Synthesis of 6-Cyano-2,2-dimethyl-2H-1-benzopyran and Other Substituted 2,2-dimethyl-2H-1-benzopyrans

Article abstract of DOI:10.1021/jo00116a025

A practical synthesis of 6-cyano-2,2-dimethyl-2H-1-benzopyran (1) has been developed.This process involves the pyridine-catalyzed condensation of 1,1-diethoxy-3-methyl-2-butene (6) with 4-cyanophenol (3) in toluene or xylene at elevated temperatures.The development of this process, including an evaluation of solvents, bases, acid catalysts, and alterantive acetals, along with an improved synthesis of 1,1-diethoxy-3-methyl-2-butene, is discussed.Using this method, a variety of other substituted 2,2-dimethyl-2H-1-benzopyrans were synthesized.