Isocyanide-based multicomponent reactions: concise synthesis of spirocyclic oxindoles with molecular complexity by using a [1,5]-hydrogen shift as the key step.

A concise multicomponent reaction of isocyanide, α-substituted allenoate, and methyleneindolinone has been disclosed. This protocol provides a fast and straightforward approach to synthesize unusual tricyclic oxindoles in an efficient and atom-economic manner. Mechanistically, the present cycloaddition may proceed through a cascade sequence involving double Michael addition, double cyclization, double [1,5]-hydrogen shift, and group migration. The introduction of a special alkyl group to the allenoate is believed to play a key role in the cascade reaction. This method also features a broad substrate scope, which is particularly useful for the delivery of a large number of compounds.

Palladium-catalyzed cascade reactions of enynones and isocyanides: access towards functionalized ketenimine and its application.

Palladium-catalyzed cascade reactions of enynones and isocyanides have been disclosed. This strategy allows for the synthesis of structurally unusual furan-incorporated ketenimines, which are stable and can undergo a formal [4+1] annulation with another isocyanide to yield indenone derivatives.

Phosphine-mediated sequential annulations of allenyl ketone and isocyanide: a bicyclization strategy to access a furan-fused eight-membered ring and a spirocycle.

Phosphine-mediated cascade annulations of allenyl ketone and isocyanide have been disclosed. Two molecular allenyl ketones work as different four-carbon synthons to form two rings, respectively, and thus enables the efficient synthesis of a furan-fused eight-membered ring and a spirocycle.

A formal (5+1) annulation reaction from heterodimerization of two different isocyanides: stereoselective synthesis of 2H-benzo[b][1,4]oxazin-2-one.

A novel (5+1) annulation reaction of functionalized 2-isocyanophenyloxyacrylate and aromatic, aliphatic isocyanides has been disclosed. This domino reaction involves the unusual heterodimerization of two different isocyanides and allows for a quick access to many 2H-benzo[b][1,4]oxazin-2-one derivatives.

Sequential cycloaddition and ring expansion reaction of arynes and methylenebenzothiopheneones: synthesis of a benzo-fused eight-membered ring via sulfonium ylides.

A sequential cycloaddition and ring expansion of arynes and methylenebenzothiopheneones has been disclosed. This strategy proceeds through a sulfonium ylides intermediate and allows for the efficient synthesis of a sulfur-containing benzo-fused eight-membered ring.

A bicyclization reaction with two molecular allenyl ketones and isocyanides: synthesis of a lactone-containing azaspirocycle derivative.

A novel bicyclization reaction of two molecular allenyl ketones and isocyanides has been disclosed. This strategy allows for the construction of structurally complex spirocyclic lactam-lactone systems in an efficient manner. This protocol also demonstrates other advantages such as high synthetic efficiency, atom economy, and broad substrate scope under mild conditions.

A domino reaction of 2-isocyanophenyloxyacrylate and aryne to synthesize arenes with vicinal olefin and benzoxazole.

An unusual domino reaction of 2-isocyanophenyloxyacrylate and aryne has been disclosed. The present strategy experiences nucleophilic addition, Michael addition, carbon-oxygen cleavage, and cyclization, thus enabling the quick aryne vicinal difunctionalization by the installation of a benzoxazole and an olefin.

Carbon-nitrogen bond cleavage of pyridine with two molecular substituted allenoates: access to 2-arylpyrimidin-4(3H)-one.

A DABCO-catalyzed annulation reaction of pyridin-2-amine and substituted allenoates has been disclosed. This strategy allows for the ring-opening of a pyridine ring system and the formation of two new rings including a pyrimidinone ring and a benzene ring in an efficient manner.

Multicomponent cascade cycloaddition involving tropone, allenoate, and isocyanide: a rapid access to a 7,6,5-fused tricyclic skeleton.

Multicomponent cascade cycloaddition of tropone, allenoate, and isocyanide has been disclosed. This method allows for the rapid construction of a highly unusual tricyclic skeleton in an efficient manner. The proposed transformation proceeds through [8 + 2 + 1] cycloaddition, [1,5]-H shift, and cyclization followed by an alkoxy group migration process.

Unexpected isocyanide-based cascade cycloaddition reaction with methyleneindolinone.

An unprecedented cascade reaction of isocyanide and methyleneindolinone has been established, which represents a novel and different reaction mode. This present transformation involves the ring-opening of methyleneindolinone and the construction of two other new rings simultaneously in an atom-economic manner.