1,4-Addition to Tetracyclone. Kinetic vs. Thermodynamic Product Distribution

Article abstract of DOI:10.1021/jo00196a027

The Michael addition of cyanide ion to tetracyclone produces an enolate (4a) which, when protonated, affords a diastereomeric mixture of cis- (5a) and trans-4-cyano-2,3,4,5-tetraphenyl-2-cyclopenten-1-one (6a) in varying ratios depending upon the conditions employed.Quenching the enolate at low temperatures affords mainly the cis isomer, the kinetic product, while high temperature quench favors the trans isomer, the thermodynamic product.Base, acid and heat were used to interconvert the cis and the trans isomers into a thermodynamic equilibrium ratio of products.Protonation of the enolate (4b) of 4-methoxy-2,3,4,5-tetraphenyl-2-cyclopenten-1-one gave similar results.Methylation of both enolates 4a and 4b is also reported as well as the structure elucidation of the isomers obtained from the above reactions.