Polycyclic fused phenanthridines: An alternative approach from benzotriazoles
作者:Alan R. Katritzky、Weihong Du、Yasuhisa Matsukawa、Ion Ghiviriga、Sergey N. Denisenko
DOI:10.1002/jhet.5570360417
日期:1999.7
We describe an alternativeapproach to polycyclicphenanthridines (7) and some of their analogues using conditions much milder than those previously reported. The procedure includes the generation of a benzotriazole stabilized carbanion, oxidation of the resulting anion to a radical, and elimination of nitrogen followed by ring closure to produce phenanthridines.
A metal-free C(sp(3))-H/N-H cross-coupling of azoles with xanthenes and related activated arylmethylenes is presented. Both the use of azoles and the activation pattern of C(sp(3))-H sources are essential for this transformation. In the presence of 2.0 equiv of benzoyl peroxide (BPO), methylenes bearing a heteroatom-bridged bisaryl group reacted with various azolic N-H sources to afford C-N bond forming products in usually excellent or quantitative yields, and the diphenylmethane and methylenes coactivated by a phenyl group and an adjacent heteroatom are less reactive. Mechanistic investigations suggest that a radical/radical cross-coupling pathway might be involved.[GRAPHICS].
Syntheses of β,β-Diarylvinyl Phenyl Ketones by Benzotriazole-Mediated Tandem Coupling-Elimination
作者:Alan R. Katritzky、Sergey N. Denisenko、Daniela C. Oniciu、Ion Ghiviriga