Non-biaryl atropisomers derived from carbohydrates. Part 1. Stereoselective synthesis of 1-aryl-5-hydroxyimidazolidine-2-thiones and their transformation into imidazoline-2-thiones

A series of chiral 5-hydroxyimidazolidine-2-thiones bearing an ortho-substi tuted aromatic residue at N-1, which are readily accessible from D-glucosam ine, have been synthesized as potential atropisomers. In general, these sub stances display a trans arrangement between H-4 and H-5, and hence the abso lute configuration at C-5 was shown to be R. However the first example of t his type of structures having a cis configuration (S at C-5) is also descri bed. Moreover, the mechanistic features associated with the conversion of 5 -acetoxyimidazolidine-2-thiones into imidazoline-2-thiones have also been e valuated. (C) 1999 Elsevier Science Ltd. All rights reserved.