Utilization of Sugars in Organic Synthesis. Part XXXIII. Thio-Sugars III. Radical Catalyzed Thione-Thiol Rearrangement of Cyclic Thionocarbonates on a Pyranose Ring: Formation of cis-Arranged Cyclic Thiolcarbonates.
作者:Yoshisuke TSUDA、Shinsuke NOGUCHI、Kimihiro KANEMITSU、Yoshiyuki SATO、Kyoko KAKIMOTO、Yumiko IWAKURA、Shinzo HOSOI
DOI:10.1248/cpb.45.971
日期:——
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.
吡喃糖苷 3, 4-顺式硫代碳酸酯在自由基促进的反应条件下(方法 A、B 或 C,如本文所述)以可接受的产率生成 O-S 重排产物,即顺式立体化学的 3, 4-硫醇碳酸酯。2在方法B(用六丁基二锡烷光解)中,反式立体化学的3-硫代碳酸酯也优先产生顺式立体化学的重排产物。尽管在大多数情况下产物的区域控制并不令人满意,但一些结果表明反应的区域选择性明显受到底物异头位置的立体化学的影响。通过常规方法将产物转化为硫代糖苷(全乙酸盐形式)。