Studies of chromens. Part 2. Synthesis of 7-methoxy-2,2-dimethylchromen-3-carboxylic acid

Abstract

The preparation of the title compound (1a) is described. Effects of C-2 methyl groups on ring opening and alkylation of chroman-4-ones under basic conditions are discussed. The reaction of hydrazine with 3-ethoxycarbonyl-7-methoxy-2,2-dimethylchromen (1d) and 3-ethoxycarbonyl-7-methoxy-2,2-dimethylchroman-4-one (3f) failed to give the pyrazolidinone or pyrazolinone.