Regio- and Stereoselective Biocatalytic Monoamination of a Triketone Enables Asymmetric Synthesis of Both Enantiomers of the Pyrrolizidine Alkaloid Xenovenine Employing Transaminases
作者:Stefan E. Payer、Joerg H. Schrittwieser、Barbara Grischek、Robert C. Simon、Wolfgang Kroutil
DOI:10.1002/adsc.201500781
日期:2016.2.4
well as the (−)‐enantiomer of the pyrrolizidine alkaloid xenovenine were prepared within five steps with 17 and 30% overall yields, respectively, in optically pure form, >99% ee as well as >99% de. In the asymmetric key step a transaminase performed a regio‐ and stereoselective monoamination of a triketone. By employing two enantiocomplementary transaminases from Arthrobacter sp. both enantiomers were
的(+) -以及( - ) -的双吡咯烷类生物碱xenovenine的对映异构体分别在五个步骤来制备:用17和30%的总产率,光学纯形式,> 99%ee值以及> 99%德。在不对称关键步骤中,转氨酶对三酮进行了区域和立体选择性单胺化。通过使用来自节杆菌属的两种对映体互补转氨酶。两种对映异构体都是可及的。从市售的非手性2-(正庚基)呋喃开始,可通过两个步骤轻松制备三酮。在最后的催化加氢步骤中,新引入的手性中心引导氢加成,优先形成所需的(5 Z,8E)-非对映异构体。在三个酮中,单个酮部分进行了区域和立体选择性胺化,从而可以在不需要保护策略的情况下,以最短和最高的产率进行双环展示吡咯并立烷生物碱的全合成。