Direct intramolecular double cross-dehydrogentive-coupling (CDC) cyclization of N-(2-pyridyl)amidines under metal-free conditions. Issue 72 (19th December 2019)

• Record Type: Journal Article
• Authors: Yi, Fengping; Fu, Chao; Sun, Qihui; Wei, Huazhen; Yu, Genfa; Yi, Weiyin
• Is Part Of: RSC advances. Volume 9:Issue 72(2019)
• Page Start: 42172
• Page End: 42182
• Publication Date: 2019-12-19
• Subjects: Chemistry -- Periodicals; 540.5
• DOI: 10.1039/c9ra09265j
• Languages: English
• ISSNs: 2046-2069

Abstract

Abstract : A metal-free protocol to form 2-iminoimidazo[1, 2- a ]-pyridines from N -(2-pyridyl)amidines, in which the constructed heterocyclic skeletons are promoted by CBr4 via radical or nucleophilic substitution reactions under mild conditions, is demonstrated. Abstract : A facile transition-metal-free protocol to form 2-iminoimidazo[1, 2- a ]-pyridines bearing a –CHBr2 group and an aza-quaternary carbon center at the 3 position from N -(2-pyridyl)amidines substrates, in which the new heterocyclic skeletons constructed from amidines via radical reactions or nucleophilic substitution reactions are promoted only by CBr4 under mild conditions, is demonstrated. The reactions were realized by intramolecular CDC reaction involving C–N and C–C bond formation via the sequential C(sp 3 )–H bifunctionalization mode on the same carbon atom under mild conditions. Moreover, this work also provides an excellent and representative example for CBr4 as an efficient reagent to initiate radical reactions under initiator-free conditions or to give rise to nucleophilic substitution reactions only by base.