Pinacol rearrangement for constructing asymmetric centers adjacent to heterocycles
摘要:
Stereospecific pinacol-type 1,2-shift of electron-rich heterocycles was achieved Under organoaluminum-promoted conditions to afford optically pure ketones or alcohols possessing these heterocycles. The method was applied to the asymmetric formal total synthesis of indolmycin. (C) 2002 Elsevier Science Ltd. All rights reserved.
Reductive pinacol-typerearrangement of chiral α-mesyloxy ketones was effected by organoaluminums (DIBAL in combination with Et3Al or Et2AlCl) leading to enantiomerically pure 2-aryl- or 2-alkenyl-1-propanols.
Two chiral intermediates, C(1)–C(9) and C(11)–C(17) portionsof protomycinolide IV, were synthesized both from (S)-ethyl lactatevia asymmetric pinacol-type rearrangement followed bydiastereoselective reactions on α-methyl-β,γ-unsaturatedcarbonyl compounds.
Stereoselective Syntheses of (+)-Davanone and (+)-Artemone via Anti-selective Epoxidation and Iodo-cyclization
作者:Yutaka Honda、Aiichiro Ori、Gen-ichi Tsuchihashi
DOI:10.1246/cl.1987.1259
日期:1987.7.5
Chiral sesquiterpenes, (+)-Davanone and (+)-Artemone, were synthesized via anti-selective epoxidation and iodo-cyclization by the use of (S)-ethyl lactate as a chiral source.
Fluoride ion-catalyzed reduction of aldehydes and ketones with hydrosilanes. Synthetic and mechanistic aspects and an application to the threo-directed reduction of .alpha.-substituted alkanones