035 (8)0.0309 (3)
H5A0.64810.37350.82400.037*
C60.3343 (3)0.38464 (10)0.75779 (8)0.0317 (3)
H6A0.29710.43950.76860.038*
C70.1793 (3)0.34264 (9)0.70865 (7)0.0272 (3)
C80.2314 (3)0.26251 (9)0.69265 (7)0.0249 (3)
C90.4453 (3)0.22431 (9)0.72504 (7)0.0253 (3)
C100.6024 (3)0.26439 (9)0.77514 (7)0.0263 (3)
C110.9821 (4)0.25697 (12)0.86536 (9)0.0394 (4)
H11D1.12440.22030.87940.056 (6)*
H11E0.88080.26590.90300.066 (7)*
H11F1.04840.30940.85120.068 (7)*
C120.0603 (3)0.45274 (10)0.65301 (8)0.0300 (3)
C130.3222 (3)0.46849 (11)0.61876 (10)0.0394 (4)
H13A0.32070.52090.59420.047*
H13B0.44200.47440.65330.047*
C140.4205 (4)0.40154 (13)0.56970 (11)0.0449 (5)
H14A0.591 (5)0.4172 (15)0.5499 (13)0.067 (7)*
H14B0.433 (4)0.3504 (13)0.5928 (11)0.042 (5)*
C15A0.280 (2)0.3949 (8)0.5166 (7)0.0399 (16)0.55 (2)
C16A0.147 (3)0.3912 (8)0.4725 (6)0.059 (2)0.55 (2)
H16A0.04100.38820.43710.071*0.55 (2)
C15B0.228 (3)0.3822 (10)0.5170 (8)0.0399 (16)0.45 (2)
C16B0.084 (3)0.3704 (10)0.4775 (8)0.059 (2)0.45 (2)
H16B0.03370.36090.44550.071*0.45 (2)
C170.1254 (3)0.19905 (9)0.58756 (7)0.0258 (3)
C180.0746 (3)0.14582 (10)0.55133 (8)0.0300 (3)
H18A0.24200.17340.54980.036*
H18B0.08560.09390.57620.036*
C190.0149 (3)0.12754 (10)0.48024 (8)0.0341 (4)
H19A0.01200.17940.45490.041*
H19B0.15670.10280.48190.041*
C200.2013 (4)0.07199 (10)0.44457 (8)0.0360 (4)
C210.3513 (4)0.02838 (12)0.41527 (10)0.0468 (5)
H210.47240.00680.39160.077 (8)*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
O10.0352 (6)0.0212 (5)0.0355 (6)0.0018 (4)0.0082 (5)0.0036 (4)
O20.0545 (8)0.0302 (6)0.0553 (8)0.0084 (6)0.0157 (6)0.0085 (6)
O30.0307 (6)0.0262 (6)0.0396 (6)0.0003 (4)0.0019 (5)0.0005 (5)
O40.0330 (6)0.0369 (7)0.0538 (8)0.0062 (5)0.0014 (5)0.0089 (6)
O50.0264 (5)0.0289 (5)0.0273 (5)0.0056 (4)0.0008 (4)0.0043 (4)
O60.0324 (6)0.0449 (7)0.0383 (6)0.0130 (5)0.0061 (5)0.0084 (5)
C20.0373 (9)0.0238 (7)0.0358 (8)0.0007 (6)0.0042 (7)0.0024 (6)
C30.0333 (8)0.0288 (8)0.0341 (8)0.0035 (6)0.0057 (6)0.0062 (6)
C40.0309 (8)0.0293 (7)0.0253 (7)0.0089 (6)0.0025 (6)0.0049 (6)
C50.0413 (9)0.0268 (7)0.0233 (7)0.0087 (6)0.0024 (6)0.0037 (6)
C60.0427 (9)0.0246 (7)0.0272 (7)0.0031 (6)0.0009 (6)0.0033 (6)
C70.0307 (7)0.0258 (7)0.0250 (7)0.0014 (6)0.0024 (6)0.0006 (5)
C80.0276 (7)0.0239 (7)0.0227 (6)0.0071 (6)0.0001 (5)0.0018 (5)
C90.0312 (7)0.0192 (6)0.0249 (7)0.0052 (6)0.0001 (5)0.0002 (5)
C100.0315 (7)0.0239 (7)0.0224 (7)0.0072 (6)0.0018 (5)0.0015 (5)
C110.0410 (9)0.0414 (10)0.0324 (8)0.0080 (8)0.0120 (7)0.0010 (7)
C120.0300 (8)0.0283 (8)0.0323 (8)0.0030 (6)0.0063 (6)0.0008 (6)
C130.0309 (8)0.0318 (9)0.0544 (11)0.0021 (7)0.0004 (7)0.0005 (7)
C140.0344 (9)0.0408 (10)0.0570 (12)0.0078 (8)0.0078 (8)0.0006 (9)
C15A0.043 (4)0.034 (4)0.0394 (10)0.006 (3)0.008 (2)0.0004 (19)
C16A0.071 (5)0.057 (5)0.051 (2)0.017 (3)0.008 (3)0.008 (3)
C15B0.043 (4)0.034 (4)0.0394 (10)0.006 (3)0.008 (2)0.0004 (19)
C16B0.071 (5)0.057 (5)0.051 (2)0.017 (3)0.008 (3)0.008 (3)
C170.0260 (7)0.0229 (7)0.0274 (7)0.0005 (5)0.0014 (5)0.0015 (5)
C180.0280 (7)0.0308 (8)0.0305 (8)0.0053 (6)0.0002 (6)0.0060 (6)
C190.0399 (9)0.0331 (8)0.0282 (8)0.0055 (7)0.0009 (6)0.0013 (6)
C200.0480 (10)0.0307 (8)0.0275 (8)0.0009 (7)0.0041 (7)0.0001 (6)
C210.0602 (12)0.0379 (10)0.0390 (10)0.0072 (9)0.0103 (9)0.0037 (8)
Geometric parameters (Å, º) top
O1—C91.3675 (18)C11—H11E0.9800
O1—C21.3851 (19)C11—H11F0.9800
O2—C21.204 (2)C12—C131.501 (2)
O3—C121.3682 (19)C13—C141.527 (3)
O3—C71.3911 (19)C13—H13A0.9900
O4—C121.189 (2)C13—H13B0.9900
O5—C171.3705 (18)C14—C15A1.364 (13)
O5—C81.3889 (17)C14—C15B1.574 (15)
O6—C171.1931 (19)C14—H14A0.98 (3)
C2—C31.446 (2)C14—H14B0.96 (2)
C3—C41.347 (2)C15A—C16A1.186 (9)
C3—H3A0.9500C16A—H16A0.9500
C4—C101.453 (2)C15B—C16B1.169 (11)
C4—C111.501 (2)C16B—H16B0.9500
C5—C61.379 (2)C17—C181.497 (2)
C5—C101.402 (2)C18—C191.521 (2)
C5—H5A0.9500C18—H18A0.9900
C6—C71.394 (2)C18—H18B0.9900
C6—H6A0.9500C19—C201.470 (2)
C7—C81.385 (2)C19—H19A0.9900
C8—C91.391 (2)C19—H19B0.9900
C9—C101.3977 (19)C20—C211.177 (3)
C11—H11D0.9800C21—H210.9500
C9—O1—C2120.77 (12)O3—C12—C13109.55 (14)
C12—O3—C7121.60 (12)C12—C13—C14113.95 (15)
C17—O5—C8117.86 (11)C12—C13—H13A108.8
O2—C2—O1116.59 (14)C14—C13—H13A108.8
O2—C2—C3126.42 (16)C12—C13—H13B108.8
O1—C2—C3116.97 (14)C14—C13—H13B108.8
C4—C3—C2123.07 (15)H13A—C13—H13B107.7
C4—C3—H3A118.5C15A—C14—C13112.6 (6)
C2—C3—H3A118.5C13—C14—C15B112.2 (7)
C3—C4—C10118.56 (14)C15A—C14—H14A104.9 (16)
C3—C4—C11121.39 (15)C13—C14—H14A107.9 (15)
C10—C4—C11120.05 (14)C15B—C14—H14A114.3 (16)
C6—C5—C10121.75 (14)C15A—C14—H14B112.2 (14)
C6—C5—H5A119.1C13—C14—H14B110.5 (13)
C10—C5—H5A119.1C15B—C14—H14B103.3 (14)
C5—C6—C7118.88 (14)H14A—C14—H14B108.4 (19)
C5—C6—H6A120.6C16A—C15A—C14176.4 (14)
C7—C6—H6A120.6C15A—C16A—H16A180.0
C8—C7—O3114.71 (13)C16B—C15B—C14177.9 (16)
C8—C7—C6121.01 (14)C15B—C16B—H16B180.0
O3—C7—C6124.13 (14)O6—C17—O5123.07 (13)
C7—C8—O5119.98 (13)O6—C17—C18127.00 (14)
C7—C8—C9119.26 (13)O5—C17—C18109.93 (13)
O5—C8—C9120.45 (13)C17—C18—C19111.39 (13)
O1—C9—C8116.28 (12)C17—C18—H18A109.4
O1—C9—C10122.63 (14)C19—C18—H18A109.4
C8—C9—C10121.07 (13)C17—C18—H18B109.4
C9—C10—C5117.99 (14)C19—C18—H18B109.4
C9—C10—C4117.62 (14)H18A—C18—H18B108.0
C5—C10—C4124.39 (13)C20—C19—C18112.58 (14)
C4—C11—H11D109.5C20—C19—H19A109.1
C4—C11—H11E109.5C18—C19—H19A109.1
H11D—C11—H11E109.5C20—C19—H19B109.1
C4—C11—H11F109.5C18—C19—H19B109.1
H11D—C11—H11F109.5H19A—C19—H19B107.8
H11E—C11—H11F109.5C21—C20—C19179.00 (19)
O4—C12—O3124.34 (15)C20—C21—H21180.0
O4—C12—C13126.10 (15)
C9—O1—C2—O2174.76 (15)O5—C8—C9—C10171.09 (13)
C9—O1—C2—C36.7 (2)O1—C9—C10—C5179.15 (14)
O2—C2—C3—C4178.29 (18)C8—C9—C10—C52.0 (2)
O1—C2—C3—C43.3 (2)O1—C9—C10—C40.8 (2)
C2—C3—C4—C102.0 (2)C8—C9—C10—C4178.12 (13)
C2—C3—C4—C11177.73 (16)C6—C5—C10—C90.6 (2)
C10—C5—C6—C70.3 (2)C6—C5—C10—C4179.52 (15)
C12—O3—C7—C8141.36 (14)C3—C4—C10—C94.1 (2)
C12—O3—C7—C643.1 (2)C11—C4—C10—C9175.69 (14)
C5—C6—C7—C80.3 (2)C3—C4—C10—C5175.83 (15)
C5—C6—C7—O3175.49 (14)C11—C4—C10—C54.4 (2)
O3—C7—C8—O53.7 (2)C7—O3—C12—O41.9 (2)
C6—C7—C8—O5171.99 (14)C7—O3—C12—C13179.10 (14)
O3—C7—C8—C9177.27 (13)O4—C12—C13—C14134.73 (19)
C6—C7—C8—C91.6 (2)O3—C12—C13—C1446.3 (2)
C17—O5—C8—C7111.09 (16)C12—C13—C14—C15A64.6 (6)
C17—O5—C8—C975.36 (17)C12—C13—C14—C15B53.0 (7)
C2—O1—C9—C8176.26 (14)C8—O5—C17—O64.2 (2)
C2—O1—C9—C104.8 (2)C8—O5—C17—C18174.99 (12)
C7—C8—C9—O1178.55 (13)O6—C17—C18—C194.7 (2)
O5—C8—C9—O17.9 (2)O5—C17—C18—C19176.16 (13)
C7—C8—C9—C102.5 (2)C17—C18—C19—C20177.12 (14)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
C13—H13B···O4i0.992.433.244 (2)139
C18—H18A···O6i0.992.513.482 (2)167
Symmetry code: (i) x1, y, z.
Hydrogen-bond geometry (Å, º) for (1) top
D—H···AD—HH···AD···AD—H···A
C6—H6A···O2i0.952.653.3465 (17)130.2
C13—H13A···O6Aii0.982.483.451 (5)173.1
C15A—H15B···O2iii0.982.523.401 (8)149.8
Symmetry codes: (i) x1, y+1, z; (ii) x, y+1, z; (iii) x+1, y, z+2.
Hydrogen-bond geometry (Å, º) for (2) top
D—H···AD—HH···AD···AD—H···A
C13—H13B···O4i0.992.433.244 (2)139.3
C18—H18A···O6i0.992.513.482 (2)166.8
Symmetry code: (i) x1, y, z.

Experimental details

(1)(2)
Crystal data
Chemical formulaC14H12O6C20H16O6
Mr276.24352.33
Crystal system, space groupTriclinic, P1Monoclinic, P21/n
Temperature (K)173200
a, b, c (Å)7.3722 (10), 8.7235 (7), 11.7032 (15)5.2785 (3), 16.3785 (8), 20.0502 (11)
α, β, γ (°)69.263 (10), 87.519 (11), 69.113 (10)90, 95.992 (2), 90
V3)654.66 (14)1723.95 (16)
Z24
Radiation typeMo KαMo Kα
µ (mm1)0.110.10
Crystal size (mm)0.33 × 0.26 × 0.110.55 × 0.14 × 0.11
Data collection
DiffractometerAgilent Xcalibur Eos GeminiBruker Quest
Absorption correctionMulti-scan
(CrysAlis PRO; Agilent, 2014)
Multi-scan
(SADABS; Sheldrick, 1996)
Tmin, Tmax0.883, 1.0000.658, 0.746
No. of measured, independent and
observed [I > 2σ(I)] reflections
7360, 4296, 3087 24358, 5276, 3859
Rint0.0360.035
(sin θ/λ)max1)0.7590.716
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.055, 0.156, 1.04 0.057, 0.142, 1.07
No. of reflections42965276
No. of parameters192255
No. of restraints1313
H-atom treatmentH-atom parameters constrainedH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.36, 0.240.37, 0.21

Computer programs: CrysAlis PRO (Agilent, 2014), APEX2 (Bruker, 2005), SAINT (Bruker, 2002), SHELXT (Sheldrick, 2015a), SHELXL2014 (Sheldrick, 2015b), SHELXTL (Sheldrick, 2008).

 

Acknowledgements

The authors wish to acknowledge the assistance of Dr Matthias Zeller in the collection of diffraction data and NSF Grant DMR 1337296 for funds to purchase the X-ray diffractometer. JPJ acknowledges the NSF–MRI program (grant No. CHE-1039027) for funds to purchase the Gemini–E X-ray diffractometer. RJB is grateful for the NSF award 1205608, Partnership for Reduced Dimensional Materials, for partial funding of this research as well as the Howard University Nanoscience Facility access to liquid nitro­gen. LAM wishes to acknowledge that this material is based upon work supported by the National Science Foundation under Howard University ADVANCE Institutional Transformation (HU ADVANCE-IT) Grant No. 1208880.

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ISSN: 2056-9890
Volume 72| Part 5| May 2016| Pages 704-708
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