作者:Farina Brackmann、Heiko Schill、Armin de Meijere
DOI:10.1002/chem.200500384
日期:2005.11.4
Protected racemic and enantiomerically pure 3,4-(aminomethano)prolines rac-9 and (2S,2'R,3R,4R)-9 have been prepared applying a titanium-mediated reductive cyclopropanation as a key step. Thus, cyclopropanations of N,N-dibenzylformamide with titanacyclopropanes generated in situ from racemic or enantiomerically pure tert-butyl N-Boc-3,4-dehydroprolinates rac-8 or (S)-8 proceed diastereoselectively
使用钛介导的还原性环丙烷化作为关键步骤,已制备了受保护的外消旋和对映体纯的3,4-(氨基甲氨基)脯氨酸rac-9和(2S,2'R,3R,4R)-9。因此,N,N-二苄基甲酰胺与由外消旋或对映体纯的叔丁基N-Boc-3,4-脱氢脯氨酸酯rac-8或(S)-8原位生成的钛环丙烷的环丙烷非对映选择性地进行,并提供受保护的外消旋和对映体纯的二氨基酸9.后者被掺入三个包含甘氨酰基,丙氨酰基和苯丙氨酰基部分的三肽中。