Cobalt Carbonyl Mediated Michael Addition: Direct Synthesis of Esters Containing Other Functional Groups from Activated Olefins

Article abstract of DOI:10.1021/jo00295a049

Hydrocarbalkoxylation of acrylonitrile with stoichiometric amounts of alcohols in the presence of catalytic amounts of Co2(CO)8 and pyridine bases leads to 2,4-dicyano-2-methylbutanoic acid esters.The yield of these Michael adducts shows a maximum as a function of the pyridine/cobalt ratio.Analogues reactions using equimolar amounts of alcohol, acrylonitrile, and an other activated olefin result in products with at least three different functional groups.Acrylonitrile with pyH gives (1-cyanoethyl)cobalt tetracarbonyl, which is proposed to be the key intermediate of the hydrocarbalkoxylation.This complex may be deprotonated to a "Michael donor" anion, i.e. the Michael adducts are most probably formed in a cobalt-mediated way.The above catalytic system promoted also the Michael addition of some C-H acids to activated olefins under atmospheric conditions.