5-Chloro-3-hydr­oxy-2,2-dimethyl-2,3-dihydroquinazolin-4(1H)-one: supra­molecular aggregation through a two-dimensional network of N—H⋯O and O—H⋯O inter­actions

Vembu, N.; Spencer, E.C.; Lee, J.; Kelly, J.G.; Nolan, K.B.; Devocelle, M.

doi:10.1107/S1600536806040852

organic compounds

CRYSTALLOGRAPHIC
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ISSN: 2056-9890

Volume 62| Part 11| November 2006| Pages o5003-o5005

https://doi.org/10.1107/S1600536806040852

5-Chloro-3-hydroxy-2,2-dimethyl-2,3-dihydroquinazolin-4(1H)-one: supramolecular aggregation through a two-dimensional network of N—H⋯O and O—H⋯O interactions

Nagarajan Vembu,^a ^* Elinor C. Spencer,^b Jean Lee,^c John G. Kelly,^d Kevin B. Nolan ^c and Marc Devocelle ^c

^aDepartment of Chemistry, Urumu Dhanalakshmi College, Tiruchirappalli 620 019, India, ^bDepartment of Chemistry, Durham University, Durham DH1 3LE, England, ^cCentre for Synthesis and Chemical Biology, Department of Pharmaceutical and Medicinal Chemistry, Royal College of Surgeons in Ireland, 123 St. Stephen's Green, Dublin 2, Ireland, and ^dSchool of Pharmacy, Royal College of Surgeons in Ireland, 123 St. Stephen's Green, Dublin 2, Ireland
^*Correspondence e-mail: vembu57@yahoo.com

(Received 2 October 2006; accepted 3 October 2006; online 13 October 2006)

In the crystal structure of the title compound, C₁₀H₁₁ClN₂O₂, the 1,3-diaza ring exists in the skew-boat conformation. Supramolecular aggregation is effected by the formation of an infinite two-dimensional network of O—H⋯O and N—H⋯O interactions.

Comment

Quinazolin-4(1H)-ones, commonly known as benzopyrimidinones, are an important class of heterocyclic compounds (Jain et al., 2000 ). Some of them occur either as quinazoline alkaloids (Mohrle & Gundlack, 1970 ; Baker & McEvoy, 1995 ) or as their precursors (Brown, 1984 ). In addition, numerous synthetic quinazoline derivatives are known which exhibit diverse antihistaminic (Graham, 1960 ), diuretic (Cohen et al., 1960 ), hypnotic (Chappel & von Seeman, 1963 ) and anti-inflammatory (Saravanan et al., 1998 ) properties. In particular, 2,3-dihydro-1H-quinazolin-4-one derivatives are established as biologically and pharmaceutically important compounds (Bonala et al., 1968 ; Levin et al., 1994 ; Okumura et al., 1968 ; Yoo et al., 2005 ). The present investigation is aimed at the study of the molecular and supramolecular architecture of the title compound, (I), and may serve as a forerunner to a study of the correlation of these features with its biological activity.

The molecular structure of (I) is shown in Fig. 1 and selected geometric parameters are given in Table 1. The 1,3-diaza ring exists in a skew-boat conformation, with puckering parameters (Cremer & Pople, 1975 ) Q_T = 0.396 Å, θ = 64.6° and φ = 295.08°. This is also evident from the torsion angles involving the 1,3-diaza ring (Table 1). The axial orientation of the C10 methyl group, the equatorial orientation of the C8 methyl group, the equatorial orientation of the O atom of the N—OH group, and the relative synclinal orientation of the carbonyl O atom and the O atom of the N—OH group are evident from the corresponding torsion angles (Table 1).

The crystal structure of (I) is stabilized by the interplay of O—H⋯O and N—H⋯O interactions (Table 2), and van der Waals interactions. The hydrogen-bond distances found in (I) agree with those reported in the literature (Desiraju & Steiner, 1999 ; Desiraju, 1989 ). The O2—H2O⋯O1 interaction generates a motif of graph set S(5) (Bernstein et al., 1995 ; Etter, 1990 ). Two such S(5) motifs from symmetry-related molecules combine to form a binary motif of graph set R₂²(4). Another R₂²(4) binary motif is formed by the N2—H2N⋯O2ⁱ and N2—H2N⋯O1ⁱⁱ interactions (symmetry codes in Table 2), which is repeated between symmetry-related molecules. These repetitive S(5) and R₂²(4) motifs combine to form a higher-order motif of graph set R₂²(10) (Fig. 2). These N—H⋯O and O—H⋯O interactions generate an infinite two-dimensional network along [001] (Fig. 3). There is also a significant intramolecular van der Waals interaction between atoms Cl1 and O1 of 2.938 (2) Å.

Figure 1
The molecular structure of the title compound, showing 50% probability displacement ellipsoids

Figure 2
A view inclined to the c axis, showing the binary hydrogen-bonded motifs as dashed lines. (Symmetry codes as given in Table 2

Figure 3
A view along [001], showing the two-dimensional network of N—H⋯O and O—H⋯O interactions, drawn as dotted lines.

Experimental

6-Chloroanthranilic hydroxamic acid was prepared according to reported methods (Devocelle et al., 2003 ; Lee et al., 2005 ). During our attempts to recrystallize the above product from acetone–ethanol (1:1), crystals of the title compound were produced after standing for 30 d. These may have been formed by a condensation reaction of 6-chloroanthranilic hydroxamic acid with acetone. Such a reaction mechanism has already been reported for the formation of 2,3-dihydro-1H-quinazolin-4-one derivatives (Yoo et al. 2005).

Crystal data

C₁₀H₁₁ClN₂O₂
M_r = 226.66
Orthorhombic, P b c a
a = 9.7070 (5) Å
b = 12.7121 (7) Å
c = 16.4203 (8) Å
V = 2026.21 (18) Å³
Z = 8
D_x = 1.486 Mg m⁻³
Mo Kα radiation
μ = 0.36 mm⁻¹
T = 120 (2) K
Block, colourless
0.14 × 0.12 × 0.10 mm

Data collection

Bruker SMART 6K CCD area-detector diffractometer
ω scans
Absorption correction: multi-scan (SADABS; Sheldrick, 1998 ) T_min = 0.926, T_max = 0.965
12430 measured reflections
1996 independent reflections
1507 reflections with I > 2σ(I)
R_int = 0.052
θ_max = 26.0°

Refinement

Refinement on F²
R[F² > 2σ(F²)] = 0.038
wR(F²) = 0.107
S = 1.05
1996 reflections
180 parameters
All H-atom parameters refined
w = 1/[σ²(F_o²) + (0.0571P)² + 0.6859P] where P = (F_o² + 2F_c²)/3
(Δ/σ)_max < 0.001
Δρ_max = 0.32 e Å⁻³
Δρ_min = −0.22 e Å⁻³

Table 1
Selected torsion angles (°)

N2—C5—C6—C7	−6.9 (3)
C1—C6—C7—N1	−176.11 (19)
O1—C7—N1—O2	−11.8 (3)
C6—C7—N1—O2	172.09 (16)
C6—C7—N1—C9	19.0 (3)
N2—C9—N1—C7	−43.6 (3)
C8—C9—N1—C7	−159.8 (2)
C10—C9—N1—C7	77.1 (3)
N2—C9—N1—O2	162.41 (16)
C6—C5—N2—C9	−24.0 (3)
N1—C9—N2—C5	44.8 (2)
C8—C9—N2—C5	162.40 (18)
C10—C9—N2—C5	−73.9 (2)

Table 2
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N2—H2N⋯O2ⁱ	0.83 (3)	2.52 (3)	3.174 (2)	136 (2)
N2—H2N⋯O1ⁱⁱ	0.83 (3)	2.41 (3)	3.200 (2)	158 (2)
O2—H2O⋯O1	0.85 (3)	2.08 (3)	2.595 (2)	119 (2)
O2—H2O⋯O1ⁱⁱⁱ	0.85 (3)	2.00 (3)	2.677 (2)	136 (2)
Symmetry codes: (i) $[x-{\script{1\over 2}}, -y+{\script{1\over 2}}, -z+1]$ ; (ii) $[-x+{\script{1\over 2}}, y+{\script{1\over 2}}, z]$ ; (iii) -x+1, -y, -z+1.

All H atoms were located in a difference map, and their positions and isotropic displacement parameters were refined.

Data collection: SMART (Bruker, 1998 ); cell refinement: SAINT (Bruker, 1998); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: MERCURY (Macrae et al., 2006 ); software used to prepare material for publication: SHELXL97.

Supporting information

Crystal structure: contains datablocks I, global. DOI: https://doi.org/10.1107/S1600536806040852/sj2138sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536806040852/sj2138Isup2.hkl

Computing details top

Data collection: SMART (Bruker, 1998); cell refinement: SAINT (Bruker, 1998); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: Mercury (Macrae et al., 2006); software used to prepare material for publication: SHELXL97.

5-Chloro-3-hydroxy-2,2-dimethylquinazolin-4(1H)-one top

Crystal data top

C₁₀H₁₁ClN₂O₂	F(000) = 944
M_r = 226.66	D_x = 1.486 Mg m⁻³
Orthorhombic, Pbca	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ac 2ab	Cell parameters from 2345 reflections
a = 9.7070 (5) Å	θ = 2.5–25.3°
b = 12.7121 (7) Å	µ = 0.36 mm⁻¹
c = 16.4203 (8) Å	T = 120 K
V = 2026.21 (18) Å³	Block, colourless
Z = 8	0.14 × 0.12 × 0.10 mm

Data collection top

Bruker SMART 6K CCD area-detector diffractometer	1996 independent reflections
Radiation source: fine-focus sealed tube	1507 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.052
Detector resolution: 0 pixels mm^-1	θ_max = 26.0°, θ_min = 2.5°
ω scans	h = −11→11
Absorption correction: multi-scan (SADABS; Sheldrick, 1998)	k = −15→15
T_min = 0.926, T_max = 0.965	l = −15→20
12430 measured reflections

Refinement top

Refinement on F²	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F² > 2σ(F²)] = 0.038	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.107	All H-atom parameters refined
S = 1.05	w = 1/[σ²(F_o²) + (0.0571P)² + 0.6859P] where P = (F_o² + 2F_c²)/3
1996 reflections	(Δ/σ)_max < 0.001
180 parameters	Δρ_max = 0.32 e Å⁻³
0 restraints	Δρ_min = −0.22 e Å⁻³

Special details top

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

Refinement. Refinement of F² against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F², conventional R-factors R are based on F, with F set to zero for negative F². The threshold expression of F² > σ(F²) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F² are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
C1	0.1625 (2)	0.01410 (16)	0.30349 (13)	0.0232 (5)
C2	0.0732 (2)	0.04246 (18)	0.24247 (14)	0.0272 (5)
H2	0.061 (2)	−0.0020 (19)	0.1994 (14)	0.030 (6)*
C3	0.0072 (2)	0.13934 (17)	0.24633 (14)	0.0265 (5)
H3	−0.054 (2)	0.1577 (18)	0.2025 (14)	0.028 (6)*
C4	0.0253 (2)	0.20484 (17)	0.31133 (13)	0.0259 (5)
H4	−0.022 (2)	0.2718 (19)	0.3145 (14)	0.032 (6)*
C5	0.11145 (19)	0.17453 (16)	0.37553 (12)	0.0231 (4)
C6	0.18594 (19)	0.07904 (15)	0.37162 (12)	0.0210 (4)
C7	0.2901 (2)	0.05918 (15)	0.43529 (12)	0.0219 (4)
C8	0.2240 (2)	0.28916 (18)	0.57100 (15)	0.0288 (5)
H8A	0.146 (2)	0.3452 (17)	0.5774 (14)	0.030 (6)*
H8B	0.244 (2)	0.2654 (18)	0.6266 (16)	0.030 (6)*
H8C	0.303 (3)	0.320 (2)	0.5486 (15)	0.039 (7)*
C9	0.1737 (2)	0.19813 (16)	0.51952 (12)	0.0245 (5)
C10	0.0626 (2)	0.13579 (19)	0.56367 (15)	0.0313 (5)
H10C	−0.015 (3)	0.183 (2)	0.5808 (16)	0.047 (7)*
H10B	0.102 (3)	0.101 (2)	0.6148 (18)	0.048 (8)*
H10A	0.022 (3)	0.081 (2)	0.5298 (17)	0.050 (8)*
H2O	0.426 (3)	0.057 (2)	0.5458 (17)	0.048 (8)*
H2N	0.102 (3)	0.301 (2)	0.4410 (16)	0.047 (8)*
Cl1	0.24305 (5)	−0.10747 (4)	0.29303 (3)	0.02900 (19)
N1	0.28885 (18)	0.12826 (14)	0.49761 (11)	0.0260 (4)
N2	0.12798 (19)	0.23850 (15)	0.44190 (11)	0.0275 (4)
O1	0.38023 (14)	−0.01006 (11)	0.43358 (9)	0.0277 (4)
O2	0.37357 (16)	0.10485 (13)	0.56416 (9)	0.0312 (4)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
C1	0.0207 (10)	0.0231 (10)	0.0258 (11)	−0.0006 (8)	0.0044 (8)	−0.0004 (8)
C2	0.0283 (12)	0.0323 (12)	0.0211 (11)	−0.0029 (9)	−0.0006 (9)	−0.0013 (9)
C3	0.0230 (11)	0.0338 (12)	0.0226 (12)	0.0012 (9)	−0.0041 (9)	0.0043 (9)
C4	0.0236 (10)	0.0284 (11)	0.0258 (12)	0.0029 (9)	0.0014 (9)	0.0022 (9)
C5	0.0206 (10)	0.0247 (10)	0.0240 (11)	−0.0012 (8)	0.0027 (8)	0.0012 (8)
C6	0.0167 (9)	0.0249 (10)	0.0215 (10)	−0.0011 (8)	0.0015 (8)	0.0024 (8)
C7	0.0216 (10)	0.0215 (10)	0.0227 (11)	−0.0017 (8)	0.0024 (8)	0.0021 (8)
C8	0.0296 (12)	0.0292 (12)	0.0275 (13)	0.0005 (9)	0.0007 (10)	−0.0055 (10)
C9	0.0251 (10)	0.0258 (11)	0.0227 (11)	0.0038 (9)	−0.0003 (9)	−0.0012 (8)
C10	0.0312 (12)	0.0351 (13)	0.0275 (13)	−0.0041 (10)	0.0032 (10)	−0.0007 (10)
Cl1	0.0342 (3)	0.0250 (3)	0.0277 (3)	0.0047 (2)	−0.0037 (2)	−0.0053 (2)
N1	0.0248 (9)	0.0313 (10)	0.0220 (9)	0.0056 (7)	−0.0056 (7)	−0.0033 (7)
N2	0.0351 (10)	0.0227 (10)	0.0246 (10)	0.0055 (8)	−0.0027 (8)	−0.0015 (8)
O1	0.0257 (8)	0.0292 (8)	0.0281 (8)	0.0068 (6)	−0.0046 (6)	−0.0028 (6)
O2	0.0302 (8)	0.0393 (9)	0.0243 (9)	0.0121 (7)	−0.0089 (7)	−0.0075 (7)

Geometric parameters (Å, º) top

C1—C2	1.373 (3)	C8—C9	1.514 (3)
C1—C6	1.409 (3)	C8—H8A	1.05 (2)
C1—Cl1	1.740 (2)	C8—H8B	0.98 (3)
C2—C3	1.390 (3)	C8—H8C	0.93 (3)
C2—H2	0.91 (2)	C9—N2	1.444 (3)
C3—C4	1.365 (3)	C9—N1	1.473 (3)
C3—H3	0.96 (2)	C9—C10	1.522 (3)
C4—C5	1.399 (3)	C10—H10C	1.00 (3)
C4—H4	0.97 (2)	C10—H10B	1.02 (3)
C5—N2	1.369 (3)	C10—H10A	0.98 (3)
C5—C6	1.414 (3)	N1—O2	1.400 (2)
C6—C7	1.476 (3)	N2—H2N	0.83 (3)
C7—O1	1.242 (2)	O2—H2O	0.85 (3)
C7—N1	1.349 (3)

C2—C1—C6	121.83 (19)	H8A—C8—H8B	105.0 (19)
C2—C1—Cl1	116.40 (16)	C9—C8—H8C	111.2 (16)
C6—C1—Cl1	121.76 (16)	H8A—C8—H8C	111 (2)
C1—C2—C3	119.4 (2)	H8B—C8—H8C	109 (2)
C1—C2—H2	119.0 (15)	N2—C9—N1	103.41 (16)
C3—C2—H2	121.6 (15)	N2—C9—C8	108.69 (17)
C4—C3—C2	121.1 (2)	N1—C9—C8	110.62 (17)
C4—C3—H3	121.1 (14)	N2—C9—C10	112.83 (18)
C2—C3—H3	117.8 (14)	N1—C9—C10	109.90 (17)
C3—C4—C5	119.9 (2)	C8—C9—C10	111.14 (18)
C3—C4—H4	121.0 (14)	C9—C10—H10C	110.6 (15)
C5—C4—H4	119.1 (14)	C9—C10—H10B	110.7 (16)
N2—C5—C4	120.40 (19)	H10C—C10—H10B	108 (2)
N2—C5—C6	119.08 (18)	C9—C10—H10A	112.7 (16)
C4—C5—C6	120.49 (19)	H10C—C10—H10A	107 (2)
C1—C6—C5	117.16 (18)	H10B—C10—H10A	108 (2)
C1—C6—C7	124.94 (18)	C7—N1—O2	116.67 (16)
C5—C6—C7	117.69 (18)	C7—N1—C9	125.78 (17)
O1—C7—N1	119.01 (18)	O2—N1—C9	112.57 (16)
O1—C7—C6	126.01 (19)	C5—N2—C9	121.84 (17)
N1—C7—C6	114.85 (17)	C5—N2—H2N	121.1 (19)
C9—C8—H8A	110.0 (13)	C9—N2—H2N	116.5 (19)
C9—C8—H8B	110.4 (14)	N1—O2—H2O	103.1 (19)

C6—C1—C2—C3	2.1 (3)	C5—C6—C7—N1	9.2 (3)
Cl1—C1—C2—C3	−178.94 (16)	O1—C7—N1—O2	−11.8 (3)
C1—C2—C3—C4	−2.7 (3)	C6—C7—N1—O2	172.09 (16)
C2—C3—C4—C5	−0.1 (3)	O1—C7—N1—C9	−164.85 (19)
C3—C4—C5—N2	−178.50 (19)	C6—C7—N1—C9	19.0 (3)
C3—C4—C5—C6	3.5 (3)	N2—C9—N1—C7	−43.6 (3)
C2—C1—C6—C5	1.1 (3)	C8—C9—N1—C7	−159.8 (2)
Cl1—C1—C6—C5	−177.76 (14)	C10—C9—N1—C7	77.1 (3)
C2—C1—C6—C7	−173.57 (19)	N2—C9—N1—O2	162.41 (16)
Cl1—C1—C6—C7	7.6 (3)	C8—C9—N1—O2	46.2 (2)
N2—C5—C6—C1	178.05 (18)	C10—C9—N1—O2	−76.9 (2)
C4—C5—C6—C1	−3.9 (3)	C4—C5—N2—C9	157.99 (19)
N2—C5—C6—C7	−6.9 (3)	C6—C5—N2—C9	−24.0 (3)
C4—C5—C6—C7	171.16 (18)	N1—C9—N2—C5	44.8 (2)
C1—C6—C7—O1	8.1 (3)	C8—C9—N2—C5	162.40 (18)
C5—C6—C7—O1	−166.55 (19)	C10—C9—N2—C5	−73.9 (2)
C1—C6—C7—N1	−176.11 (19)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N2—H2N···O2ⁱ	0.83 (3)	2.52 (3)	3.174 (2)	136 (2)
N2—H2N···O1ⁱⁱ	0.83 (3)	2.41 (3)	3.200 (2)	158 (2)
O2—H2O···O1	0.85 (3)	2.08 (3)	2.595 (2)	119 (2)
O2—H2O···O1ⁱⁱⁱ	0.85 (3)	2.00 (3)	2.677 (2)	136 (2)

Symmetry codes: (i) x−1/2, −y+1/2, −z+1; (ii) −x+1/2, y+1/2, z; (iii) −x+1, −y, −z+1.

Acknowledgements

NV and ECS thank Professor Judith A. K. Howard, Department of Chemistry, Durham University, UK, for discussions. JL, JGK, KBN and MD thank the Irish Government under its `Programme for Research in Third Level Institutions' and the Research Committee of the Royal College of Surgeons in Ireland for financial support.

References

Baker, B. R. & McEvoy, F. J. (1995). J. Org. Chem. 60, 136–142. Google Scholar
Bernstein, J., Davis, R. E., Shimoni, L. & Chang, N.-L. (1995). Angew. Chem. Int. Ed. Engl. 34, 1555–1573. CrossRef CAS Web of Science Google Scholar
Bonala, G., Da Re, P., Magistretti, M. J., Massarani, E. & Setnikar, I. (1968). J. Med. Chem. 11, 1136–1139. CrossRef PubMed Web of Science Google Scholar
Brown, D. J. (1984). Comprehensive Heterocyclic Chemistry, edited by A. R. Katritzky & C. W. Rees, Vol III, pp. 57–155. Oxford: Pergamon Press. Google Scholar
Bruker (1998). SMART-NT and SAINT-NT. Versions 5.0. Bruker AXS Inc., Madison, Wisconsin, USA. Google Scholar
Chappel, C. I. & von Seeman, C. (1963). Prog. Med. Chem. 3, 89–145. CrossRef Google Scholar
Cohen, E., Klarber, B. & Vaughan, J. R. (1960). J. Am. Chem. Soc. 82, 2731–2735. CrossRef CAS Web of Science Google Scholar
Cremer, D. & Pople, J. A. (1975). J. Am. Chem. Soc. 97, 1354–1358. CrossRef CAS Web of Science Google Scholar
Desiraju, G. R. (1989). Crystal Engineering: The Design of Organic Solids. Amsterdam: Elsevier. Google Scholar
Desiraju, G. R. & Steiner, T. (1999). The Weak Hydrogen Bond in Structural Chemistry and Biology. New York: Oxford University Press Inc. Google Scholar
Devocelle, M., Mc Loughlin, B. M., Sharkey, C. T., Fitzgerald, D. J. & Nolan, K. B. (2003). Org. Biomol. Chem. 1, 850–853. Web of Science CrossRef PubMed CAS Google Scholar
Etter, M. C. (1990). Acc. Chem. Res. 23, 120–126. CrossRef CAS Web of Science Google Scholar
Graham, J. D. P. (1960). Arch. Int. Pharmacodyn. Ther. 123, 419–420. PubMed CAS Web of Science Google Scholar
Jain, S. C., Bharadvaja, A., Kumar, R., Agarwal, D. & Errington, W. (2000). Acta Cryst. C56, 592–593. CSD CrossRef CAS IUCr Journals Google Scholar
Lee, J., Chubb, A. J., Moman, E., Mc Loughlin, B. M., Sharkey, C. T., Kelly, J. G., Nolan, K. B., Devocelle, M. & Fitzgerald, D. J. (2005). Org. Biomol. Chem. 3, 3678–3685. Web of Science CrossRef PubMed CAS Google Scholar
Levin, J. I., Chan, P. S., Bailey, T., Katocs, A. S. Jr & Venkatesan, A. M. (1994). Bioorg. Med. Chem. Lett. 4, 1141–1146. CrossRef CAS Web of Science Google Scholar
Macrae, C. F., Edgington, P. R., McCabe, P., Pidcock, E., Shields, G. P., Taylor, R., Towler, M. & van de Streek, J. (2006). J. Appl. Cryst. 39, 453–457. Web of Science CSD CrossRef CAS IUCr Journals Google Scholar
Mohrle, H. & Gundlack, P. (1970). Tetrahedron Lett. pp. 3249–3250. Google Scholar
Okumura, K., Oine, T., Yamada, Y., Hayashi, G. & Nakama, M. (1968). J. Med. Chem. 11, 348–352. CrossRef CAS PubMed Web of Science Google Scholar
Saravanan, J., Mohan, S. & Majunatha, K. S. (1998). Indian J. Heterocycl. Chem. 8, 55–58. CAS Google Scholar
Sheldrick, G. M. (1997). SHELXS97 and SHELXL97. University of Göttingen, Germany. Google Scholar
Sheldrick, G. M. (1998). SADABS. University of Göttingen, Germany. Google Scholar
Yoo, C. L., Fettinger, J. C. & Kurth, M. J. (2005). J. Org. Chem. 70, 6941–6943. Web of Science CSD CrossRef PubMed CAS Google Scholar

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