Stereoselective synthesis of allylic amines by rearrangement of allylic trifluoroacetimidates: stereoselective synthesis of polyoxamic acid and derivatives of other α-amino acids
作者:Ian Savage、Eric J. Thomas、Peter D. Wilson
DOI:10.1039/a905772b
日期:——
On heating in xylene under reflux, allylic trifluoroacetimidates undergo [3,3] sigmatropic rearrangement to regioisomeric allylic trifluoroacetamides. Examples include the rearrangements of the trifluoroacetimidates 16 and 73 to the trifluoroacetamides 17 and 74, which were incorporated into stereoselective syntheses of polyoxamic acid 1, and the rearrangement of the trifluoroacetimidate 26. The rearrangement was the key step in asymmetric syntheses of the (S)- and (R)-valine derivatives 37 and 48. Other examples include rearrangements of the trifluoroacetimidates 52, 54 and 56 prepared from geraniol, cinnamyl alcohol and sorbyl alcohol, respectively, and the more complex trifluoroacetimidates 62 and 69. The stereoselectivity of these rearrangements, which are somewhat faster than rearrangements of analogous allylic trichloroacetimidates, is consistent with the participation of chair-like, six-membered, transition structures.
在甲苯中回流加热时,烯丙基三氟乙亚胺酸酯会发生[3,3] σ迁移重排,生成区域异构的烯丙基三氟乙酰胺。例如,三氟乙亚胺酸酯16和73重排生成三氟乙酰胺17和74,这些被用于合成聚氧基酸1的选择性合成中,以及三氟乙亚胺酸酯26的重排。这一重排是对映选择性合成(S)-和(R)-缬氨酸类似物37和48的关键步骤。其他例子包括由香叶醇、肉桂醇和苏儿醇分别制备的三氟乙亚胺酸酯52、54和56的重排,以及更复杂的三氟乙亚胺酸酯62和69的重排。这些重排的立体选择性比类似的烯丙基三氯乙亚胺酸酯重排稍快,与椅式六元过渡态结构的参与相符。