A pathway of aromatic compound degradation by ortho-cleavage; one branch converts protocatechuate, derived from phenolic compounds, to beta-ketoadipate, and the other branch converts catechol, generated from various aromatic hydrocarbons, amino aromatics, and lignin monomers, also to beta-ketoadipate. Two additional steps accomplish the conversion of beta-ketoadipate to tricarboxylic acid cycle intermediates.