C. Mamat, M. Köckerling, C. Geers
2008
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Zeitschrift für Kristallographie - New Crystal Structures
Abstract
C12H12O3, monoclinic, P121/c1 (no. 14), a = 9.5426(4) Å, b = 5.6908(2) Å, c = 19.4581(8) Å, 3 = 93.416(3)°, V = 1054.8 Å, Z = 4, Rgt(F) = 0.049, wRref(F) = 0.162, T = 293 K. Source of material The title compound was found as a side product in the formation of the respective saturated derivative 3-oxo-5-phenyl-pentanoic acid methyl ester according to [1]. After purification via column chromatography a small amount of colorless needles was obtained from a mixture of both compounds after several weeks (m.p. 72 °C). Analytical data are in accordance with the previously published data [2]. Experimental details Hydrogen atoms were located from Fourier difference maps, and refined with isotropic displacement parameters based on the bonded atoms. Discussion 1,3-Dicarbonyl compounds are of substantial interest as dielectrophilic sources in the synthesis of various heterocyclic compounds [3,4]. The preparation of the title compound is possible in differentways.Methyl cinnamatewas convertedwithmethyl acetate in an ester condensation to yield the desired compound [5]. Furthermore it can be obtained as by-product in lipase-catalysed reactions of 3-hydroxy-3-arylpropionates [6] or through conversion of 3-oxo-5-phenyl-pent-4-enoic acid methyl ester with oxalate [7]. Otherwise, in the multi-step synthesis of the natural product ABT-418 [8] the title compound was synthesized as an important intermediate. The double bond in the titlemolecule adopts a trans configuration with a torsion angle of almost 180° (178.09(1)°). The aromatic system, the double bonds and the carbonyl group at C11 form a conjugated '-system. Due to the conjugation with the carbonyl groups the double bond is activated, hence substrate addition follows in a regioselective manner. The length of the bond C95C10 (1.336(3)Å) is in the range of typical C5C double bonds. Otherwise, the C9—O3 distance (1.342(2) Å) corresponds to a C—O single bond. An intramolecular hydrogen bond is found between the OH group at C9 and the adjacent carboxyl group. In solution this compound shows keto-enol tautorism (20:80 ratio ratified by NMRmeasurement [2]). The refinement of the occupation of the H3B site shows, that the enolic form is preferred in the crystalline solid state. Z. Kristallogr. NCS 223 (2008) 19-20 / DOI 10.1524/ncrs.2008.0009 19 © by Oldenbourg Wissenschaftsverlag, München Crystal: colorless needle, size 0.11 × 0.15 × 2.00 mm Wavelength: Mo K4 radiation (0.71073 Å) *: 0.92 cm−1 Diffractometer, scan mode: Bruker SMART APEX CCD, ./6 2%max: 54.5° N(hkl)measured, N(hkl)unique: 19156, 2336 Criterion for Iobs, N(hkl)gt: Iobs > 2 #(Iobs), 1207 N(param)refined: 173 Programs: SHELXS-97 [9], SHELXL-97 [10] Table 1. Data collection and handling. H(1) 4e 0.911(3) 0.108(4) 0.833(1) 0.088 H(2) 4e 0.876(3) −0.177(5) 0.753(1) 0.089 H(3A) 4e 0.708(2) −0.119(4) 0.659(1) 0.080 H(5) 4e 0.596(2) 0.491(5) 0.730(1) 0.079 H(6) 4e 0.762(2) 0.459(4) 0.826(1) 0.090 H(7) 4e 0.515(2) 0.084(4) 0.597(1) 0.071 H(8) 4e 0.465(2) 0.539(4) 0.629(1) 0.069 H(3B) 4e 0.270(3) 0.231(6) 0.479(2) 0.120 H(10) 4e 0.308(2) 0.729(4) 0.549(1) 0.070 H(12A) 4e −0.065(3) 0.741(6) 0.418(2) 0.115 H(12B) 4e 0.055(3) 0.770(5) 0.361(2) 0.115 H(12C) 4e −0.007(3) 0.975(6) 0.403(2) 0.115 Table 2. Atomic coordinates and displacement parameters (in Å). Atom Site x y z Uiso