title: Synthesis of cyclic alkenylsiloxanes by semihydrogenation: a stereospecific route to (Z)-alkenyl polyenes.
abstract: Cyclic alkenylsiloxanes were synthesized by semihydrogenation of alkynylsilanes-a reaction previously plagued by poor stereoselectivity. The silanes, which can be synthesized on multigram scale, undergo Hiyama-Denmark coupling to give (Z)-alkenyl polyene motifs found in bioactive natural products. The ring size of the silane is crucial: five-membered cyclic siloxanes also couple under fluoride-free conditions, whilst their six-membered homologues do not, enabling orthogonality within this structural motif.
authors.affiliation: Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA, U.K. Fax: (+44) 1865-285002.
authors.forename: Bryony L
authors.initials: BL
authors.lastname: Elbert
authors.forename: Diane S W
authors.initials: DS
authors.lastname: Lim
authors.forename: Haraldur G
authors.initials: HG
authors.lastname: Gudmundsson
authors.forename: Jack A
authors.initials: JA
authors.lastname: O'Hanlon
authors.forename: Edward A
authors.initials: EA
authors.lastname: Anderson
keywords: alkynes; cross-coupling; hydrogenation; natural products; silanes