Synthesis of Optically Pure Compounds by Enantiotopically Differentiating Monoacetalization of Prochiral Diketones. Part II. Fragmentation of ?-Keto-Acetals
作者:Rudolf O. Duthaler、Peter Maienfisch
DOI:10.1002/hlca.19840670324
日期:1984.5.2
sulfonate counter-ion. Application of this reaction to the diastereomeric monoacetals 3 and 4, derived from cis-9-methyl-decalin-1,8-dione (1), followed by transesterification with CH3OH, yields optically pure 4-(2′-methyl-3′-oxocyclohexyl)butyrate 9 ((+)−9 from 3, (−)-9 from 4) and the monosulfonate of Meso-2,3-butanediol (−)-13 (Scheme 2). Unexpectedly, this cleavage proceeds as well with monoacetal
在沸腾的苯中,用磺酸处理平滑不可逆的克莱森型裂解中的衍生自不可烯丙基β-二酮的β-酮缩醛。缩醛-C-原子由此通过二烷氧基碳鎓离子转化为羧酸酯,该二烷氧基碳鎓离子被磺酸根抗衡离子去烷基化。将此反应应用于衍生自顺式-9-甲基-十氢化萘-1,8-二酮(1)的非对映体单缩醛3和4,然后与CH 3 OH进行酯交换,生成光学纯的4-(2'-甲基- 3'-氧代环己基)丁酸酯9((+)- 9从3,(-)- 9从4)和的单磺酸盐内消旋-2,3-丁二醇( - ) - 13(方案2) 。出乎意料的是,这种切割也与单缩醛26一起进行,该单缩醛26是通过将反式-9-甲基十氢化萘-1,8-二酮(27)与2,2-二甲基-1,3-丙二醇缩醛化而获得的(方案7)。一些尝试,瞄准的异构化顺式-和反式-decalin衍生物3和24,或25和26,通过在假定的carboxonium中间,没有成功。