title: Stereoselective synthesis of syn-configured alpha-allenols by rhodium-catalyzed reaction of alkynyl oxiranes with arylboronic acids.
abstract: A rhodium-catalyzed reaction of alkynyl oxiranes with arylboronic acids affords syn-configured alpha-allenols with high diastereoselectivity. The reaction is initiated by addition of an arylrhodium(I) species onto the alkyne moiety of the alkynyl oxirane. The resulting alkenylrhodium(I) intermediate undergoes beta-oxygen elimination to open the oxirane ring in a syn-selective fashion. Protonolysis of the rhodium(I) alkoxide with arylboronic acid releases the corresponding alpha-allenol along with the rhodium(I) boronate, which undergoes beta-aryl elimination to regenerate the arylrhodium(I) species. The utility of this method is demonstrated by an application to a concise synthesis of (+/-)-Boivinianin B.
authors.affiliation: Department of Synthetic Chemistry and Biological Chemistry, Kyoto University, Katsura, Kyoto 615-8510, Japan.
authors.forename: Tomoya
authors.initials: T
authors.lastname: Miura
authors.forename: Masahiko
authors.initials: M
authors.lastname: Shimada
authors.forename: Paula
authors.initials: P
authors.lastname: de Mendoza
authors.forename: Carl
authors.initials: C
authors.lastname: Deutsch
authors.forename: Norbert
authors.initials: N
authors.lastname: Krause
authors.forename: Masahiro
authors.initials: M
authors.lastname: Murakami