Generation and intramolecular cyclization of α-sulfinyl and α-sulfonyl radicals
摘要:
alpha-Phenylsulfinyl and alpha-Phenylsulfonyl radicals are generated by the reactions of alpha-chlorosulfoxides and alpha-chlorosulfones with tributyltin hydride, respectively. High reaction concentration (0.2 M) is required to ensure efficient generations of these radicals. The 5-exo-type intramolecular cyclizations of these radicals are studied. The cyclization is most successful when the olefin is terminally substituted with an ester group. The sulfinyl group only induces mild diastereoselectivity on the cyclization. (C) 1997 Elsevier Science Ltd.
Chromium(III) catalyzed synthesis of allenes from propargyl derivatives via a carbometalation–elimination sequence
作者:Gary A. Molander、Erin M. Sommers
DOI:10.1016/j.tetlet.2005.01.143
日期:2005.3
The syn-carbometalation/syn-elimination of propargyl substrates to form allenes has been achieved using cationic chromium(III) catalysts activated by alkylaluminums. The mechanism and scope of this transformation are presented. (c) 2005 Elsevier Ltd. All rights reserved.