Studies on pyrazines. 36. A novel synthesis of 6‐(2‐hydroxyethyl)‐1,3‐dimethyllumazine

The titled compound was synthesized by cycloaddition of 5,6,7,8‐tetrahydro‐5,7‐dimethyl‐3,6,8‐trioxo‐3H‐pyrimido[5,4‐c][1,2,5]oxadiazine ( 1 ) with 2,3‐dihydrofuran ( 2a ).     

Condensation of methylhydrazine with 4‐ethoxy‐1,1,1‐trifluoro‐3‐buten‐2‐one. A reinvestigation

In contrast to previous reports, 4‐ethoxy‐1,1,1‐trifluoro‐3‐buten‐2‐one ( 1 ) was observed to react with methylhydrazine ( 2 ) in refluxing ethanol to yield 1‐methyl‐3‐(trifluoromethyl)pyrazole ( 6 ) and 4,5‐dihydro‐1‐methyl‐5‐(trifluoromethyl)pyrazol‐5‐ol ( 4 ). The later compound undergoes acid catalyzed dehydration to 1‐methyl‐5‐(trifluoromethyl)pyrazole ( 3 ).