Cyclisation of Stobbe Condensation Products

Department of Chemistry, Institute of Science, Nagpur-440 001

Manuscript received 10 April 1990, revised 10 October 1990, accepted 14 January 1991

STOBBE condensation of benzhydrilidenesuccinatea with ketones gave methyl 2-benzhydrilidene-3-carboxy-3-alkylidene butenoate which on saponi­fication yielded 2-benzhydrilidene-3-carboxy-3-alkyli­dene butenoic acids (2e--h). In general, E-s-trans-structure,.was fixed for these acidsl. However, a free rotation is possible at C-C single bond between two double bonds giving possibility of s-cis-orientation too. Based on these concepts, molecular structures are fixed for the products obtained by cyclisation reactions with their anhydrides.