Benzotriazole-mediated 4-position derivatization of 2,6-diarylpyrylium cations by electrophiles
作者:Alan R. Katritzky、Weihong Du、Sergey N. Denisenko、Peter Czerney、Peter J. Steel
DOI:10.1002/(sici)1521-3897(199902)341:2<152::aid-prac152>3.0.co;2-y
日期:1999.2
2,6-Diaryl-4H-(benzotriazolyl)pyrans (7a-c) on treatment with n-butyllithium undergo smooth lithiation at the position a: to the benzotriazolyl moiety. In contrast to fused and bridged pyranyl derivatives, these pyranyl anions react with electrophiles by two routes: i) the expected electrophilic substitution resulting in various 4-alkyl- and 4-(omega-alkylfunctionalized)-pyrylium salts (12-19) or iii pyrylium ring rearrangement of 2,6-diarylpyrylium anions (8a-c), leading to 1,2-diaryl-3,1-cyclopentadien-1-ols (10a-c).