Regiospecific vinyl phosphate/β-keto phosphonate rearrangements initiated by halogen-metal exchange
Regiospecific vinyl phosphate/β-keto phosphonate rearrangements initiated by halogen-metal exchange
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DOI：
10.1021/jo972131x
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发表时间：
1998-04-17
影响因子：
3.6
通讯作者：
Wiemer, DF
中科院分区：
文献类型：
--
作者：
Baker, TJ;Wiemer, DF
通过卤素-金属交换诱导2-溴乙烯基磷酸盐的1，3-磷迁移反应，开发了一种制备β-酮基膦酸酯的新方法。这些中间体可以通过与强碱反应将α-溴酮转化为适当的烯酸酯来制备，或者通过与α-溴α，β-不饱和酮的共轭加成来制备。在任何一种情况下，通过与二烷基磷氯酸酯反应捕获生成的烯醇，得到2-溴乙烯基磷酸酯。金属化可以在n-BuLi处理后完成，一旦实现金属化，重排就很容易。对同位素标记底物的研究表明，这种重排是区域特异性的，而不是由强碱引起的磷酸乙烯酯/β-酮基膦酸重排，有时会得到区域异构体产物。
A new strategy has been developed for preparation of beta-keto phosphonates via a halogen-metal exchange induced 1,3-phosphorus migration of 2-bromovinyl phosphates. These intermediates can be prepared through conversion of an alpha-bromo ketone to the appropriate enolate by reaction with strong base, or through conjugate addition to an alpha-bromo alpha,beta-unsaturated ketone. In either case, trapping the resulting enolate by reaction with a dialkyl phosphorochloridate gives the 2-bromovinyl phosphate. Metalation can be accomplished upon treatment with n-BuLi, and rearrangement is facile once metalation has been achieved. Studies with isotopically labeled substrates have shown that this rearrangement is regiospecific, in contrast to vinyl phosphate/beta-keto phosphonate rearrangements induced by strong base where regioisomeric products are sometimes obtained.