Structure of 3-isopropyl-5-phenyl-thiazolidin-4-one-2-thione

Abstract

Results from X-ray diffraction determination have shown that (IS,2E,4R,6R, 7E.l1.5, and (IS,2E,4s,6R,7E,7,6, exist as ~onformT3s A and B about the 5,6-bond. An analysis of the Hand C NMR spectra suggests that these conformations are retained in solution and that other cembranold alcohols or acetates are conformationally reminiscent of either 1 or 2. \He have now carried out molecular mechanics (MM2) calculations using X-ray data of 1 and 2 as Inputs. These show that for each compound, the geometry at the local energy minimum Is close to that existing In the crystalline state. Futher calculations using the dihedral driver of MM2 varying the 4,5,6,7 dihedral angle Indicate that both I and 2 have tloJO local energy minima occupied by conformers of types A and B respect I ve I y. Bond lengths and angles in the thiazolidinone-thione part agree well with recent data for 5-methyl-thiazolidin-2--one-4-thione (Gattow et al., Z. anorg. Allg. Chem. 506 (1983) 145). The orientation of the 3-isopropyl group-Ts as expected from steric considerations.