Stannyl Radical-Mediated Cleavage of π-Deficient Heterocyclic Sulfones. Synthesis of α-Fluoro Esters
作者:Stanislaw F. Wnuk、Jeannette M. Rios、Jahanzeb Khan、Ya-Li Hsu
DOI:10.1021/jo000342n
日期:2000.6.1
1 h under these conditions. This represents a mild new methodology for removal of the synthetically useful sulfone moiety. Substitution of Bu(3)SnD for Bu(3)SnH gave access to alpha-deuterium-labeled esters. Treatment of the alpha-(pyrimidin-2-ylsulfonyl) enolates derived from several esters with Selectfluor gave high yields of the 2-fluoro-2-(pyrimidin-2-ylsulfonyl)alkanoates, which were smoothly
用三丁基锡烷和偶氮双(2-甲基-2-丙腈)(AIBN)在苯中回流处理2-(吡啶-2-基磺酰基)己酸乙酯36小时,导致氢解生成己酸乙酯(60%),而没有回流48小时后,观察到与2-(苯磺酰基)己酸乙酯反应。在这些条件下,在1小时内对2-(嘧啶-2-基磺酰基)己酸乙酯进行定量氢解。这代表了去除合成上有用的砜部分的温和的新方法。用Bu(3)SnD代替Bu(3)SnH可以访问α-氘标记的酯。用Selectfluor处理衍生自几种酯的α-(嘧啶-2-基磺酰基)烯醇酸酯,可高产率地生产2-氟-2-(嘧啶-2-基磺酰基)链烷酸酯,将其平滑地进行磺酰化[Bu(3)SnH(2当量)/ AIBN /苯/δ],得到2-氟链烷酸酯。在氟化钾的存在下,由氯化三苯甲基氯化锡(0.15当量)和过量的聚甲基氢硅氧烷生成的“催化”氢化锡,还以高收率实现了从酸衍生物中去除pi不足的α-(嘧啶-2-基磺酰基)部分。建议通过烷氧基酮基型自由基和烯醇锡进行脱磺酰化。