Studies on the syntheses of heterocyclic compounds. part CCLXXIX . Synthesis of O-isobutylcularidine

Although various methods of oxepine formation from phenoxybenzene dicarboxylic acids was attempted, only 11-hydroxy-4-isobutoxy-7,8-dimethoxydibenz[b,f]oxepin-l-ylaeetic acid lactone (XXX) was synthesized successfully. Compound XXX gave O-isobutylcularidine (XXXVlIb) in a few steps. Our synthetic O-isobutylcularidine was identical with that prepared from natural cularidine proving the structure for cularidine proposed by Manske. However, dealkylation of synthetic O-isobutylcularidine was unsuccessful.