LETTER	Synlett 2006: 2941-2946   DOI: 10.1055/s-2006-949625
© Georg Thieme Verlag Stuttgart · New York
Palladium-Catalyzed Heck Alkynylation of Benzyl Chlorides
Catharine H. Larsen, Kevin W. Anderson, Rachel E. Tundel, Stephen L. Buchwald*
Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA Fax: +1(617)2533297; e-Mail: sbuchwal@mit.edu;
Received 17 April 2006

Abstract

An efficient and general protocol for the palladium-catalyzed Heck alkynylation of benzyl chlorides was developed. A ­catalyst system comprised of PdCl₂(CH₃CN)₂ and 2-dicyclohexyl­phosphino-2′,4′,6′-triisopropylbiphenyl (XPhos), with Cs₂CO₃ as the base, efficiently couples a wide range of functionalized terminal alkynes and substituted benzyl chlorides at 65 °C. We have also demonstrated that the corresponding aryl allene product can be ­selected for using an excess amount of base and higher reaction temperatures (80 °C) in a one-pot procedure.

Key words

palladium - alkynes - Heck alkynylation - benzyl chlorides - allene