PtCl₂-Catalyzed Cyclization of o-Diethynylbenzene Derivatives Triggered by Intramolecular Nucleophilic Attack

Abstract

PtCl₂-catalyzed cyclization of o-diethynylbenzene derivatives bearing a hydroxyethyl group yielded naphthofuran derivatives by initial intramolecular cyclization of the hydroxy group to an activated ethynyl group followed by attack of the second ethynyl group to a vinylplatinum intermediate. When the ethynyl terminal is substituted by a hydroxypropyl group, not only homologous naphthodihydropyran but also indenylidenetetrahydrofuran derivatives were formed.

Keywords:

• Cyclization
• dihydronaphthofuran
• Lewis acid
• nucleophilic addition
• o-diethynylbenzene

ACKNOWLEDGMENT

This work was supported by a Grant-in-Aid for Scientific Research from the Ministry of Education, Culture, Sports, Science, and Technology, Japan.