Potassium Iodide/tert‐Butyl Hydroperoxide‐Mediated Oxidative Annulation for the Selective Synthesis of N‐Substituted 1,2,3‐Benzotriazine‐4(3H)‐ones Using Nitromethane as the Nitrogen Synthon

Abstract

An ovela nd efficiento xidative annulation of 2-aminobenzamides with nitromethane has been developed for the chemoselective synthesis of N-substituted 1,2,3-benzotriazine-4(3H)-ones in moderate to excellent yields under transitionm etalfree conditions.T wo N À Nb onds were constructed in one pot via C À Nc leavage of nitromethane, which was selectively employed as the nitrogen synthon. Thep reliminary mechanistic studies revealed that this protocolproceeded under hypoiodite catalysis generated in situ.

Nitromethane as a nitrogen donor in Schmidt-type formation of amides and nitriles

“…1B). By contrast, the reactivity of nitromethane as a nitrogen donor has been scarcely developed (40). It was reported that the electrophilic nitroxyl species (HNO) could be generated through the Nef process (41, 42) (Fig.…”

One-pot synthesis of N-substituted benzannulated triazoles via stable arene diazonium salts

“…The reaction was carried out as described in the general procedure using 2-amino-N-(2'-methylphenyl)benzamide (6r) (0.100 g, 0.442 mmol), polymer-supported nitrite (0.379 g, containing 1.33 mmol of NO2) and p-toluenesulfonic acid monohydrate (0.252 g, 1.33 mmol). The reaction mixture was stirred at 0 °C for 1 h and then heated to 40 °C for N-(4'-Methylphenyl)-1,2,3-benzotriazin-4(3H)-one (7s) 14 The reaction was carried out as described in the general procedure using 2-amino-N-(4'-methylphenyl)benzamide (6s) (0.285 g, 1.26 mmol), polymer-supported nitrite (1.09 g, containing 3.78 mmol of NO2) and p-toluenesulfonic acid monohydrate (0.719 g, 3.78 mmol). The reaction mixture was stirred at 0 °C for 1 h and then heated to 40 °C for 4 h. The reaction mixture was cooled to room temperature and concentrated in vacuo.…”

“…Mp 147-150 °C (lit. 14 N-(4'-Fluorophenyl)-1,2,3-benzotriazin-4(3H)-one (7u) 14 The reaction was carried out as described in the general procedure using 2-amino-N-4'-fluorophenyl)benzamide (6u) (0.0500 g, 0.217 mmol), polymer-supported nitrite (0.187 g, containing 0.652 mmol of NO2) and p-toluenesulfonic acid monohydrate (0.124 g, 0.652 mmol). The reaction mixture was stirred at 0 °C for 1 h and then heated to 40 °C for 4 h. Purification by flash column chromatography, eluting with 30% ethyl acetate in hexane gave N-(4'-fluorophenyl)-1,2,3-benzotriazin-4(3H)-one (7u) (0.0320 g, 60%) as a white solid.…”

“…13 In addition, new approaches have been developed for the preparation of 1,2,3-benzotriazin-4(3H)-ones and 1,2,3benzothiatriazine-1,1(2H)-dioxides. 14 For example, Chandrasekhar and Sankararaman reported the preparation of N-substituted 1,2,3-benzotriazin-4(3H)-ones via the palladium(0)-catalysed carbonylation of 1,3-diaryltriazenes (Scheme 1b), 15 while Cui and co-workers prepared both series of compounds by a redox cyclisation of amides and School of Chemistry, The Joseph Black Building, University of Glasgow, Glasgow G12 8QQ, UK. Email: Andrew.Sutherland@glasgow.ac.uk †Electronic Supplementary Information (ESI) available: Experimental procedures and data for starting materials, 1 H and 13…”

Mechanistic Insights for Nitromethane Activation into Reactive Nitrogenating Reagents

“…Because of the strongly electron-withdrawing nitro (NO 2 ) group, nitromethane (CH 3 NO 2 ) is often used as carbon pro-nucleophile [3] as well as a common solvent. Recently, the reactivity of CH 3 NO 2 as nitrogen donor has been developed further using the mixture of either KI, tBuOOH, CsOAc and AcOH [4] or Tf 2 O, HCOOH and AcOH [5] as activating reagents. The transient nitroxyl species (HNO) was tentatively proposed as the crucial intermediate in such reactions, likely formed from the classical Nef reaction (i. e., acid hydrolysis of CH 2 NO 2 À salt to form H 2 CO and HNO).…”