Synthesis of 2-alkyl-substituted isoflavonoid analogues with non-aromatic ring A on the basis of 2-[2-(aryl)acetyl]cyclohexane-1,3-diones and carboxylic acid anhydrides

A simple and convenient method for the synthesis of 2-alkyl-substituted analogues of isoflavonoids with nonaromatic ring A is proposed. The method consists of acylation of 2-[2-(aryl)acetyl]cyclohexane-1,3-diones with carboxylic acid anhydrides followed by intramolecular aldol-crotonic condensation of the resulting enolacylates in the presence of basic agents (triethylamine, sodium acetate, potassium carbonate). 2-[2-(Aryl)acetyl]cyclohexane-1,3-diones were obtained by condensation of 5-substituted cyclohexane-1,3-diones with arylacetic acids under the action of dicyclohexylcarbodiimide and 4-(dimethylamino)pyridine-catalyzed O-C isomerization of the resulting O-acylates.