作者:Jessica F. Sonnenberg、Alan J. Lough、Robert H. Morris
DOI:10.1021/om5008083
日期:2014.11.24
precatalysts for the asymmetric direct hydrogenation of ketones and imines. Employing related ligand scaffolds, we successfully generated and tested the series of three new precatalysts [Fe(PCy2CH2CH═NCH(R)CH2PPh2)(CO)2Br]BF4 with chirality derived from (S)-amino alcohols with phenyl, benzyl, and isopropyl substituents (R), yielding fairly active and selective systems. For the reduction of acetophenone to (S)-1-phenylethanol
已知类型为mer,反式-[Fe(PNP')(CO)2 Br] BF 4的配合物是酮和亚胺不对称直接加氢的前催化剂。采用相关配体的支架,我们成功地产生并测试了一系列的三个新的预催化剂的[Fe(PCY 2 CH 2 CH = NCH(R)CH 2 PPH 2)(CO)2 BR] BF 4与手性从(派生小号) -具有苯基,苄基和异丙基取代基(R)的氨基醇,可产生相当活泼和选择性的系统。用于将苯乙酮还原为(S)-1-苯基乙醇的周转频率长达920小时在50°C和5-25 atm的H 2下,获得了–1和高达74%的对映体过量。然而,我们发现,将这些大的基团R置于氮旁边被发现对催化活性有害。为了扩展配体结构的范围,我们从邻二苯基膦基苯甲醛和膦胺PPh 2 CHR 1 CHR 2 NH 2(R 1 = H,Ph ,CH 2 PH,用的iPr - [R 2 = H或R 1 = Me中,pH值- [R 2 =