Trifluoromethyl dihydroquinazolines

Diazadienes 314 (R2 = Ph) afforded, in the same way, good yields of bis-trifluoromethyl dihydroquinazolines 335, as reported by Burger and Penninger (Scheme 74). However, N-unsubstituted heterodienes 314 (R2 = H) yielded upon heating with aromatic nitriles symmetrical triazine derivatives 336 through a [4 + 2] cycloaddition (78S524). Muchowski and co-workers have employed the related 2-trichloromethyl-4-dimethyl-amino-1,3-diaza-l, 3-butadienes 337 for synthesizing 2-trichloromethylpyr-imidines 338 in 38-98% yield by cyclization with electron-deficient acetylenes moreover, triazine 339 was obtained in 80% yield in the reaction of... 

Base-initiated cyclization has also been achieved with trifluoromethyl amidines 792 where ring closure to 3,4-dihydroquinazoline-4-carboxylates 793 was accompanied by loss of fluorine <2000CC1883>. 

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