Synthesis of Ro 25-8210 via an enantioselective oxazaborolidine-catalyzed reduction
作者:Kenneth G. Hull、Mike Visnick、William Tautz、Allen Sheffron
DOI:10.1016/s0040-4020(97)00802-8
日期:1997.9
Prochiral ketones which contain nitrogen atoms have been reduced enantioselectively with chiral oxazaborolidines in the presence of excess borane. However, the pyridine system has been shown to be a poor substrate for this asymmetric reduction. For example, catalytic reduction of 2-acetylpyridine with a chiral oxazaborolidine provided the product alcohol in only 28% ee. We wish to report the enantioselective
在过量的硼烷存在下,用手性恶唑硼烷环烷对映异构地还原了含有氮原子的前手性酮。然而,对于这种不对称还原,吡啶体系已被证明是较差的底物。例如,用手性恶唑硼烷催化还原2-乙酰基吡啶仅提供28%ee的产物醇。我们希望报道手性恶唑硼烷啶对2-(溴乙酰基)-吡啶1的对映选择性还原。还原得到良好的对映体过量(80%ee),重结晶后可提高到≥95%ee。随后,使用溴代醇6制备Ro 25-8210。