Abstract: The preparation and photolysis of simple cyclopentenones la-ld and 2 have been investigated. Two new photochemical reactions were found; these are the rearrangement of la-ld to cyclopropylketenes, isolated as esters 4 and 5, and closure of a 1, 4 biradical (l0) onto the double bond to form bicyclic ketones 8 and 9, In addition, examples of several other photochemical transformations were observed, leading to aldehydes 7 (a cleavage), ...
