Synthesis of Tribenzo[b,d,f]azepines via Cascade π-Extended Decarboxylative Annulation Involving Cyclic Diaryliodonium Salts

Abstract

Various functionalized tribenzo­[b,d,f]­azepines were prepared efficiently with the readily available 2-aminobenzoic acids and cyclic hypervalent diaryliodonium reagents as starting materials under Pd­(II) catalysis. The key of this step-economical protocol is that the carboxylic acid functionality was employed as both a traceless directing group for the N–H activation/arylation and a functional handle for the tandem π-extended decarboxylative annulation.

Diaryliodoniums Salts as Coupling Partners for Transition-Metal Catalyzed C- and N-Arylation of Heteroarenes

“…Even if tandem reactions including various sequences combining oxidation reactions or nucleophilic additions are widespread [130], tandem catalytic couplings on heteroarenes are really sparse and still remain a great challenge. Although decarboxylative cross-coupling reactions are not covered in this review, it is worth mentioning two recent reports from the group of Zhang who reported the tandem π-extended decarboxylative annulation [131,132]. Significant achievements have been reported by Greaney in the last 5 years, who was the first to describe tandem N-/N-, C-/N-and N-/C-arylation starting from unprotected heteroarenes and acyclic diaryliodoniums [133].…”

Tandem cyclization/arylation of diaryliodoniums via in situ constructed benzoxazole as a directing group for atom-economical transformation

“…Greaney and co-workers have designed excellent reaction patterns using nitrogen-containing heterocycles including indole, pyrazole and triazole to achieve dual arylation. 6,7 Of note, these heterocycles are employed as nucleophiles for the first arylation to form C–N bonds and subsequently as C–H activation groups to complete the second arylation (Scheme 1b). 7…”

Palladium-Catalyzed Dual Coupling Reaction of 2-Iodobiphenyls with o-Bromoanilines through C–H Activation: An Approach for the Synthesis of Tribenzo[b,d,f]azepines

“…Some tribenzo­[ b , d , f ]­azepine derivatives exhibit novel pharmacological properties . Furthermore, 9 H -tribenzo­[ b , d , f ]­azepines are also essential intermediates in the synthesis of the functional materials and bioactive molecules. , However, synthetic methods for tribenzo­[ b , d , f ]­azepines are rare and should be developed …”