DDQ in mechanochemical C–N coupling reactions

Abstract

2,3-Dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) is a commonly known oxidant. Herein, we report that DDQ can be used to synthesize 1,2-disubstituted benzimidazoles and quinazolin-4(3H)-ones via the intra- and intermolecular C–N coupling reaction under solvent-free mechanochemical (ball milling) conditions. In the presence of DDQ, the intramolecular C(sp2)–H amidation of N-(2-(arylideneamino)phenyl)-p-toluenesulfonamides leads to 1,2-disubstituted benzimidazoles and the one-pot coupling of 2-aminobenzamides with aryl/alkyl aldehydes resulted in substituted quinazolin-4(3H)-one derivatives in high yields.

Tandem Reduction, Ammonolysis, Condensation, and Deamination Reaction for Synthesis of Benzothiadiazines and 1-(Phenylsulfonyl)-1H-benzimidazoles

“…2-Nitro- N -phenylbenzenesulfonamide and its derivatives ( 1 ), , N -(2-nitrophenyl)­benzenesulfonamide and its derivatives ( 3a – 3x ), N -(2-nitrophenyl)­pyridin-2-amine ( 3ab ), and N -(2-aminophenyl)-4-methylbenzenesulfonamide ( 7 ) were commercially available or prepared by standard procedures.…”

Dissecting Mechanochemistry III

“…Further, Moores and co-workers synthesized phosphorusbridged heptazine-based carbon nitrides (g-h-PCN) from an initial mechanical treatment of trichloroheptazine and Na 3 P, once again highlighting the importance of halogenated organic molecules as building blocks for graphitic heptazine materials (Scheme 4) [8]. Another halogenated molecule, 2,3-dichloro-5,6-dicyano-1,4benzoquinone (DDQ), proved to be an appropriate oxidant for C-N couplings towards the synthesis of 1,2-disubstituted benzimidazoles and quinazolin-4(3H)-one derivatives under mechanochemical conditions, as evidenced by Mal and co-workers (Scheme 5) [9]. However, the findings within Mechanochemistry III span beyond the synthesis or the use of halogenated compounds and include the mechanochemical preparation of isocyanides [10], formylated and acetylated amines [11], and the mechanosynthesis of unsymmetrical salens ligands for preparing metal-salen catalysts [12].…”

“…Another halogenated molecule, 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ), proved to be an appropriate oxidant for C–N couplings towards the synthesis of 1,2-disubstituted benzimidazoles and quinazolin-4(3 H )-one derivatives under mechanochemical conditions, as evidenced by Mal and co-workers ( Scheme 5 ) [ 9 ].…”

Well‐Defined Mn(II)‐complex Catalyzed Switchable De(hydrogenative) Csp3‐H Functionalization of Methyl Heteroarenes: A Sustainable Approach for Diversification of Heterocyclic Motifs

“…The authors have cited additional references within the Supporting Information (Ref. [30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49]).…”