B-Alkylcatecholboranes, easily prepared in situ by hydroboration of alkenes, are powerful radical precursors that can be used for carbon-carbon bond formation. Typical procedures for (a) conjugate addition to enones, (b) conjugate addition to activated alkenes such as vinyl sulfones, and (c) direct allylation are described. Experimentally, these three one-pot reactions are easy to perform. No slow
One-Pot Rhodium(I)-Catalyzed Hydroboration of Alkenes: Radical Conjugate Addition
作者:Philippe Renaud、Cyril Ollivier、Valéry Weber
DOI:10.1021/jo034515v
日期:2003.7.1
B-Alkylcatecholboranes, prepared by rhodium(I)-catalyzed hydroboration of alkenes, are suitable radical precursors for conjugate addition to activated olefins. This procedure proved to be particularly useful for the control of the regio- and chemoselectivity of such tandem processes. Enantioselective hydroboration has also been successfully coupled with radical chain reaction in a one-pot process.
Self-terminating, oxidative radical cyclizations of medium-sized cycloalkynones with inorganic and organic oxygen-centered radicals of type XO˙: the reaction pathway depends on the nature of X
作者:Uta Wille、Christian Jargstorff
DOI:10.1039/b201672a
日期:2002.4.9
The reaction of various inorganic and organic oxygen-centered radicals of type XO˙ with cyclodec-5-ynone 6 can be used as a mechanistic probe to study the ease with which X˙ acts as a leaving group in self-terminating, oxidative radical cyclizations. It was observed that when X˙ has good leaving ability the reaction leads to formation of the bicyclic epoxy ketones 13 and 14, whereas in the other cases