Homogeneous mixed-metal catalyst systems: new and effective routes to N-acyl-α-amino acids via carbonylations

New homogeneous mixed metal catalyst systems for the synthesis of N-acyl-α-amino acids directly from allylic alcohols, oxiranes or olefins are described. The new catalytic processes include (a) the isomerization-amido-carbonylation of allylic alcohols catalyzed by Co₂(CO)₈-Group VIII transition metal complex combinations, (b) the isomerization-amido-carbonylation of oxiranes promoted by Co₂(CO)₈-Lewis acid systems, and (c) the hydroformylation-amidocarbonylation of fluoro-olefins catalyzed by Co₂(CO)₈-rhodium carbonyl systems which proceeds with excellent regio-selectivity. It is found that the hydroformylation-amidocarbonylation process includes a unique Co-Rh mixed metal cluster, CoRh(CO)₇, as an active catalyst species. The mechanism of this novel mixed cluster-catalyzed process is discussed. Possible mechanisms for the isomerization-amidocarbonylations are also proposed.