CHIRAL ACETYLENE THIOETHERS - SYNTHESIS AND PAUSON-KHAND REACTIONS

Chiral acetylene thioethers have been prepared in excellent yields fro m the corresponding thiols. The procedure involves the treatment of th e corresponding thiolate with 2-bromo-1,1-diethoxyethane followed by d ouble elimination with LDA and, in some cases, alkylation of the acety lide with alkyl or omega-alkenyl iodides. These compounds have been te sted in both intra- and intermolecular Pauson-Khand reactions. This st udy clearly shows that acetylenic thioethers can be excellent substrat es for asymmetric versions of this reaction. (C) 1997 Elsevier Science Ltd.