Regio- and stereoselective reactions of a rhodanine derivative with optically active 2-methyl- and 2-phenyloxirane

The reaction of a rhodanine derivative (= (Z)-5-benzylidene-3-phenyl-2-thioxo-1,3-thiazolidin4-one; 1) with (S)-2-methyl-oxirane (2) in the presence of SiO2 in dry CH2Cl2 for 10 days led to two diastereoisomeric spirocyclic 1,3-oxathiolanes 3 and 4 with the Me group at C(2) (Scheme 2). The analogous reaction of 1 with (R)-2-phenyloxirane (5) afforded also two diastereoisomeric spirocyclic 1,3oxathiolanes 6 and 7 bearing the Ph group at C(3) (Scheme 3). The structures of 3, 4, 6, and 7 were confirmed by X-ray crystallography (Figs. 1 and 2). These results show that oxiranes react selectively with the thiocarbonyl group (C=S) in 1. Furthermore, the nucleophilic attack of the thiocarbonyl Satom at the SiO2-activated oxirane ring proceeds with high regioand stereoselectivity via an SN2-type mechanism. DOI: https://doi.org/10.1016/j.tet.2004.04.066 Posted at the Zurich Open Repository and Archive, University of Zurich ZORA URL: https://doi.org/10.5167/uzh-79824 Originally published at: Fu, Changchun; Thrane, Marie V; Linden, Anthony; Heimgartner, Heinz (2004). Regioand stereoselective reactions of a rhodanine derivative with optically active 2-methyland 2-phenyloxirane. Tetrahedron, 60:5407-5412. DOI: https://doi.org/10.1016/j.tet.2004.04.066