The synthesis of mycophenolic acid from 2,4-dihydroxybenzoic acid

Mycophenolic acid is generated when 2,4-dihydroxybenzoic acid suffers three essential substitutions regioselectively. A fast, uncatalyzed substitution of the bromide by methyllithium at low temperature leads to incorporation of the methyl substituent at site 5 of the 2,4-dihydroxybenzoic acid. Many intermediates come from these reactions, in a process suited to lab use with few chromatographic separations.