at position 4 and of the alpha-methyl substituent of (R)-N-benzyl-N-alpha-methylbenzylamine on the reactivity were also studied and, upon application of a chiral amine, excellent stereoselectivity of the conjugate addition was observed. Amino ester 11 was obtained as a single product and transformed to the corresponding amino acids 10A and 10D in good yields on the gram scale.
二苄胺在(+)-叔丁基叔丁基酸酯(3)和(+)叔丁基叔丁基酸酯(6)上的迈克尔加成反应产生非对映异构体β -
氨基酯7A-D在中等立体定向反应中的比例为76:17:6:1。分离非对映异构体后,将主要产物顺式异构体7A定量异构化为次要成分反式
氨基酯7D。所有四个异构体均被转化为相应的β-
氨基酸10A-D,这是有望在三步中合成β-肽和1,3-杂环的基础材料。还研究了位置4上的异丙基和(R)-N-苄基-N-α-甲基苄基胺的α-甲基取代基的空间反应性,并且在应用手性胺后,观察到缀合物添加的极好的立体选择性。获得的
氨基酸酯11为单一产物,并以克为单位以良好的产率转化为相应的
氨基酸10A和10D。