Structure of 2-oxo-4-thiazolidinecarboxylic acid

Abstract

C4HsNO3S , Mr = 147.15, orthorhombic, P212~2~, a = 5.968 (3), b = 17.945 (3), c = 5.387 (3) A, V= 576.9 (4) A 3, Z = 4, Ox = 1.69 g cm -3, a(Mo Ka) = 0.71069 ,~,/.i, = 4.63 cm-~, F(000) = 304, T = 296 K, R = 0.034 for 730 reflec- tions with I > 2.500-(/). Hydrogen bonds NH...O z C(carboxyl) 2.96 and OH...OzC(carbony l) 2-62 A afford a sheet structure. A signal 4-4 times that of quartz is observed in an optical second-harmonic test. Introduction. The methyl ester of the title compound was prepared as an intermediate in the total synthesis of latrunculin A (White & Kawasaki, 1990). The hydrolyzed ester contains a high density of chromo- phores of interest for optical frequency conversion at short wavelengths and so crystals were grown to determine the structure and efficiency of second- harmonic generation. Experimental. The compound was obtained by acid hydrolysis of the corresponding methyl ester fol- lowing a known procedure (Maclaren, 1968). Crys- tals were grown by slow evaporation of an aqueous solution. A block of dimensions 0-25 × 0.30 × 0.25 mm was mounted on a glass fiber and used for collection of data on a Rigaku AFC6R diffractom- eter. Unit-cell parameters were refined by least- squares analysis of the angle settings of 16 reflections in the range 30.5 2-5o'(1) were obtained. All calculations were performed on a MicroVAX II computer with programs from the TEXSAN crys- tallographic software package (Molecular Structure Corporation, 1989). Atomic scattering factors were taken from International Tables for X-ray Crystallog- raphy (1974, Vol. IV). Atomic positions were obtain- 0108-2701/91/071481-02503.00 ed using the direct-methods program MITHRIL (Gilmore, 1984). H atoms bound to C atoms were placed in calculated positions (C--H = 0.95 A) and assigned isotropic thermal parameters of 1.5 x Beq of the associated C atom. The remaining H atoms were located in a difference electron density map. Posi- tional parameters and the isotropic thermal param- eter were subsequently refined for each of these H atoms. Minimization of the function Zw(Fo- Fc) 2 (where w = 1/0.2(Fo)) with those data having I> 2.50(/) using 90 variables and 730 observations affords the residuals R = 0.034, wR = 0-045 and the indicator S = 1-79. In the final cycle of refinement A/0.=0.01. The maximum feature in the final difference electron density map was 0.21 e/~-3. The enantiomorphs are indistinguishable from the X-ray data. Fractional atomic coordinates and isotropic temperature coefficients are given in Table 1.*