The Chemistry of Phthalidecarboxylic Acid. IV. Michael Additions to Conjugated Ketones

Abstract

Michael additions of methyl 3-oxo-1,3-dihydroisobenzofuran-1-carboxylate to conjugated ketones are reported. The use of amine catalysts gives only the kinetic product; the use of cinchonine and cinchonidine gives a single diastereoisomer with 67% enantiomeric excess and of opposite chirality respectively. The use of lithium diisopropylamide gives 4-oxotetrahydronaphthalenes which react with aqueous base to give the thermodynamic diastereoisomer of the Michael adduct.