organic compounds
tert-Butyl N-[1-diazoacetyl-3-(methylsulfanyl)propyl]carbamate
aDepartment of Chemistry, Quaid-I-Azam University, Islamabad 45320, Pakistan, and bInstitut für Anorganische und Analytische Chemie, Technische Universität Braunschweig, Hagenring 30, 38106 Braunschweig, Germany
*Correspondence e-mail: javid_zaidi@qau.edu.pk
In the enantiomerically pure title compound, C11H19N3O3S, the chain C—N—C(O)—O—C—C (from the asymmetric carbon to a methyl of the tert-butyl group) displays an extended conformation. In the crystal, molecules are linked into chains parallel to the c axis by classical N—H⋯Odiazocarbonyl hydrogen bonding and an unusual intermolecular three-centre interaction involving the amino acid (aa) carbonyl Oaa and the diazocarbonyl grouping C(O)—CH—N≡N, with H⋯Oaa = 2.51 Å and N⋯Oaa = 2.8141 (14) Å.
Related literature
For the applications of α-diazocarbonyl compounds in organic and, especially, natural product synthesis, see: Padwa & Weingarten (1996). The ready availability, relative stability and facile decomposition of these compounds under various conditions make them useful intermediates, see: Doyle et al. (1998). α-Diazoketones undergo a variety of transformations, see: Ye & McKervey (1994). Asymmetric versions of diazocarbonyl reactions have been reported to produce enantiomerically pure compounds, see: Doyle & McKervey (1997). The Arndt-Eistert synthesis, which consists of conversion of activated to diazoketones by the action of diazomethane followed by Wolf rearrangement, has become widely used in recent years for the synthesis of β-peptides and β-amino acid derivatives from appropriately protected α-amino acids, see: Müller et al. (1998).
Experimental
Crystal data
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Data collection: CrysAlis Pro (Oxford Diffraction, 2009); cell CrysAlis Pro; data reduction: CrysAlis Pro; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: XP (Siemens, 1994); software used to prepare material for publication: SHELXL97.
Supporting information
10.1107/S1600536809030815/at2855sup1.cif
contains datablocks I, global. DOI:Structure factors: contains datablock I. DOI: 10.1107/S1600536809030815/at2855Isup2.hkl
10 mmol of BOC-protected methionine was dissolved in 50 ml of dry distilled THF under inert conditions. To maintain basic conditions 12 mmol (1.66 ml) of triethylamine was added. Then 10 mmol (0.95 ml) of ethyl chloroformate was added, and the mixture stirred for 15 min at 248 K. 13 mmol of diazomethane were then added at 268 K and the mixture was further stirred for 30 min. After this temperature was allowed to rise to room temperature over 3 h. The reaction was then quenched with 3–4 drops of glacial acetic acid. The solvent was evaporated under vacuum. The residue was dissolved in ethyl acetate, extracted with aq. solutions of NaHCO3 and NH4Cl and dried over anhydrous MgSO4. The crude product was purified by
(yield 85%; m.p.326-328 K).The NH hydrogen was refined freely. Methyl H atoms were identified in difference syntheses, idealized and refined as rigid groups with C—H 0.98 Å and H—C—H angles 109.5°, allowed to rotate but not tip. Other H atoms were placed in calculated positions and refined using a riding model with C—H 0.98 Å (methylene) or 0.99 Å (methine); hydrogen U values were fixed at 1.5 × U(eq) of the parent atom for methyl H and 1.2 × U(eq) of the parent atom for other C—H. Data are 100% complete to 2θ 145°. The S at C6 (and thus the P31 rather than its P32) was determined by the Flack (1983) parameter, which refined to 0.023 (10).
α-Diazocarbonyl compounds find widespread applications in organic and, especially, natural product synthesis (Padwa & Weingarten, 1996). The ready availability, relative stability and facile decomposition of these compounds under various conditions (e.g. thermal, photochemical; acid-, base- and transition-metal-catalysis) make them useful intermediates (Doyle et al. 1998). Furthermore, α-diazoketones undergo a variety of transformations such as cyclopropanation, aziridine formation, ylide formation, C–H or C–X insertion reactions and reactions (Ye & McKervey, 1994). These reactions are chemoselective, and promote the formation of new carbon-carbon and carbon-heteroatom bonds under mild conditions. Asymmetric versions of diazocarbonyl reactions have been reported to produce compounds (Doyle & McKervey, 1997). One such method is the Arndt-Eistert synthesis, which consists of conversion of activated to diazoketones by the action of diazomethane, followed by Wolf rearrangement. The method has become widely used in recent years for the synthesis of β-peptides and β-amino acid derivatives from appropriately protected α-amino acids (Müller et al. 1998). Here we present the structure of an α-diazocarbonyl compound based on methionine.
The structure of the title compound is shown in Fig. 1. Molecular dimensions may be regarded as normal. The two essentially planar groupings N1,O1,O2,C2,4,5,6 and N2,N3,O3,C6,7,8 (r.m.s. deviations 0.04, 0.02 Å) subtend an interplanar angle of 84.75 (3)°. The atom chain C2 to C6 displays an extended conformation (minimum absolute torsion angle 170°).
The main feature of the molecular packing is the classical H bond N1—H1···O3, which links the molecules via the 31 screw operator to form chains parallel to the z axis (Fig. 2). Within the chains, an unusual three-centre interaction is also observed, whereby the carbonyl oxygen O2 is involved in short contacts to H8 and N2 of the diazocarbonyl group of a neighbouring molecule. The former is far from linear (angle 110°) but this is not unusual for three-centre interactions. The latter may be interpreted as a dipole-dipole interaction [dimensions: N2···O2 2.8141 (14) Å, C8—N2···O2 73.5 (1)°]. The remaining "weak" C—H···O interactions (Table 1) link neighbouring chains; H3B···O3 is implicit between the chains of Fig. 2 but is omitted for clarity.
For the applications of α-diazocarbonyl compounds in organic and, especially, natural product synthesis, see: Padwa & Weingarten (1996). The ready availability, relative stability and facile decomposition of these compounds under various conditions make them useful intermediates, see: Doyle et al. (1998). α-Diazoketones undergo a variety of transformations, see: Ye & McKervey (1994). Asymmetric versions of diazocarbonyl reactions have been reported to produce compounds, see: Doyle & McKervey (1997). The Arndt-Eistert synthesis, which consists of conversion of activated to diazoketones by the action of diazomethane followed by Wolf rearrangement, has become widely used in recent years for the synthesis of β-peptides and β-amino acid derivatives from appropriately protected α-amino acids, see: Müller et al. (1998).
Data collection: CrysAlis PRO (Oxford Diffraction, 2009); cell
CrysAlis PRO (Oxford Diffraction, 2009); data reduction: CrysAlis PRO (Oxford Diffraction, 2009); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: XP (Siemens, 1994); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).C11H19N3O3S | Dx = 1.183 Mg m−3 |
Mr = 273.35 | Cu Kα radiation, λ = 1.54184 Å |
Trigonal, P31 | Cell parameters from 14422 reflections |
Hall symbol: P 31 | θ = 3.2–75.7° |
a = 9.7915 (3) Å | µ = 1.93 mm−1 |
c = 13.8581 (5) Å | T = 100 K |
V = 1150.62 (6) Å3 | Tablet, colourless |
Z = 3 | 0.20 × 0.20 × 0.15 mm |
F(000) = 438 |
Oxford Diffraction Xcalibur Nova A diffractometer | 3073 independent reflections |
Radiation source: Nova (Cu) X-ray Source | 3051 reflections with I > 2σ(I) |
Mirror monochromator | Rint = 0.032 |
Detector resolution: 10.3543 pixels mm-1 | θmax = 75.6°, θmin = 5.2° |
ω scans | h = −12→12 |
Absorption correction: multi-scan (CrysAlis PRO; Oxford Diffraction, 2009) | k = −12→12 |
Tmin = 0.717, Tmax = 1.000 | l = −17→15 |
16152 measured reflections |
Refinement on F2 | Secondary atom site location: difference Fourier map |
Least-squares matrix: full | Hydrogen site location: inferred from neighbouring sites |
R[F2 > 2σ(F2)] = 0.023 | H atoms treated by a mixture of independent and constrained refinement |
wR(F2) = 0.060 | w = 1/[σ2(Fo2) + (0.0342P)2 + 0.1663P] where P = (Fo2 + 2Fc2)/3 |
S = 1.05 | (Δ/σ)max < 0.001 |
3073 reflections | Δρmax = 0.15 e Å−3 |
171 parameters | Δρmin = −0.14 e Å−3 |
1 restraint | Absolute structure: Flack (1983), 1474 Freidel pairs |
Primary atom site location: structure-invariant direct methods | Absolute structure parameter: 0.023 (10) |
C11H19N3O3S | Z = 3 |
Mr = 273.35 | Cu Kα radiation |
Trigonal, P31 | µ = 1.93 mm−1 |
a = 9.7915 (3) Å | T = 100 K |
c = 13.8581 (5) Å | 0.20 × 0.20 × 0.15 mm |
V = 1150.62 (6) Å3 |
Oxford Diffraction Xcalibur Nova A diffractometer | 3073 independent reflections |
Absorption correction: multi-scan (CrysAlis PRO; Oxford Diffraction, 2009) | 3051 reflections with I > 2σ(I) |
Tmin = 0.717, Tmax = 1.000 | Rint = 0.032 |
16152 measured reflections |
R[F2 > 2σ(F2)] = 0.023 | H atoms treated by a mixture of independent and constrained refinement |
wR(F2) = 0.060 | Δρmax = 0.15 e Å−3 |
S = 1.05 | Δρmin = −0.14 e Å−3 |
3073 reflections | Absolute structure: Flack (1983), 1474 Freidel pairs |
171 parameters | Absolute structure parameter: 0.023 (10) |
1 restraint |
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. Short contact: 2.8141 (14) N2 - O2_$1; 73.5 (1) C8 - N2 - O2_$1; Operator $1 - x + y+1, -x + 1, z - 1/3 |
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. |
x | y | z | Uiso*/Ueq | ||
S | 0.08692 (4) | −0.10432 (4) | 0.14682 (2) | 0.03648 (9) | |
O1 | 0.57182 (11) | 0.62115 (10) | 0.24352 (6) | 0.02868 (19) | |
O2 | 0.57776 (11) | 0.51506 (10) | 0.38885 (6) | 0.02855 (19) | |
O3 | 0.66256 (11) | 0.16891 (11) | 0.38136 (6) | 0.02857 (19) | |
N1 | 0.49938 (13) | 0.36907 (12) | 0.25188 (8) | 0.0259 (2) | |
H01 | 0.4999 (17) | 0.3757 (17) | 0.1913 (12) | 0.021 (3)* | |
N2 | 0.88980 (14) | 0.31145 (15) | 0.24685 (9) | 0.0340 (3) | |
N3 | 1.00277 (17) | 0.3112 (2) | 0.25596 (10) | 0.0492 (4) | |
C1 | 0.76526 (17) | 0.85794 (16) | 0.33133 (11) | 0.0350 (3) | |
H1A | 0.7632 | 0.7991 | 0.3890 | 0.052* | |
H1B | 0.7907 | 0.9647 | 0.3499 | 0.052* | |
H1C | 0.8455 | 0.8640 | 0.2865 | 0.052* | |
C2 | 0.60734 (19) | 0.86229 (16) | 0.19163 (11) | 0.0369 (3) | |
H2A | 0.6887 | 0.8685 | 0.1477 | 0.055* | |
H2B | 0.6307 | 0.9690 | 0.2085 | 0.055* | |
H2C | 0.5042 | 0.8059 | 0.1600 | 0.055* | |
C3 | 0.47294 (18) | 0.75163 (17) | 0.35029 (12) | 0.0364 (3) | |
H3A | 0.3714 | 0.6914 | 0.3172 | 0.055* | |
H3B | 0.4883 | 0.8548 | 0.3693 | 0.055* | |
H3C | 0.4739 | 0.6940 | 0.4079 | 0.055* | |
C4 | 0.60502 (15) | 0.77449 (14) | 0.28283 (10) | 0.0278 (3) | |
C5 | 0.55262 (14) | 0.50412 (13) | 0.30286 (9) | 0.0244 (2) | |
C6 | 0.48307 (14) | 0.22893 (14) | 0.29774 (9) | 0.0240 (2) | |
H6 | 0.4329 | 0.2173 | 0.3624 | 0.029* | |
C7 | 0.64131 (14) | 0.23513 (13) | 0.31215 (9) | 0.0234 (2) | |
C8 | 0.75513 (15) | 0.31186 (15) | 0.23793 (10) | 0.0288 (3) | |
H8 | 0.7356 | 0.3609 | 0.1847 | 0.035* | |
C9 | 0.37572 (14) | 0.08310 (13) | 0.23693 (9) | 0.0257 (2) | |
H9A | 0.4220 | 0.0957 | 0.1718 | 0.031* | |
H9B | 0.3707 | −0.0110 | 0.2670 | 0.031* | |
C10 | 0.20871 (15) | 0.05652 (15) | 0.22743 (10) | 0.0300 (3) | |
H10A | 0.2144 | 0.1544 | 0.2032 | 0.036* | |
H10B | 0.1588 | 0.0339 | 0.2920 | 0.036* | |
C11 | 0.0623 (2) | −0.26955 (18) | 0.21754 (14) | 0.0502 (4) | |
H11A | 0.1660 | −0.2559 | 0.2331 | 0.075* | |
H11B | 0.0012 | −0.3671 | 0.1806 | 0.075* | |
H11C | 0.0062 | −0.2755 | 0.2774 | 0.075* |
U11 | U22 | U33 | U12 | U13 | U23 | |
S | 0.03136 (16) | 0.03576 (17) | 0.03360 (17) | 0.01025 (14) | −0.00604 (13) | −0.00369 (14) |
O1 | 0.0426 (5) | 0.0199 (4) | 0.0260 (4) | 0.0176 (4) | −0.0038 (4) | −0.0017 (3) |
O2 | 0.0390 (5) | 0.0245 (4) | 0.0246 (5) | 0.0177 (4) | −0.0050 (3) | −0.0027 (3) |
O3 | 0.0319 (4) | 0.0295 (4) | 0.0243 (4) | 0.0153 (4) | 0.0004 (3) | 0.0041 (3) |
N1 | 0.0384 (6) | 0.0196 (5) | 0.0208 (5) | 0.0154 (4) | −0.0023 (4) | −0.0016 (4) |
N2 | 0.0324 (6) | 0.0379 (6) | 0.0292 (6) | 0.0157 (5) | 0.0058 (4) | 0.0081 (4) |
N3 | 0.0392 (7) | 0.0717 (10) | 0.0426 (8) | 0.0320 (7) | 0.0095 (6) | 0.0198 (7) |
C1 | 0.0336 (7) | 0.0248 (6) | 0.0424 (8) | 0.0115 (5) | −0.0030 (6) | −0.0028 (5) |
C2 | 0.0521 (8) | 0.0249 (6) | 0.0381 (8) | 0.0224 (6) | −0.0028 (6) | 0.0013 (5) |
C3 | 0.0400 (8) | 0.0309 (7) | 0.0456 (8) | 0.0230 (6) | 0.0044 (6) | 0.0018 (6) |
C4 | 0.0334 (6) | 0.0184 (5) | 0.0335 (7) | 0.0145 (5) | −0.0017 (5) | −0.0019 (5) |
C5 | 0.0271 (6) | 0.0203 (5) | 0.0282 (6) | 0.0137 (5) | −0.0001 (4) | −0.0001 (4) |
C6 | 0.0293 (6) | 0.0198 (5) | 0.0239 (6) | 0.0131 (5) | 0.0010 (4) | 0.0005 (4) |
C7 | 0.0275 (6) | 0.0170 (5) | 0.0228 (6) | 0.0091 (4) | −0.0009 (4) | −0.0021 (4) |
C8 | 0.0289 (6) | 0.0277 (6) | 0.0289 (6) | 0.0135 (5) | 0.0024 (5) | 0.0051 (5) |
C9 | 0.0273 (6) | 0.0199 (5) | 0.0289 (6) | 0.0110 (5) | −0.0003 (5) | −0.0015 (4) |
C10 | 0.0274 (6) | 0.0261 (6) | 0.0356 (7) | 0.0126 (5) | −0.0017 (5) | −0.0014 (5) |
C11 | 0.0479 (9) | 0.0284 (7) | 0.0653 (11) | 0.0124 (7) | −0.0165 (8) | −0.0071 (7) |
S—C11 | 1.8015 (17) | C1—H1A | 0.9800 |
S—C10 | 1.8089 (13) | C1—H1B | 0.9800 |
O1—C5 | 1.3450 (14) | C1—H1C | 0.9800 |
O1—C4 | 1.4727 (14) | C2—H2A | 0.9800 |
O2—C5 | 1.2107 (16) | C2—H2B | 0.9800 |
O3—C7 | 1.2323 (15) | C2—H2C | 0.9800 |
N1—C5 | 1.3528 (15) | C3—H3A | 0.9800 |
N1—C6 | 1.4468 (15) | C3—H3B | 0.9800 |
N2—N3 | 1.1145 (18) | C3—H3C | 0.9800 |
N2—C8 | 1.3264 (18) | C6—H6 | 1.0000 |
C1—C4 | 1.5163 (19) | C8—H8 | 0.9500 |
C2—C4 | 1.5223 (19) | C9—H9A | 0.9900 |
C3—C4 | 1.5189 (19) | C9—H9B | 0.9900 |
C6—C7 | 1.5330 (17) | C10—H10A | 0.9900 |
C6—C9 | 1.5340 (16) | C10—H10B | 0.9900 |
C7—C8 | 1.4237 (17) | C11—H11A | 0.9800 |
C9—C10 | 1.5276 (17) | C11—H11B | 0.9800 |
N1—H01 | 0.842 (16) | C11—H11C | 0.9800 |
C11—S—C10 | 100.36 (7) | H2A—C2—H2B | 109.5 |
C5—O1—C4 | 120.53 (10) | C4—C2—H2C | 109.5 |
C5—N1—C6 | 120.23 (11) | H2A—C2—H2C | 109.5 |
N3—N2—C8 | 178.84 (15) | H2B—C2—H2C | 109.5 |
O1—C4—C1 | 110.78 (10) | C4—C3—H3A | 109.5 |
O1—C4—C3 | 109.87 (10) | C4—C3—H3B | 109.5 |
C1—C4—C3 | 112.46 (12) | H3A—C3—H3B | 109.5 |
O1—C4—C2 | 101.65 (10) | C4—C3—H3C | 109.5 |
C1—C4—C2 | 110.15 (11) | H3A—C3—H3C | 109.5 |
C3—C4—C2 | 111.43 (11) | H3B—C3—H3C | 109.5 |
O2—C5—O1 | 126.21 (10) | N1—C6—H6 | 108.5 |
O2—C5—N1 | 124.23 (11) | C7—C6—H6 | 108.5 |
O1—C5—N1 | 109.57 (11) | C9—C6—H6 | 108.5 |
N1—C6—C7 | 112.93 (10) | N2—C8—H8 | 121.7 |
N1—C6—C9 | 109.93 (10) | C7—C8—H8 | 121.7 |
C7—C6—C9 | 108.48 (9) | C10—C9—H9A | 109.1 |
O3—C7—C8 | 123.12 (12) | C6—C9—H9A | 109.1 |
O3—C7—C6 | 120.91 (11) | C10—C9—H9B | 109.1 |
C8—C7—C6 | 115.84 (11) | C6—C9—H9B | 109.1 |
N2—C8—C7 | 116.62 (12) | H9A—C9—H9B | 107.8 |
C10—C9—C6 | 112.51 (10) | C9—C10—H10A | 109.1 |
C9—C10—S | 112.65 (9) | S—C10—H10A | 109.1 |
C5—N1—H01 | 117.4 (10) | C9—C10—H10B | 109.1 |
C6—N1—H01 | 120.3 (10) | S—C10—H10B | 109.1 |
C4—C1—H1A | 109.5 | H10A—C10—H10B | 107.8 |
C4—C1—H1B | 109.5 | S—C11—H11A | 109.5 |
H1A—C1—H1B | 109.5 | S—C11—H11B | 109.5 |
C4—C1—H1C | 109.5 | H11A—C11—H11B | 109.5 |
H1A—C1—H1C | 109.5 | S—C11—H11C | 109.5 |
H1B—C1—H1C | 109.5 | H11A—C11—H11C | 109.5 |
C4—C2—H2A | 109.5 | H11B—C11—H11C | 109.5 |
C4—C2—H2B | 109.5 | ||
C5—O1—C4—C1 | 66.13 (15) | C9—C6—C7—O3 | −89.46 (13) |
C5—O1—C4—C3 | −58.74 (14) | N1—C6—C7—C8 | −35.64 (15) |
C5—O1—C4—C2 | −176.85 (11) | C9—C6—C7—C8 | 86.47 (12) |
C4—O1—C5—O2 | −9.28 (19) | O3—C7—C8—N2 | −0.93 (19) |
C4—O1—C5—N1 | 170.45 (10) | C6—C7—C8—N2 | −176.76 (11) |
C6—N1—C5—O2 | −5.96 (19) | N1—C6—C9—C10 | −62.16 (13) |
C6—N1—C5—O1 | 174.30 (10) | C7—C6—C9—C10 | 173.92 (10) |
C5—N1—C6—C7 | −76.13 (14) | C6—C9—C10—S | 174.67 (9) |
C5—N1—C6—C9 | 162.57 (10) | C11—S—C10—C9 | 69.91 (11) |
N1—C6—C7—O3 | 148.43 (11) |
D—H···A | D—H | H···A | D···A | D—H···A |
N1—H01···O3i | 0.842 (16) | 2.027 (16) | 2.8465 (14) | 164.1 (14) |
C8—H8···O2i | 0.95 | 2.51 | 2.9686 (16) | 110 |
C11—H11B···O2ii | 0.98 | 2.52 | 3.457 (2) | 160 |
C3—H3B···O3iii | 0.98 | 2.67 | 3.5693 (17) | 152 |
C1—H1C···Siv | 0.98 | 2.95 | 3.9281 (16) | 177 |
Symmetry codes: (i) −x+y+1, −x+1, z−1/3; (ii) −x+y, −x, z−1/3; (iii) x, y+1, z; (iv) x+1, y+1, z. |
Experimental details
Crystal data | |
Chemical formula | C11H19N3O3S |
Mr | 273.35 |
Crystal system, space group | Trigonal, P31 |
Temperature (K) | 100 |
a, c (Å) | 9.7915 (3), 13.8581 (5) |
V (Å3) | 1150.62 (6) |
Z | 3 |
Radiation type | Cu Kα |
µ (mm−1) | 1.93 |
Crystal size (mm) | 0.20 × 0.20 × 0.15 |
Data collection | |
Diffractometer | Oxford Diffraction Xcalibur Nova A |
Absorption correction | Multi-scan (CrysAlis PRO; Oxford Diffraction, 2009) |
Tmin, Tmax | 0.717, 1.000 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 16152, 3073, 3051 |
Rint | 0.032 |
(sin θ/λ)max (Å−1) | 0.628 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.023, 0.060, 1.05 |
No. of reflections | 3073 |
No. of parameters | 171 |
No. of restraints | 1 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.15, −0.14 |
Absolute structure | Flack (1983), 1474 Freidel pairs |
Absolute structure parameter | 0.023 (10) |
Computer programs: CrysAlis PRO (Oxford Diffraction, 2009), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), XP (Siemens, 1994).
D—H···A | D—H | H···A | D···A | D—H···A |
N1—H01···O3i | 0.842 (16) | 2.027 (16) | 2.8465 (14) | 164.1 (14) |
C8—H8···O2i | 0.95 | 2.51 | 2.9686 (16) | 110.0 |
C11—H11B···O2ii | 0.98 | 2.52 | 3.457 (2) | 159.6 |
C3—H3B···O3iii | 0.98 | 2.67 | 3.5693 (17) | 152.0 |
C1—H1C···Siv | 0.98 | 2.95 | 3.9281 (16) | 177.2 |
Symmetry codes: (i) −x+y+1, −x+1, z−1/3; (ii) −x+y, −x, z−1/3; (iii) x, y+1, z; (iv) x+1, y+1, z. |
Acknowledgements
The authors are grateful to the Department of Chemistry, Quaid-I-Azam University, Islamabad, Pakistan, and the Institute for Inorganic Chemistry, University of Frankfurt, Germany, for providing laboratory and analytical facilities.
References
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α-Diazocarbonyl compounds find widespread applications in organic and, especially, natural product synthesis (Padwa & Weingarten, 1996). The ready availability, relative stability and facile decomposition of these compounds under various conditions (e.g. thermal, photochemical; acid-, base- and transition-metal-catalysis) make them useful intermediates (Doyle et al. 1998). Furthermore, α-diazoketones undergo a variety of transformations such as cyclopropanation, aziridine formation, ylide formation, C–H or C–X insertion reactions and cyclization reactions (Ye & McKervey, 1994). These reactions are chemoselective, and promote the formation of new carbon-carbon and carbon-heteroatom bonds under mild conditions. Asymmetric versions of diazocarbonyl reactions have been reported to produce enantiomerically pure compounds (Doyle & McKervey, 1997). One such method is the Arndt-Eistert synthesis, which consists of conversion of activated carboxylic acids to diazoketones by the action of diazomethane, followed by Wolf rearrangement. The method has become widely used in recent years for the synthesis of β-peptides and β-amino acid derivatives from appropriately protected α-amino acids (Müller et al. 1998). Here we present the structure of an α-diazocarbonyl compound based on methionine.
The structure of the title compound is shown in Fig. 1. Molecular dimensions may be regarded as normal. The two essentially planar groupings N1,O1,O2,C2,4,5,6 and N2,N3,O3,C6,7,8 (r.m.s. deviations 0.04, 0.02 Å) subtend an interplanar angle of 84.75 (3)°. The atom chain C2 to C6 displays an extended conformation (minimum absolute torsion angle 170°).
The main feature of the molecular packing is the classical H bond N1—H1···O3, which links the molecules via the 31 screw operator to form chains parallel to the z axis (Fig. 2). Within the chains, an unusual three-centre interaction is also observed, whereby the carbonyl oxygen O2 is involved in short contacts to H8 and N2 of the diazocarbonyl group of a neighbouring molecule. The former is far from linear (angle 110°) but this is not unusual for three-centre interactions. The latter may be interpreted as a dipole-dipole interaction [dimensions: N2···O2 2.8141 (14) Å, C8—N2···O2 73.5 (1)°]. The remaining "weak" C—H···O interactions (Table 1) link neighbouring chains; H3B···O3 is implicit between the chains of Fig. 2 but is omitted for clarity.