A New Strategy for the Synthesis of α-Difluoromethyl-Substituted α-Hydroxy and α-Amino Acids
作者:Sergey N. Osipov、Alexander S. Golubev、Norbert Sewald、Thomas Michel、Alexey F. Kolomiets、Alexander V. Fokin、Klaus Burger
DOI:10.1021/jo9608331
日期:1996.1.1
A new method for the preparation of alpha-chlorodifluoromethyl-, alpha-bromodifluoromethyl-, and alpha-difluoromethyl-substituted alpha-hydroxy and alpha-amino acid esters 11, 19-21 is described. The key step of the synthesis is the regioselective alkylation of ketones 5, 7-9 and imines 16-18 with C-nucleophiles. The ketones 7-9 are readily available from 3,3,3-trifluorolactate 1 by a five-step procedure
描述了一种制备α-氯二氟甲基,α-溴二氟甲基和α-二氟甲基取代的α-羟基和α-氨基酸酯11、19-21的新方法。合成的关键步骤是用C-亲核试剂对酮5、7-9和亚胺16-18进行区域选择性烷基化。酮7-9可通过五步法容易地从3,3,3-三氟乳酸酯1获得。随后从19-21除去保护基团提供相应的游离氨基酸25、26、28。