Manganese‐Catalyzed Direct Olefination of Methyl‐Substituted Heteroarenes with Primary Alcohols

Abstract

Herein, we present the first catalytic direct olefination of methyl-substituted heteroarenes with primary alcohols through an acceptorless dehydrogenative coupling. The reaction is catalyzed by a complex of the earth-abundant transition metal manganese that is stabilized by a bench-stable NNN pincer ligand derived from 2-hydrazinylpyridine. The reaction is environmentally benign, producing only hydrogen and water as byproducts. A large number of E-disubstituted olefins were selectively obtained with high efficiency.

Phosphine Ligand‐Free Ruthenium Complexes as Efficient Catalysts for the Synthesis of Quinolines and Pyridines by Acceptorless Dehydrogenative Coupling Reactions

“…[29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][60][61][62][63] Metal-ligand cooperative catalysis [64][65][66][67] can dramatically improve catalytic performance of ADC reactions using pincer ligands bearing NH, OH or CH 2 functionality. [40][41][42][43][44][68][69][70][71][72][73][74][75][76][77][78][79][80][81] Milstein, [40] Sun, [41] Yu, [42] Kundu [43] and Chen [44] have independently developed bifunctional Ru(II) catalysts for the synthesis of pyridine and quinoline derivatives (Scheme 1), but these catalysts were often air/water sensitive, involved a somewhat complicated synthesis, or required to...…”

Manganese Catalyzed Acceptorless Dehydrogenative Coupling Reactions

“…While Kempe and co‐workers approached the reaction with the PNP−Mn complex Mn‐22 (Scheme a), Maji et al. used an in situ generated NNN‐pincer stabilized complex Mn‐23 for the ADC of N ‐heteroarenes 12 with 1 (Scheme b) . In both cases, it was found that the reaction was highly selective and gave only Z‐isomer of the olefination product 13 .…”

Manganese‐Catalyzed C−H Olefination Reactions

“…Diverse reactions of hydrogenation, dehydrogenation and others have been successfully achieved . Recently, Maji and coworkers described a manganese pincer complex catalyzed olefination reaction of methyl‐substituted heteroarenes with primary alcohols (Scheme ) . An NNN pincer ligand derived from 2‐hydrazinylpyridine was shown to be essential to this transformation.…”

“…[30] Recently, Maji and coworkers described a manganese pincer complex catalyzed olefination reaction of methyl-substituted heteroarenes with primary alcohols (Scheme 11). [31] An NNN pincer ligand derived from 2-hydrazinylpyridine was shown to be essential to this transformation. A variety of disubstituted olefins were synthesized with exclusive E-configuration, which find extensive applications in pharmaceuticals, agrochemicals and synthetic intermediates.…”