Synlett 2006(4): 0575-0578  
DOI: 10.1055/s-2006-932482
LETTER
© Georg Thieme Verlag Stuttgart · New York

A Direct Entry to Bicyclic Cyclobutenes via Platinum-Catalyzed ­Cycloisomerization of Allenynes

Takanori Matsuda, Sho Kadowaki, Tsuyoshi Goya, Masahiro Murakami*
Department of Synthetic Chemistry and Biological Chemistry, Kyoto University, Katsura, Kyoto 615-8510, Japan
Fax: +81(75)3832748; e-Mail: murakami@sbchem.kyoto-u.ac.jp;
Further Information

Publication History

Received 29 November 2005
Publication Date:
20 February 2006 (online)

Abstract

Allenynes underwent cycloisomerization in the presence of a catalytic amount of platinum(II) chloride at 80 °C to give ­bicyclic cyclobutenes. A mechanism involving non-classical ­carbocationic intermediates was proposed for the formation of ­cyclobutenes.

7

CO accelerates the PtCl2-catalyzed cycloisomerization of enynes (ref. 3a). However, no accelerating effect of CO was observed in the present allenyne cycloisomerization.

8

Other PtCl2 complexes bearing additional ligands, such as PtCl2(cod) and PtCl2(PPh3)2, failed to exhibit any catalytic activity.

9

This abstraction process (BF) could proceed either inter- or intramolecularly.