Diboron-Catalyzed Dehydrative Amidation of Aromatic Carboxylic Acids with Amines

Abstract

Tetrakis(dimethylamido)diboron and tetrahydroxydiboron are herein reported as new catalysts for the synthesis of aryl amides by catalytic condensation of aromatic carboxylic acids with amines. The developed protocol is both simple and highly efficient over a broad range of substrates. This method thus represents an attractive approach for the use of diboron catalysts in the synthesis of amides without having to resort to stoichiometric or additional dehydrating agents.

All Non‐Carbon B3NO2 Exotic Heterocycles: Synthesis, Dynamics, and Catalysis

“…[32] Steroidal acid reacted smoothly without any degradation with two free secondary alcohols barely affecting the catalysis (22), and the thiol unit was inert (23). The successful amidation of Boc-Glu-OtBu illustrated that the tBu ester and Boc protecting groups were compatible in the current catalytic system (24). a,b-Unsaturated acids served as suitable substrates irrespective of the presence of the a-a nd/or b-substituents, and the polyene system remained intact (25,26).…”

“…A recent mechanistic investigation led by Whiting provided more in‐depth information regarding boronic acid catalysis, in which dimerized boronates were responsible for effective catalysis . The involvement of multiple boron atoms gained increasing support from Ishihara's independent study on boronic acid catalysis and diboron‐catalyzed amidation revealed by Saito . Yamamoto has recently disclosed that Group 5 metal salts exert a particular catalytic function to promote ester–amide exchange as a practical alternative to efficiently produce high‐value amides and oligopeptides .…”

“…[22] The involvement of multiple boron atomsg ained increasing support from Ishihara's independent study on boronic acid catalysis [23] and diboron-catalyzed amidation revealed by Saito. [24] Yamamoto has recently disclosed that Group 5m etal salts exert ap articular catalytic function to promotee ster-amide exchange as ap ractical alternative to efficientlyp roduce high-value amides and oligopeptides. [25] Given the increasing focus on reliable waste-free catalytic amidation protocols in industry, [26,27] the development of ar eadily availabler obustc atalytic system that offers ab road substrate scope with practical tolerance is in high demand.…”

Synthesis of Arylacetaldehydes by Iridium‐Catalyzed Arylation of Vinylene Carbonate with Arylboronic Acids

“…Several experiments were conducted to gain insight into the role of B 2 (OH) 4 [16,17,19,20] as an additive in ac atalytic amount in the present iridium-catalyzed reaction (Scheme 3). Ther eaction of vinylene carbonate (1)w ith arylboronic acid 2a was repeated both with and without B 2 (OH) 4 at 70 8 8Cfor 15 min.…”

“…[13] After extensive screening it was found that the vinylene carbonate realizes formylmethylation of arylboronic acids giving arylacetaldehydes in the presence of an iridium catalyst. Table 1s ummarizes the results obtained for optimizing the reaction conditions.T he presence of B 2 (OH) 4 [16,17] in acatalytic amount (5.5 mol %) is essential for the production of arylacetaldehyde.W ithout B 2 (OH) 4 under otherwise the same conditions,t he yield of 3a is merely 19 %w ith al ow conversion of vinylene carbonate (1)(entry 2). Table 1s ummarizes the results obtained for optimizing the reaction conditions.T he presence of B 2 (OH) 4 [16,17] in acatalytic amount (5.5 mol %) is essential for the production of arylacetaldehyde.W ithout B 2 (OH) 4 under otherwise the same conditions,t he yield of 3a is merely 19 %w ith al ow conversion of vinylene carbonate (1)(entry 2).…”