Photochemical cleavage of the cyclopropane ring of 6,20-epoxylathyrol {1,11-diacetoxy-3,6,6,14-tetramethyl-13-phenylacetoxy(tricyclo[10.3.0.0]pentadec-3-ene-10-spiro-2′-oxiran)-2-one}

Abstract

The products of direct and triplet-sensitized irradiation of 6,20-epoxylathyrol (1a) and the corresponding parent alcohol (1b) have been investigated. The major product of direct irradiation is a furan derivative, arising from cis-trans-isomerisation of the 11,12-double bond followed by cleavage at the cyclopropane ring and insertion of the resulting carbene into the carbonyl group. The nature of the electronic species involved in this reaction scheme is discussed.