RING TRANSFORMATIONS OF HETEROCYCLIC-COMPOUNDS .15. N-(2-HYDROXYPHENYL) SUBSTITUTED 2-ALKYLAMINO-4,6-DIARYLBENZOPHENONES BY RING TRANSFORMATION OF 2,4,6-TRIARYLPYRYLIUM SALTS WITH ANHYDROBASES OF BENZOXAZOLIUMSALTS
T. Zimmermann et al., RING TRANSFORMATIONS OF HETEROCYCLIC-COMPOUNDS .15. N-(2-HYDROXYPHENYL) SUBSTITUTED 2-ALKYLAMINO-4,6-DIARYLBENZOPHENONES BY RING TRANSFORMATION OF 2,4,6-TRIARYLPYRYLIUM SALTS WITH ANHYDROBASES OF BENZOXAZOLIUMSALTS, Journal of heterocyclic chemistry, 33(6), 1996, pp. 1679-1683
The synthesis of hitherto unknown N-(2-hydroxyphenyl) substituted 2-al
kylamino-4,6-diarylbenzophenones 3 from 2,4,6-triarylpyrylium salts 1
and 3-alkyl-2-methylbenzoxazolium salts 2 in the presence of triethyla
mine in ethanol by a 2,5-[C-4+C-2] pyrylium ring transformation is rep
orted. Structure elucidation is performed by an X-ray crystal structur
e determination of the benzophenone 3a. Spectroscopic data of the tran
sformation products and their mode of formation via anhydrobases of th
e salts 2 are discussed.