Electrophilic ring opening of oxazolines derived from serine and threonine: A practical entry to N(N)-protected β-halogeno α-aminoesters
作者:Abdelhamid Laaziri、Jacques Uziel、Sylvain Jugé
DOI:10.1016/s0957-4166(98)00002-0
日期:1998.2
Treatment of oxazolines 4a–c derived from serine or threonine with chloroformates, leads to the oxazoline ring opening and to the formation of N,N-protected β-chloro-α-aminoesters 1a–e in 30–88% isolated yields. In the presence of NaI (0.9 equiv), oxazolines 4a,b,d react with ethyl chloroformate to afford the N,N-protected β-iodo α-amino esters 1f–h (67–89% yields), whereas the reaction of 4a,b with
用氯甲酸酯处理衍生自丝氨酸或苏氨酸的恶唑啉4a – c,导致恶唑啉开环并形成N,N保护的β-氯-α-氨基酯1a – e,分离产率为30–88%。在NaI(0.9当量)存在下,恶唑啉4a,b,d与氯甲酸乙酯反应,得到N,N保护的β-碘α-氨基酯1f–h(67–89%的收率),而4a,b和三甲基甲硅烷基卤化物可得到类似的N-苯甲酰基β-卤代衍生物1i,k,产率为30-86%。