A de novo Synthesis of Oxindoles from Cyclohexanone-Derived γ-Keto-ester Acceptors Using a Desaturative Amination–Cyclization Approach

Here we report a desaturative approach for oxindole synthesis. This method uses simple γ-ester-containing cyclohexanones and primary amine building blocks as coupling partners. A dual photoredox–cobalt manifold is used to generate a secondary aniline that, upon heating, cyclizes with the pendent ester functionality. The process operates under mild conditions and was applied to the modification of several amino acids, the blockbuster drug mexiletine, as well as the formation of dihydroquinolinones.

10.24.4 Product Subclass 4: Pyrazino[1,2-a]indoles and Related Benzo-Fused Ring Systems

The synthesis of pyrazino[1,2-a]indoles and related indolo[1,2-a]quinoxalines and pyrido[2′,1′:3,4]pyrazino[1,2-a]indol-5-ium salts are reviewed in this chapter. The most common routes to pyrazino[1,2-a]indoles involve cyclization of indole derivatives containing a formyl, keto, ester, or nitrile function at the 2-position. Indolo[1,2-a]quinoxalines are most readily accessed via cyclization of 1-(aryl)-1H-indoles, where the aryl group is substituted at the 2-position by either amino, iodo, or nitro functionality.

Synthesis of trisubstituted hydroxylamines by a visible light-promoted multicomponent reaction

A green and efficient route for the synthesis of trisubstituted hydroxylamines from β-keto ester, 2-nitrosopyridine and aryldiazoacetates has been reported. This multicomponent reaction occurred under mild conditions without catalysts or additives.

An Efficient One Pot Four-Component Synthesis of Spiro[indoline-3,4′-pyrano[2,3-c]pyrazole] Derivatives via Electrochemical Approach

An efficient, simple and one pot, synthesis of spiro[indoline-3,4′-pyrano[2,3-c]pyrazole] derivative by electrochemically induced condensation of β-keto ester, hydrazine hydrate, malononitrile or ethyl cyanoacetate and isatin in an undivided cell at constant current where sodium bromide was present as electrolyte in ethanol medium.

Straightforward Synthesis of Succinimide-Fused Pyrrolizidines by A Three-Component Reaction of α-Diketone, Amino Acid, and Maleimide

An efficient, one-pot, three-component [3+2] cycloaddition reaction of azomethine ylide obtained from α-dicarbonyl compounds (cyclic and acyclic diketone or keto ester) and amino acids with maleimides under catalyst-free conditions has been developed. This cascade protocol shows high efficiency and remarkable functional group tolerance, and the ubiquitous succinimide-fused pyrrolizidines with a highly compact and strained scaffold were obtained with high yield and excellent diastereoselectivity. Furthermore, this novel and atom-economical strategy could be performed on a gram scale with comparable reaction efficiency.