Et2NH/H2O catalyzed tandem aldol condensation - Diels-Alder cycloaddition sequence for the one-pot synthesis of (2R,3S)-rel-3-aryl-1,2,3,4,5,6,7,8-octahydro-6,6-dimethyl-8-oxo-2-naphthalenecarboxylates

Abstract

A tandem aldol condensation -Diels-Alder cycloaddition process is developed to combine isophorone (3,5,5-trimethyl-2-cyclohexen-1-one), aromatic aldehydes, and methyl acrylate in an efficient stereoselective one-pot synthesis of methyl (2R,3S)-rel-3-aryl-1,2,3,4,5,6,7,8-octahydro-6,6-dimethyl-8-oxo-2-naphthalenecarboxylates using trace quantities of ammonium ions under aqueous conditions. Alternatively, the respective conjugated dienes which are formed in situ from the condensation of isophorone with the aldehydes can also react with methyl acrylate in a stepwise fashion leading to the same products.