Reactivity Patterns in the Rhodium Carbenoid Induced Tandem Cyclization-Cycloaddition Reaction

Article abstract of DOI:10.1021/jo00265a019

The rhodium(II) acetate catalyzed behavior of ο-<(propenyloxy)methyl>-α-diazoacetophenone was studied.The results obtained are consistent with a mechanism in which the key step involves intramolecular cyclization of the ketocarbenoid onto the oxygen atom of the side chain to give an oxonium ylide intermediate which undergoes either C-H insertion or a competitive 2,3-sigmatropic rearrangement.The reaction of 1-diazo-9-decene-2,5-dione with rhodium(II) acetate results in cyclization of the intermediate rhodium carbenoid to give a six-ring carbonyl ylide which readily undergoes intramolecular dipolar cycloaddition.This reaction does not occur when the keto group of the diazo compound has been replaced by an ester functionality.Similar results were also obtained with cis-2-benzoyl-1-(diazoacetyl)cyclopentane.