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.
Enantioselective Total Synthesis of (+)-Hagen's Gland Lactones
作者:Santosh J. Gharpure、Laxmi Narayan Nanda、Manoj Kumar Shukla
DOI:10.1002/ejoc.201101328
日期:2011.11
Enantioselectivesynthesis of Hagen's gland lactone is described. The enantiomerically enriched diol was prepared by organocatalytic α-oxidation of the aldehyde. The other key reactions involved a highly diastereoselective intramolecular cyclopropanation of vinylogous carbonates to furnish donor–acceptor-substituted cyclopropanes and their ring opening and iodolactonization followed by reduction.
Asymmetric Protonation of Cumulenolates: Synthesis of Allenyl Aldehydes Facilitated by an Organomanganese Auxiliary
作者:Animesh Roy、Bilal A. Bhat、Salvatore D. Lepore
DOI:10.1021/acs.orglett.5b03681
日期:2016.3.18
Chiral ammonium salts were used to catalyze the isomerization of organomanganese-complexed alkynyl aldehydes to chiral allenal building blocks in moderate to good enantiomericexcesses. Normally, conjugated alkynyl aldehydes do not isomerize to their thermodynamically less stable allene isomers. However, with a manganese auxiliary in place to promote allene formation, asymmetric protonation of cumulenolate