Rearrangement of lithiated S-alkyl O,O-dialkyl thiophosphates: Scope and stereochemistry of the thiophosphate–mercaptophosphonate rearrangement
作者:Violeta Philippitsch、Friedrich Hammerschmidt
DOI:10.1039/c1ob05246b
日期:——
S-Alkyl O,O-dialkyl thiophosphates are prepared by alkylation of the triethylammonium salt of O,O-diisopropyl thiophosphoric acid. S-Benzyl thiophosphate was metallated at temperatures of ≥−45 °C by trityllithium and LiTMP (lithium 2,2,6,6-tetramethylpiperidide) and S-alkyl thiophosphates only by LiTMP to give dipole-stabilised carbanions which rearrange to α-mercaptophosphonates in yields of up to
S-烷基O,O-二烷基硫代磷酸酯是通过将O,O-二异丙基硫代磷酸的三乙铵盐烷基化而制得的。S-苄基硫代磷酸酯在≥−45°C的温度下被金属化三苯甲基锂仅通过LiTMP和LiTMP(2,2,6,6-四甲基锂化锂)和S-烷基硫代磷酸酯才能得到偶极稳定的碳负离子,这些碳负离子可以重排为α-巯基膦酸酯,产率最高可达45%。发生金属化时具有很高的初级动力学同位素效应(k H / k D高达≈50)。当使用(R)-N-异丙基-1-苯基乙基氨基锂诱导S-戊基硫代磷酸酯的异构化时,分离出ee值为22%的α-巯基膦酸酯。(R)-S- [1-D 1 ]己基O,O-二异丙基硫代磷酸酯被重排为右旋α-巯基-[1-D 1 ]己基膦酸酯,其(R)-构型由化学相关性确定。硫代磷酸酯-巯基膦酸酯的重排在保留构型的情况下进行。