Palladium-Catalyzed Q‑Tube-Assisted Protocol for Synthesizing Diaza-dibenzo[a,e]azulene and Diaza-benzo[a]fluorene Derivatives via O2 Acid-Promoted Cross-Dehydrogenative Coupling

• Published in: Journal of organic chemistry 2020-12, Vol.85 (23), p.15368-15381
• Main Authors: Ibrahim, Hamada Mohamed, Behbehani, Haider
• Format: Article
• Language: English
• ISSN: 0022-3263; 1520-6904
• DOI: 10.1021/acs.joc.0c02186

An appropriate and efficient Q-tube-assisted palladium-catalyzed strategy for the synthesis of novel, unparalleled diaza-dibenzo­[a,e]­azulene and diaza-benzo­[a]­fluorene derivatives has been sophisticated, which includes oxygen and AcOH-induced oxidative C­(sp3)–C­(sp2) cross-dehydrogenative coupling reactions of 1-amino-2-imino-4-arylpyridine-3-carbonitriles with benzocyclic ketones such as benzosuberone, tetralone, thiochromone, and chromone, respectively. This Q-tube gas purging kit assisted-protocol features safe due to easy pressing and sealing, a wide substrate scope, easy workup and purifying phases, and the use of O2 as a benign oxidant, in addition to being scalable and having a high atom economy. The suggested mechanistic pathway includes a formal dehydrative step followed by palladium AcOH-induced CH(sp3)–CH(sp2) oxidative cross-coupling. In this study, X-ray crystallographic analysis has been used to authenticate the targeted products.