Versatile Synthesis of Cyclopropanecarboxylic Acid Derivatives by the Ni(CO)4-Induced Reductive Carbonylation Reaction of gem-Dibromocyclopropanes

Abstract
Reductive carbonylation of gem-dibromocyclopropanes was achieved by treatment with tetracarbonylnickel in the presence of alcohols, amines, thiols, or imidazole in DMF leading to the corresponding cyclopropanecarboxylic acid derivatives, respectively. Use of disulfides as an initial nucleophile resulted in carbonylation with sulfenylation at the geminal position. This method was applied to the intramolecular reductive carbonylation reaction of 2,2-dibromocyclopropanealkanols into bicyclic lactones. Nickel carbenoid and enolate complexes are assumed to be involved as key intermediates.