Thio-Sugars III. Radical Catalyzed Thione-Thiol Rearrangement of Cyclic Thionocarbonates on a Pyranose Ring : Formation of cis-Arranged Cyclic Thiolcarbonates

Abstract

Pyranoside 3, 4-cis-thionocarbonates, under radical-promoted reaction conditions (method A, B, or C, described in the text), gave O-S rearrangement products, 3, 4-thiolcarbonates of cis-stereochemistry, in accepTable yields.2, 3-Thionocarbonates of trans-stereochemistry also gave the rearrangement products of cis-stereochemistry preferentially in method B (photolysis with hexabutyldistannane). Although regio-control of the product was not satisfactory in most cases, some of the results suggested that the regioselectivity of the reaction is markedly influenced by the stereochemistry of the anomeric position of the substrates. The products were converted to thioglycosides(peracetate forms) by conventional means.