5<i>H</i>-Oxazol-4-ones as Building Blocks for Asymmetric Synthesis of α-Hydroxycarboxylic Acid Derivatives
作者:Barry M. Trost、Kalindi Dogra、Maurizio Franzini
DOI:10.1021/ja031539a
日期:2004.2.1
little-known heterocyclic ring system, are readily available via a microwave-assisted, sodium fluoride catalyst cyclization of mono-alpha-haloimides, which in turn are accessed by N-acylation of benzamides with alpha-bromo acid halides. Terminally substituted allyl systems serve as excellent substrates for Mo-catalyzed asymmetric allylic alkylation. The resultant products are formed with excellent ees involving
5H-烷基-2-苯基-恶唑-4-酮是一种鲜为人知的杂环系统,可通过微波辅助的氟化钠催化剂环化单-α-卤代酰亚胺轻松获得,而后者又可通过 N-用α-溴酰卤酰化苯甲酰胺。末端取代的烯丙基体系可作为 Mo 催化的不对称烯丙基烷基化的优良底物。生成的产物具有优异的 ee,包括衍生自反式-1,2-二氨基环己烷的 N,N'-双-吡啶甲酰胺和三(羰基)环庚三烯钼的催化剂。除了苯类之外,烯丙基碳酸酯部分上的非苯类芳香族和乙烯基取代基提供了良好到优异的区域选择性和非对映选择性以及优异的对映选择性。杂环上的取代基包括甲基、正丁基、烯丙基、异丁基、异丙基和环己基。产品中双键的存在允许它们通过双键的化学性质进一步修饰,包括复分解。产物在碱性条件下水解以提供α-羟基酰胺。