Palladium-Catalyzed ortho-Monoacylation of Arenes with Aldehydes­ via 1,2,4-Benzotriazine-Directed C–H Bond Activation

Abstract

An efficient palladium-catalyzed C–H bond functionalization/ortho-monoacylation reaction of 3-aryl-1,2,4-benzotriazines with (hetero)aryl or alkyl aldehydes has been developed, which offers a facile and alternative strategy for direct modification and further diversification of 3-aryl-1,2,4-benzotriazines. Bioactive 1,2,4-benzotriazine has been employed as a novel directing group for the palladium-catalyzed regioselective monoacylation of sp2 C–H bond protocol with broad substrate scope and good functional group tolerance.

Recent advances in the application of alkynes in multicomponent reactions

“…Jin and co-workers 55 synthesized 2,3-dihydro-1 H -imidazo[1,2- a ]indole derivatives 80 via the reaction among allylamine derivatives 79, sulfonyl azide derivatives 78, and alkyne derivatives 77 ( Scheme 35 ). In the first step, triethylamine (Et 3 N) as a base and CuI as a catalyst were added to the mixture in DMSO at room temperature for 1 h. After that, L1, K 2 CO 3 , and CuI were added to the mixture and heated at the temperature of 80 °C for 6 h.…”

Multicomponent cyclization with azides to synthesize N-heterocycles

“…In Liu's work, a coppercatalyzed multicomponent reaction involving sulfonyl azides, alkynes, and allylamines 127 was conducted to obtain 2,3dihydro-1H-imidazo-[1,2-a]indoles 128 in moderate yields. 88 In this reaction, the triazole intermediate is obtained and then decomposes into the ketenimine with the loss of nitrogen. This step is similar to the mechanism described in section 2.3.…”

Purinyl N-Directed Aroylation of 6-Arylpurine Ribo- and 2’-Deoxyribonucleosides, and Mechanistic Insights

“…46 The utility of aldehydes as p-acceptors in N-directed acylations requires a terminal oxidation, and whereas air was initially reported, 47 t-BuOOH has been a suitable oxidant in a variety of such acylation reactions. [48][49][50][51][52][53][54][55][56] Beyond aldehydes, other reagents have been utilized for N-directed aroylation reactions. 57 For example, acylations of 2-aryl pyridines have been conducted with aoxocarboxylic acids, 58 alcohols, 59 a-diketones, 60 toluene derivatives, 61,62 carboxylic acids, 63 benzyl amines, 64 styrenes, 65,66 phenyl acetylenes, 66,67 benzylic oxiranes, 67 mandelic acids, 68 benzylic halides, 69,70 and N-phenyl-N-tosylbenzamides.…”