Catalyst-Controlled Diastereoselection in the Hydrogenation of Heterocycloalkyl Ketones
作者:Masaya Akashi、Noriyoshi Arai、Tsutomu Inoue、Takeshi Ohkuma
DOI:10.1002/adsc.201100398
日期:2011.8
α-Substituted chiral ketones that have small steric and electronic differences around the reaction sites are difficult substrates to reduce with high diastereoselectivity. Metal hydride reduction of 2-(4-benzoylmorpholinyl) phenyl ketone and 3-(1-tert-butoxycarbonylpiperidinyl) phenyl ketone using sodium borohydride, zinc borohydride, and potassium tri-sec-butylborohydride as reducing agents affords
在反应位点附近具有小的空间和电子差异的α-取代的手性酮是难以以高非对映选择性还原的底物。使用硼氢化钠,硼氢化锌和三仲丁基硼氢化钾作为还原剂,对2-(4-苯甲酰基吗啉基)苯基酮和3-(1-叔丁氧基羰基哌啶基)苯基酮进行金属氢化物还原,可制得顺式和反式醇比例低于80:20。这些酮用的RuCl的催化剂体系的加氢2(BIPHEP)(DMEN)和氢叔在2-丙醇结果丁醇顺选择性≥99:1的醇[BIPHEP = 2,2'-双(二苯基膦基)联苯,DMEN = N,N-二甲基乙二胺]。非对映选择性的显着差异表明该氢化反应中的立体选择主要由催化剂反应场的结构(“催化剂控制的非对映选择性”)调节,而不是由底物的内部立体控制。该化学是通过动态动力学拆分用的RuCl施加到不对称氢化2 - [(小号)-BINAP] [([R)-DMAPEN] /钾叔-丁氧化物催化剂[BINAP = 2,2'-双(二苯基膦基)-1,1'-联萘基,DMAPEN