Fig. 1. (a) Carboxyl radical-induced dearomative spirolactonization of biaryl carboxylic acids. PC denotes a photocatalyst, and PO denotes a photooxidant. Potential transformations of the highly functionalized motif. (b) Previous reports regarding transformations of biaryl carboxylic acids, where ipso-substitution of the methoxy group was observed. (c) Examples of relevant compounds containing a spirolactone or dearomatized biaryl functionality.14–16 .
