PAPER	Synthesis 2006: 2139-2142   DOI: 10.1055/s-2006-942420
© Georg Thieme Verlag Stuttgart · New York
Cyclizations of α-Diketones to α-Hydroxycyclopentenones on Silica Gel in the Absence of Solvent
Elizabeth A. Uhricha, William A. Batsona, Marcus A. Tius*a,b
a 2545 The Mall, University of Hawaii, Honolulu, HI 96822, USA b The Cancer Research Center of Hawaii, 1236 Lauhala Street, Honolulu, HI 96813, USA Fax: +1(808)9565908; e-Mail: tius@gold.chem.hawaii.edu;
Received 29 April 2006

Abstract

Stirring α,β-unsaturated α-diketones in the presence of activated silica gel results in cyclization to α-hydroxycyclopentenones in good yield. The reaction is sensitive to the mode of stirring and proceeds more rapidly in the presence of triethylamine. This is consistent with a Nazarov reaction proceeding through the enol tautomer of the α-diketone.

Key words

diketones - cyclizations - Nazarov reactions - silica gel - rearrangements