Silver-Catalyzed Nucleophilic Addition of β-Dicarbonyls to Isocyano Group: Facile Access to Indolin-3-ol Derivatives

Abstract

A domino silver-catalyzed intermolecularly nucleophilic addition of β-dicarbonyls to the isocyano group and cyclization of the imidoyl silver sequence was developed for the direct and efficient synthesis of indolin-3-ol derivatives. This domino transformation tolerates a range of readily available o-acyl arylisocyanides and 1,3-dicarbonyls under an operationally simple procedure. Triple roles of silver carbonate are demonstrated in this reaction: (1) activation of isocyano group, (2) formation of enolate, and (3) promotion the nucleophilic reactivity of imidoyl intermediate.

Copper-Catalyzed Chemoselective Cyclization Reaction of 2-Isocyanoacetophenone: Synthesis of 4-Hydroxyquinoline Compounds

“…After the reaction was completed, the mixture was solid recrystallized (EtOH) and reduced by H 2 (balloon) and Pd/C (Palladium 10% on activated carbon, 100 mg) in ethyl acetate to afford 1-(2-aminophenyl)-3-phenylpropan-1-one. Then according to the literature procedures the typical formylation and dehydration procedure was used to afford desired 2-isocyano­aceto­phenone.…”

“…Concentrated hydrochloric acid (5 mL) and surfactant CTAB (hexadecyl trimethyl­ammonium bromide, 5.5 g, 1.5 equiv, 15 mmol) were mixed with 2-ethynylaniline to stir at 80 °C for 12 h in distilled water to generate substituted 2-aminoecetophenone. Then according to the literature procedures the typical formylation and dehydration procedure was used to afford desired 2-isocyano­acetophenone.…”

“…Besides the well-known multicomponent Ugi , and Passerini reactions, isocyanides insertion and cyclization reaction powerful strategies for the preparation of nitrogen-containing heterocycles. , In view of their high reaction activities and variabilities, the application of isocyanides has drawn considerable attention. Notably, 2-isocyano­aceto­phenone derivatives were easily available starting materials for the construction of various heterocyclic compounds in recent years. − In 2009, Konishi and co-workers reported a simple method for the synthesis of 4-alkylidene-4 H -3,1-benzoxazine derivatives via acid-catalyzed cyclization of 2-isocyanophenyl ketones in the presence of vinyl ether . Later, cyclization reaction of 2-isocyano­aceto­phenone derivatives with sulfur and Eschenmoser’s salt were well developed for the preparation of corresponding nitrogen-containing heterocycles .…”

“…Recently, silver-catalyzed cyclization reaction of 2-isocyano­aceto­phenone derivatives with isocyano­acetamides has been developed for the facile and efficient synthesis of quinolones by the Xu group . As versatile building blocks, 2-isocyano­aceto­phenone derivatives have recently been employed in the assembly of indole-/furan-fused heterocycles, quinazolines, (Scheme , eq 2) and indolin-3-ol derivatives . Among these transformations, isocyanides attacked by a nucleophile is indispensable.…”

“…(Palladium 10% on activated carbon, 100 mg) in ethyl acetate to afford 1-(2-aminophenyl)-3-phenylpropan-1-one. Then according to the literature procedures 12 the typical formylation and dehydration procedure was used to afford desired 2-isocyanoacetophenone. Method B.…”