Synthesis of C-5′-alkyl substituted 17-spirofuran 19-norsteroids
摘要:
A number of new steroidal 17-spirofuran derivatives of the 19-nor series containing Me, Et or Pr-i-substituents in the heterocyclic moiety has been prepared, which are expected to have a strong progestagenic activity. The proposed approach made use of the 1,3-dipolar cycloaddition of low-molecular nitrile oxides with steroidal acetylenic alcohols followed by transformation of the isoxazole side chain. (C) 2001 Elsevier Science Inc. All rights reserved.
1,3-Dipolar cycloadditions of prop-1-ene-1,3-sultone with nitrile oxides/nitrones
作者:H. Zhang、W.H. Chan、Albert W.M. Lee、W.Y. Wong
DOI:10.1016/s0040-4039(02)02502-9
日期:2003.1
scope and limitations of dipolar cycloaddition reactions between nitrile oxides/nitrones and prop-1-ene-1,3-sultone have been investigated. A remarkably high degree of regioselectivity and stereoselectivity was observed. The homochiral sultam 8e was synthesized in a four-step reaction sequence starting from the substituted isoxazoline 4e obtained from the cycloaddition. The absolute stereochemistry of
Diastereoselective [3+2] cycloadditions of a camphor-derived chiral N-acryloylhydrazide with nitrile oxides: the preparation of optically pure Δ2-isoxazolines
Reaction of a novel chiral N-acryloylhydrazide with various nitrile oxides proceeded smoothly to afford the cycloadduct with high diastereoselectivity (99:1). The auxiliary can be easily removed from the cycloadducts under mild conditions.
Novel C-2 Substituted Carbapenem Derivatives. Part II. Synthesis and Structure-activity Relationships of Isoxazolin-2-yl, Isoxazolidin-2-yl and 2-Pyrazolin-2-yl Carbapenems Generated Using 1,3-Dipolar Cycloaddition Chemistry.
作者:GEORGE BURTON、GRAHAM J. CLARKE、JAMES D. DOUGLAS、A. JOHN EGLINGTON、COLIN H. FRYDRYCH、JEREMY D. MINKS、NICHOLAS W. HIRD、ERIC HUNT、STEPHEN F. MOSS、ANTOINETTE NAYLOR、NEVILLE H. NICHOLSON、MICHAEL J. PEARSON
DOI:10.7164/antibiotics.49.1266
日期:——
A series of carbapenems containing novel C-2 semisaturated heterocyclic substituents were synthesised by 1,3dipolarcycloaddition reactions of nitrile oxides, nitrile imines and a nitrone to 2-vinylcarbapenem. The isoxazoline and isoxazolidine compounds showed potent antibacterial activity but moderate stability to human dehydropeptidase 1 (DHP-1). Stability to DHP-1 was improved by methyl substitution