An enantioselectivesynthesis of a putativelipiarmycinaglycon was accomplished and features: 1) Brown′s enantioselective alkoxyallylboration and allylation of aldehydes, 2) chain elongation by iterative Horner–Wadsworth–Emmons olefination, 3) Evans’ aldol reaction and 4) an ene‐diene ring‐closing metathesis. A neighboring‐group‐assisted chemoselective reductive desilylation was uncovered in this
Pd-Catalyzed Asymmetric Intermolecular Hydroalkoxylation of Allene: An Entry to Cyclic Acetals with Activating Group-Free and Flexible Anomeric Control
作者:Wontaeck Lim、Jungjoon Kim、Young Ho Rhee
DOI:10.1021/ja508587f
日期:2014.10.1
A ligand-directed metal-catalyzed asymmetric intermolecular hydroalkoxylation of alkoxyallene is reported. Combined with ring-closing-metathesis, this reaction offers a new atom-efficient synthetic method toward various cyclic acetals with elaborate anomeric control. Synthetic utility of the reaction was demonstrated by the atom-efficient and stereodivergent access to various mono- and disaccharides.
Stereoselective synthesis of the C7C21 segment of epothilone A via asymmetric alkoxyallyl- and crotylboration
The synthesis of the C-7-C-21 fragment of epothilone A involving asymmetric alkoxyallyl- and crotylboration using alpha-pinene-derived reagents is described. (C) 2003 Elsevier Science Ltd. All rights reserved.