High Selectivity in the Oxidation of Mandelic Acid Derivatives and in O-Methylation of Protocatechualdehyde: New Processes for Synthesis of Vanillin, iso-Vanillin, and Heliotropin

New synthetic procedures for vanillin, iso-vanillin, heliotropin, and protocatechualdehyde starting from catechol are described. The utilisation of statistical experimental design and multivariate modelling and the mechanistic interpretation of the acid and base catalysis in the condensation of catechol derivatives with glyoxylic acid and in the regiocontrolled methylation of protocatechualdehyde and of the Cu(II) salt catalysis in the oxidative decarboxylation of mandelic acid derivatives have allowed the development of new highly selective processes.