Functionalization of Aromatic N-Heterocycles via C(sp2)–H/C(sp2)–H CDC Reactions

Heptafluorobutyric Acid Catalyzed Cross-Dehydrogenative Coupling of 7-Aminocoumarins with 1,2,4-Triazines: A Straightforward Pathway to 3-Triazinyl-7-aminocoumarins

“…In the same manner, the reaction with 3-(thiophen-2-yl)triazine ( 2r ) produced the corresponding cross-coupling product 3r in moderate yield. In addition, we found that electron-deficient heterocyclic substituents such as pyridine, pyrimidine, and pyrazine, which are capable to interact with π-excessive (het)arenes, 29 30 could also be tolerated in this transformation and the CDC products 3s – u were obtained in high yields without the formation of any by-products. We also carried out large-scale synthesis of compound 3a (2 mmol) and 0.55 g (81%) of compound 3a was obtained.…”

Direct CH/CH functionalization of 1,3-dihydroxy-9H-xanthen-9-one and 1,3-dimethoxy-9H-xanthen-9-one with 1,2,4-triazines and quinazoline

“…Reactions of nucleophilic substitution of hydrogen (S N H ) in a series of π-deficient heterocycles are one of the types of crossdehydrogenation coupling (CDC) and proceed as the addition of a nucleophile to an electrophile with the formation of the so-called σ H -adduct, which can subsequently be oxidized to a product with a completely aromatic structure (Scheme 1). This direction makes it possible to abandon the preliminary functionalization of the initial reagents and to reduce the amount of side reagents-waste [2].…”