The synthesis, reactivity, and applications of carbamate carbene complexes of chromium

n efficient synthesis of carbamate-substituted pentacarbonyl chromium carbene complexes was developed. These carbamate carbene complexes underwent efficient carbon monoxide insertion reactions upon photolysis in the presence of alcohols or amino esters to produce carbamate-protected ;Attempts to produce alkyl-substituted oxazolidinone carbene complexes led instead to an efficient and general synthesis of optically-active enecarbamates. In the course of investigating the scope and limitations of this new reaction, conjugate addition reactions into oxazolidinone(propenyl) carbene complexes and homo-Michael addition reactions into phthalimido(cyclopropyl) carbene complexes were discovered. Palladium(0) and Nickel(0)-catalyzed reactions between methyl acrylate and an oxazolidinone-substituted methylenecyclopropane produced by this method were investigated. Palladium catalysis in the presence of phosphine ligands produced both acyclic coupled products and dimers of the methylenecyclopropane. Nickel catalysis efficiently produced methylenecyclopentanes by the ring opening of the cyclopropyl substituent followed by a formal (3+2) cycloaddition with the acrylate, but asymmetric induction in the process was low.;An optically-active oxazolidinone-substituted chromium carbene complex was next synthesized. The photolysis of this complex in the presence of a variety of imines resulted in the production of...