Oxidant-controlled divergent transformations of 3-aminoindazoles for the synthesis of pyrimido[1,2-b]-indazoles and aromatic nitrile-derived dithioacetals

Abstract

An oxidant-controlled divergent reactivity of 3-aminoindazoles is presented, which enables the [3 + 3] annulation and C–H arylation of ketene dithioacetals in disparate pathways to assemble pyrimido[1,2-b]-indazoles and aromatic nitrile-derived dithioacetals.

Cu-Catalyzed Oxidative Dual Arylation of Active Alkenes: Preparation of Cyanoarylated Oxindoles through Denitrogenation of 3-Aminoindazoles

“…According to the presented results and reported literature, ,,− we proposed a possible mechanism for this Cu-catalyzed oxidative dual arylation of acrylamides with 3-aminoindazoles in the presence of Cu­(OAc) 2 and aq. TBHP (Scheme ).…”

“…In the past several years, 3-aminoindazoles were key intermediates in organic chemistry and pharmaceutical industry . 3-Aminoindazoles could undergo two different types of reactions, including denitrogenative coupling reactions and condensation with carbonyl compounds., Recently, Song and co-workers proposed Cu-catalyzed oxidative denitrogenative coupling of 3-aminoindazoles with enamines to afford 1-aminoisoquinolines (path I, Scheme ). In 2018, the denitrogenative cross-coupling of 3-aminoindazoles with aromatic heterocycles was also developed by the same group (path II, Scheme ).…”

“…Although 3-aminoindazoles are widely used in organic synthesis, , efficient methods for selective oxidative dual arylation of carbon–carbon double bonds in acrylamides with 3-aminoindazoles are lacking. Inspired by these results, we conceive that 3-aminoindazoles can go through the two-C–N-bond cleavage to afford cyano-substituted aryl radicals in the assistance of a Cu catalyst and oxidant.…”

Indoleninyl-substituted pyrimido[1,2-b]indazoles via a facile condensation reaction

“… 5 The addition of metal catalysts such as CuSO 4 ·5H 2 O, Al(OTf) 3 , and Cu(OAc) 2 also enhances the transformation of such products. 6 However, this method is only feasible with specific functional groups, hence there is a limitation in the synthesis of structurally diverse derivatives.…”

Cu-Catalyzed Denitrogenative Transannulation of 3-Aminoindazoles To Assemble 1-Aminoisoquinolines and 3-Aminobenzothiophenes

“…Although the denitrogenative transannulations of triazoles, benzotriazinones, and tetrazoles have been previously studied, the denitrogenative transannulation of 3-aminoindazoles has never been reported so far. As part of our ongoing interest in exploring new reactions of 3-aminoindazoles, herein, we describe a novel Cu-catalyzed denitrogenative transannulation of 3-aminoindazoles to afford diverse functionalized 3-aminobenzothiophenes and 1-aminoisoquinolines (Scheme c).…”