The stereoselectivesynthesis of (−)-protoemetinol has been accomplished through nine steps from a known homoallylic amine. The key steps of the synthesis involve the efficient preparation of an aza-Claisen rearrangement (ACR) precursor using cross metathesis and amide enolate-induced ACR followed by acid-catalyzed transannulation for the elaboration of the benzo[α]quinolizine skeleton and three stereogenic
Organo-Manganese η<sup>2</sup>-Auxiliary Directed Reactions: A Diastereoselective Approach to 2,3-Allenols
作者:Animesh Roy、Bilal A. Bhat、Salvatore D. Lepore
DOI:10.1021/ol503757h
日期:2015.2.20
Propargyl aldehydes underwent isomerization to allenyl aldehydes under mildly basic conditions when complexed to an organo-manganese auxiliary using methylcyclopentadienyl manganese tricarbonyl (MMT). This traceless auxiliary magnifies the axial chirality of the allene moiety, allowing for highly diastereoselective additions to the aldehyde carbonyl and subsequent access to an array of 2,3-allenols. Using this strategy, a nitrile-substituted 2,3-allenol was prepared and efficiently converted to Hagens gland lactone.