Dimerization–cyclization reactions of isocyanoaryl-tethered alkylidenecyclobutanes via a triplet biradical mediated process

Abstract

A triplet biradical mediated dimerization-cyclization reaction of isocyanoaryl-tethered alkylidenecyclobutanes has been reported in this paper, giving a new protocol for the construction of macrocyclic skeleton including dihydroquinoline and quinoline units...

De Novo Synthesis of 2,2′-Bipyridines and Related Bis-azines via Cascade Coupling and Double Pyridannulation of Isocyanides

“…A good yield was restored when performing the reaction on a 10 mmol scale, and 1.18 g of 2a was isolated (Scheme ). In line with literature precedent − and our previous studies, , the mechanism involves the formation of a key 1,4-diazabutatriene intermediate I , which engages in “head-to-head” coupling of the terminal carbon atom of isocyanide 1a , and then I undergoes spontaneous 6π-electrocyclization/aromatization to furnish the 3,3′-diphenyl 2,2′-bipyridiyl 2a .…”

“…The dimerization of two isocyanides was first reported in 1977 by Höfle and Lange for the synthesis of 4,4′-bis-quinazoline as a serendipitous result (1 example in 32% yield) . After that, 2,2′-biquinolines, fused imidazo­[1,2- a ]­pyridines, 2-(isoquinolin-1-yl)­oxazoles, and benzo­[ b ]­[1,4]­oxazin-2-ones have been accordingly prepared by utilizing this reaction. In 2016, we documented the first heterodimerization of two different isocyanides that enables the synthesis of pyrrolo­[3,4- b ]­indoles .…”