5-[2-(3-Ethylphenyl)ethyl]-2-methyloxazole-4-carboxylic acid → 7-Ethyl-9,10-dihydro-2-methyl-4H-benzo[5,6]cyclohepta[1,2-d]oxazol-4-one

Participants

Reaction Steps

A solution of the product from step (vii) (9.5 g) in thionyl chloride (100 ml) was stirred at room temperature for 4 days. After removal of solvent under reduced pressure, the residue was dissolved in 1,2-dichloroethane (200 ml) and treated with aluminium chloride (23 g). The reaction mixture was heated at reflux for 1 hour and allowed to cool. The resultant suspension was partitioned between 10% hydrochloric acid and dichloromethane. The combined extracts were evaporated, triturated with acetonitrile, and filtered through a plug of celite. Evaporation afforded a residue which was purified by chromatography eluting with 50-100% ethyl acetate in isohexane.

Provenance & Evidence