Quinone methide Reaction with hydroxy compounds

Oxidative decarboxylation of 6-hydroxy-substituted TIQ-1-carboxylic acids to quinone methides under physiological conditions (pH 7 and above) was first reported by Bobbitt et al. (176,177). This reaction was later investigated in detail with dideoxynorlaudanosoline-1-carboxylic acid (92) (177). The yellow quinone methide 95, which was fully characterized, was converted by acid to the salt of DIQ 96 shown in Fig. 25. The spectral data collected for compounds 95 and 96 were in accord with this well-known interconversion of phenolic DIQs (I47a,I57). DIQ 96 on chemical reduction gave TIQ 97, and on acetylation it gave triacetate 98 with an exocyclic double bond (177). 

---