Visible-light-mediated metal-free decarboxylative acylations of isocyanides with α-oxocarboxylic acids and water leading to α-ketoamides

Abstract

A novel visible-light-induced and Rose Bengal catalyzed strategy has been developed for the synthesis of α-ketoamides via decarboxylative acylations of isocyanides with α-oxocarboxylic acids and water under mild conditions.

Photocatalytical and Photochemical Generation of Imidoyl Radicals: Synthetic Applications

“…The same group again demonstrated rose bengal catalysed decarboxylative acylation of isocyanides 166 with α‐oxocarboxylic acids 171 and water to access α‐ketoamides 172 (Scheme 36). [79] Here, they propose that SET occurs from α‐oxocarboxylic acid [E 1/2 =−1.6 to −2.2 V vs . SCE] [46] to excited state RB* [RB*/RB .− ; E 1/2 =+0.99 V vs .…”

“…The same group again demonstrated rose bengal catalysed decarboxylative acylation of isocyanides 166 with α-oxocarboxylic acids 171 and water to access αketoamides 172 (Scheme 36). [79] Here, they propose that SET occurs from α-oxocarboxylic acid [E 1/2 = À 1.6 to À 2.2 V vs. SCE] [46] to excited state RB* [RB*/ RB *À ; E 1/2 = + 0.99 V vs. SCE] to produce α-oxocarboxylic acid radical cation and RB *À . Then RB *À [RB *À /RB; E 1/2 = À 0.78 V vs. SCE] gets oxidized by aerial oxygen [E 1/2 = + 0.30 V vs. SCE] [77] to complete the catalytic cycle with the regeneration of RB and formation of O Very recently, we came across with a visible light assisted isocyanide-based multicomponent (MCR) domino cascade approach for the stereoselective syn-thesis of iminofurans 178 (Scheme 37).…”

Copper-catalyzed synthesis of α-ketoamides using water and dioxygen as the oxygen source

“…In 2019, Wei and co-workers reported the transformation of a-ketoacids with isocyanides to a-ketoamides using water as the oxygen source. 20 Multicomponent reaction has emerged as a powerful protocol to construct complex organic compounds. 21 The present multicomponent reaction of copper-catalyzed direct oxidative transformation of alkynes and secondary amines to a-ketoamides is realized at room temperature without any ligand or additive, in which H 2 O and O 2 were employed as the co-oxygen source (eqn (1)).…”

Cu-catalyzed cross-coupling of methyl ketones and pyridin-2-amines for the synthesis of N-(2-pyridyl)-α-ketoamides

“…Recently, transition-metal-catalyzed reactions have become powerful tools for the formation of carbon-nitrogen bonds to prepare amides. [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25] Ahmed and colleagues 26 reported a unique dimethyl sulfoxide (DMSO)-promoted oxidative amidation approach for synthesis of α-ketoamides from 2-oxoaldehydes and aliphatic amines (Scheme 1(a)); Zhang and Wang 27 and Wan and colleagues 28 independently developed a facile TBHP/I 2 -promoted oxidative coupling reaction of acetophenones with aliphatic amines for the synthesis of α-ketoamides (Scheme 1(b)); Kaliappan and colleagues 29 has described a one-pot copper-catalyzed biomimetic route to N-heterocyclic amides from methyl ketones and pyridin-2-amines (Scheme 1(c)). Although numerous investigations in this field have been conducted, the development of a new strategy is still highly desirable for the construction of αketoamides, which are an important class of amide compounds with the general structure (R 1 COCONR 2 ).…”