Base-Controlled Reactions through an Aldol Intermediate Formed between 2‑Oxoaldehydes and Malonate Half Esters

A practical, atom-economical, base-directed, and highly efficient method for the generation of different selective products through a common aldol intermediate of 2-oxoaldehydes and malonate half esters is successfully developed. The addition of a strong basic environment (potassium <i>tert</i>-butoxide) catalyzed the synthesis of stable decarboxylative aldol products (α-hydroxy ketones), while the Doebner modification procedure resulted in decarboxylative elimination to (<i>E</i>)-α,β-unsaturated esters in good yields. The application of this method in one pot and one pot/two steps with azoles helped to develop regioselective α- and β-azolated products in appreciable yields

One-Pot Tandem Approach to Functionalized 3‑Hydroxy-2-furanyl-acrylamides

A novel one-pot tandem process involving Knoevenagel condensation, Michael addition, selective amidation, and Paal–Knorr cyclization to diverse functionalized 3-hydroxy-2-furanyl-acrylamides from simple 2-oxoaldehydes and aroylacetonitriles was presented. Attempts were also made to expand the scope of the reaction to different 2-heteroarylfurans. The packing diagram of the molecules viewed down along the α-axis of the unit cell showed a characteristic intramolecular classical O–H···O hydrogen bond between hydroxyl and carbonyl O atoms leading to self-associated (<i>Z</i>)-2-furanyl-acrylamides

One-Pot Tandem Approach to Functionalized 3‑Hydroxy-2-furanyl-acrylamides

A novel one-pot tandem process involving Knoevenagel condensation, Michael addition, selective amidation, and Paal–Knorr cyclization to diverse functionalized 3-hydroxy-2-furanyl-acrylamides from simple 2-oxoaldehydes and aroylacetonitriles was presented. Attempts were also made to expand the scope of the reaction to different 2-heteroarylfurans. The packing diagram of the molecules viewed down along the α-axis of the unit cell showed a characteristic intramolecular classical O–H···O hydrogen bond between hydroxyl and carbonyl O atoms leading to self-associated (<i>Z</i>)-2-furanyl-acrylamides

One-Pot Tandem Approach to Functionalized 3‑Hydroxy-2-furanyl-acrylamides

A novel one-pot tandem process involving Knoevenagel condensation, Michael addition, selective amidation, and Paal–Knorr cyclization to diverse functionalized 3-hydroxy-2-furanyl-acrylamides from simple 2-oxoaldehydes and aroylacetonitriles was presented. Attempts were also made to expand the scope of the reaction to different 2-heteroarylfurans. The packing diagram of the molecules viewed down along the α-axis of the unit cell showed a characteristic intramolecular classical O–H···O hydrogen bond between hydroxyl and carbonyl O atoms leading to self-associated (<i>Z</i>)-2-furanyl-acrylamides

A Ligand-Free Pd-Catalyzed Cascade Reaction: An Access to the Highly Diverse Isoquinolin-1(2<i>H</i>)-one Derivatives via Isocyanide and Ugi-MCR Synthesized Amide Precursors

A novel ligand-free palladium-catalyzed cascade reaction for the synthesis of highly diverse isoquinolin-1(2<i>H</i>)-one derivatives from isocyanide and amide precursors synthesized by Ugi-MCR has been developed. A broad variety of acids, amines, and isocyanides were used as starting materials for Ugi-MCR leading to various amide precursors, which in turn provided entry into diverse isoquinolin-1(2<i>H</i>)-one derivatives. The reaction proceeds through tandem isocyanide insertion with intramolecular cyclization followed by a Mazurciewitcz–Ganesan type sequence to provide isoquinoline-1(2<i>H</i>)-one derivatives in moderate to good yields

Access to Indole- And Pyrrole-Fused Diketopiperazines via Tandem Ugi-4CR/Intramolecular Cyclization and Its Regioselective Ring-Opening by Intermolecular Transamidation

An efficient approach for the synthesis of indole- and pyrrole-fused diketopiperazines has been developed. This protocol involves the Ugi four-component reaction (U-4CR) followed by an intramolecular cyclization of the Ugi products at room temperature to afford the desired products in good to excellent yields. In addition, it is interesting to report the subsequent regioselective ring-opening of diketopiperazine unit occurring via an intermolecular transamidation reaction under mild condition, resulting in the formation of highly functionalized indole-2-carboxamides and pyrrole-2-carboxamides

Metal-Free Oxidative Amidation of 2‑Oxoaldehydes: A Facile Access to α‑Ketoamides

A novel and efficient method for the synthesis of α-ketoamides, employing a dimethyl sulfoxide (DMSO)-promoted oxidative amidation reaction between 2-oxoaldehydes and amines under metal-free conditions is presented. Furthermore, mechanistic studies supported an iminium ion-based intermediate as a central feature of reaction wherein C₁-oxygen atom of α-ketoamides is finally derived from DMSO