Reaction of 5,5′-(1,4-Phenylene)bis(3-aryl-2-oxaspiro[5.5]undec-3-en-1-ones) with Methyl 1-Bromocyclohexanecarboxylate and Zinc

The reaction of 3,3'-(1,4-phenylene)bis(1-phenylprop-2-en-l-ones) with the Reformatsky reagent obtained from methyl 1-bromocyclohexanecarbovlate and zinc involves addition of two molecules of the reagent to the conjugated C=C-C=O systems of the substrate. The intermediate adducts undergo intramolecular cyclization via the nucleophilic attack of the enolate oxygen atoms on the carbonyl carbon atoms. The subsequent hydrolysis of the reaction mixture resulted in the isolation of bis(spiro-3,4-dihydropyran-2-ones). The structure of the products was confirmed by X-ray diffraction.