A facile, one-pot synthesis of Ephedra-based aziridines
作者:Jonathan A. Groeper、Joel B. Eagles、Shawn R. Hitchcock
DOI:10.1016/j.tetasy.2009.07.016
日期:2009.9
A series of enantiomerically and diastereomerically enriched N-sulfonylaziridines have been prepared by a single-pot process from (1R,2S)- and (1S,2R)-norephedrine and (1S,2S)-pseudonorephedrine. The cyclization process involved N-sulfonylation of the Ephedra alkaloid followed by O-sulfonylation with methanesulfonyl chloride. The bis(sulfonyl) Ephedra derivatives were treated with either hydrazine or sodium hydroxide to afford the N-sulfonylaziridines. (C) 2009 Elsevier Ltd. All rights reserved.
Enantioselective synthesis of optically active homoallylamines by nucleophilic addition of chirally modified allylboranes to N-silylimines
Enantioselectivity in the allylboration of N-silylimines with a variety of chirallymodifiedallylboronreagents has been examined. Optically active N-sulfonylamino alcohols (16, 17 and 19) derived from D-camphor and norephedrine were found to be efficient chiral ligands for the allylboration reagent. These reagents smoothly reacted with N-silylimines to give the corresponding homoallylic amines in
catalyst for enantioselective aminations of silyl enol ethers derived from acyclic ketones or alpha,beta-enones with [N-(2-nitrophenylsulfonyl)imino]phenyliodinane (NsN=IPh), providing N-(2-nitrophenylsulfonyl)-alpha-amino ketones in high yields and with enantioselectivities of up to 95% ee. The effectiveness of the present catalytic protocol has been demonstrated by an asymmetric formal synthesis of (-)-metazocine