Huang Xiaogen, Craita Cotinica, Vogel Pierre
Laboratory of Glycochemistry and Asymmetric Synthesis, Swiss Federal Institute of Technology, EPFL-BCH, CH-1015 Lausanne-Dorigny, Switzerland.
J Org Chem. 2004 Jun 11;69(12):4272-5. doi: 10.1021/jo0357622.
At low temperature, 1-alkoxy-1,3-dienes add to sulfur dioxide activated by a Lewis or protic acid generating zwitterionic intermediates that can be quenched by enoxysilanes. The resulting beta,gamma-unsaturated silyl sulfinates can be desilylated by 1:1 Pd(OAc)(2)/PPh(3) catalyst, liberating the corresponding beta,gamma-unsaturated sulfinic acids that undergo smooth and highly stereoselective retro-ene eliminations of sulfur dioxide. The method has been applied to generate enantiomerically pure polypropionate fragments.
在低温下,1-烷氧基-1,3-二烯与由路易斯酸或质子酸活化的二氧化硫加成,生成两性离子中间体,该中间体可被烯氧基硅烷淬灭。所得的β,γ-不饱和甲硅烷基亚磺酸盐可通过1:1的Pd(OAc)₂/PPh₃催化剂进行脱硅基化反应,释放出相应的β,γ-不饱和亚磺酸,这些亚磺酸会顺利地进行高度立体选择性的二氧化硫逆烯消除反应。该方法已被用于生成对映体纯的聚丙酸酯片段。