BiBr3 initiated cyclization–addition reactions: effect of π-nucleophile on oxocarbenium ion addition and total syntheses of (+)-(S,S)-(cis-6-methyltetrahydropyran-2-yl)acetic acid and its trans-diastereomer
作者:Robert J. Hinkle、Yajing Lian、Nichole D. Litvinas、Alex T. Jenkins、Daniel C. Burnette
DOI:10.1016/j.tet.2005.09.045
日期:2005.12
initiated tandem cyclization–additions of very reactive silylketeneacetal nucleophiles with δ-silyloxy aldehydes to afford 2,6-disubstituted THP products, diastereoselectivities range from 5–6:1 (trans-/cis-). The selectivity for axial attack on the intermediate oxocarbenium ion is inversely proportional to π-nucleophilicity. We have utilized this chemistry to convert a common starting material to both cis-
Diastereoselective Synthesis of Dihydropyrans via Prins Cyclization of Enol Ethers: Total Asymmetric Synthesis of (+)-Civet Cat Compound
作者:Sabera Sultana、Kiran Indukuri、Manash J. Deka、Anil K. Saikia
DOI:10.1021/jo4015547
日期:2013.12.6
(TMSOTf) can be efficiently used for Prins cyclization of acrylyl enol ethers to 5,6-dihydro-2H-pyran-2-acetates stereo- and regioselectively in good yields. The methodology was used for the totalsynthesis of natural product (+)-civet.
A highly efficient method for kineticresolution of racemic aliphatic alcohols without conversion of the hydroxyl group has been realized; the method involves hydrogenation mediated by a remote ester group and is catalyzed by a chiral iridium complex. This powerful, environmentally friendly method provides chiral δ-alkyl-δ-hydroxy esters and δ-alkyl-1,5-diols in good yields with high enantioselectivities