Efficient synthesis of β-halogeno protected l-alanines and their β-phosphonium derivatives
作者:Franck Meyer、Abdelhamid Laaziri、Anna Maria Papini、Jacques Uziel、Sylvain Jugé
DOI:10.1016/s0957-4166(03)00484-1
日期:2003.8
furnished the corresponding β-halogeno-N-benzoyl-α-amino acids in 70–95% yields. Quaternization of triphenylphosphine by the bromo or iodo derivatives led to the phosphonium salts bearing a free acid function in 95% yield, without racemization. The efficiency of this synthesis was demonstrated by the preparation of these phosphonium salts in excellent overall yields, by a one-pot procedure starting from the
由1-丝氨酸制备的恶唑啉与三甲基甲硅烷基卤化物(TMSX)的开环导致β-卤代-N-苯甲酰基-α-氨基酯的产率高至优异。β-溴或-碘氨基酯对三苯膦进行季铵化可得到相应的β-salts盐,总收率可达93%,ee≥96%。酯官能团的水解得到带有N-苯甲酰基-α-氨基酸取代基的phospho盐,具有部分消旋作用。但是,TMSX与羧酸盐的反应是通过将起始的恶唑啉酯皂化而制备的,提供了相应的β-卤代-N-苯甲酰基-α-氨基酸,产率为70-95%。三苯基膦被溴或碘衍生物季铵化导致ization盐具有游离酸功能,产率为95%,而没有外消旋作用。通过从恶唑啉开始的一锅法以极好的总收率制备这些phospho盐,证明了这种合成的效率。