A Novel Redox Reaction between 8-Aza-5,7-dimethyl-2-trifluoromethylchromone and Alkyl Mercaptoacetates. Facile Synthesis of CF3-Containing 2-Pyridone Derivatives

8-Aza-5,7-dimethyl-2-trifluoromethylchromone reacts with alkyl mercaptoacetates in the presence of triethylamine to give pyrido derivatives of 2-oxa-7-thiabicyclo[3.2.1]octane, which undergo the reductive ring opening to alkyl 2-[[3-(4,6-dimethyl-2-oxo-1,2-dihydropyridin-3-yl)-3-oxo-1-(trifluoromethyl)propyl]sulfanyl]acetates. The latter can be also obtained directly from 8-aza-5,7-dimethyl-2-trifluoromethylchromone and behave as the masked alpha,beta-unsaturated ketone, 4,6-dimethyl-3-(4,4,4-trifluorobut-2-enoyl)pyridin-2(1H)-one. This compound was independently synthesized from 3-acetyl-4,6-dimethyl-2-pyridone, and its synthetic potential was studied. A wide variety of 2-pyridone derivatives containing the CF(3) group have been prepared in good to moderate yields.