A Catalyst and Solvent Free Route for the Synthesis of N-Substituted Pyrrolidones from Levulinic Acid

An efficient, metal-free, catalyst-free and solvent-free methodology for the reductive amination of levulinic acid with different anilines has been developed using HBpin as the reducing reagent. This protocol offers an excellent method to avoid solvents and added catalysts on the synthesis of different kinds of N-substituted pyrrolidones under metal free conditions. It is also the first report for the synthesis of different pyrrolidones by solvent-free as well as catalyst-free methods. The proposed mechanism for the formation of pyrrolidone has been supported by DFT calculations and control experiments.

Insights into Cascade and Sequential one pot pathways for reductive amination of aldehydes paired with bio-derived levulinic acid to N-substituted pyrrolidones using molecular hydrogen

This work aims to explore cascade and sequential one pot syntheses pathways for N-substituted pyrrolidones from aryl aldehydes and bio-derived levulinic acid (LA) using molecular hydrogen and ammonia. This process...

Metal-Free Cascade Formation of Intermolecular C-N Bonds Accessing Substituted Isoindolinones under Cathodic Reduction

An electrochemical protocol for the construction of substituted isoindolinones via reduction/amidation of 2-carboxybenzaldehydes and amines has been realized. Under metal-free and external-reductant-free electrolytic conditions, the reaction achieves the cascade formation of intermolecular C-N bonds and provides a series of isoindolinones in moderate to good yields. The deuterium-labeling experiment proves that the hydrogen in the methylene of the product is mainly provided by H₂O in the system.

Electroselective and Controlled Reduction of Cyclic Imides to Hydroxylactams and Lactams

An efficient and practical electrochemical method for selective reduction of cyclic imides has been developed using a simple undivided cell with carbon electrodes at room temperature. The reaction provides a useful strategy for the rapid synthesis of hydroxylactams and lactams in a controllable manner, which is tuned by electric current and reaction time, and exhibits broad substrate scope and high functional group tolerance even to reduction-sensitive moieties. Initial mechanistic studies suggest that the approach heavily relies on the utilization of amines (e.g., i-Pr₂NH), which are able to generate α-aminoalkyl radicals. This protocol provides an efficient route for the cleavage of C-O bonds under mild conditions with high chemoselectivity.

Convenient and efficient synthesis of novel 11H-benzo[5,6][1,4]thiazino[3,4-a]isoindol-11-ones derived from 2-bromo-(2/3-substitutedphenyl)-1H-indene-1,3(2H)-diones

An unprecedented formation of 11H-benzo[5,6][1,4]thiazino[3,4-a]isoindol-11-ones through a one-step reaction of differently substituted 2-aminobenzenethiols and 2-bromo-(2/3-substitutedphenyl)-1H-indene-1,3(2H)-diones in freshly dried ethanol under reflux conditions has been investigated. This unique transformation probably occurs through an initial nucleophilic substitution followed by ring opening and subsequent intramolecular cyclization. The structures of all the synthesized benzo[1,4]thiazino isoindolinones were established by FTIR, ¹H NMR, ¹³C NMR, HRMS, and X-ray crystallographic analysis. This approach was found to be simple and convenient and provides several advantages such as substantial atom economy, short reaction time and operational simplicity.

A metal-free and convenient approach to the synthesis of novel 11H-benzo[5,6][1,4]thiazino[3,4-a]isoindol-11-ones (5) is described.

Highly Regioselective Synthesis of Substituted Isoindolinones via Ruthenium-Catalyzed Alkyne Cyclotrimerizations

(Cyclooctadiene)(pentamethylcyclopentadiene)ruthenium chloride [Cp*RuCl(cod)] has been used to catalyze the regioselective cyclization of amide-tethered diynes with monosubstituted alkynes to give polysubstituted isoindolinones. Notably, the presence of a trimethylsilyl group on the diyne generally led to complete control over the regioselectivity of the alkyne cyclotrimerization. The cyclization reaction worked well in a sustainable non-chlorinated solvent and was tolerant of moisture. The optimized conditions were effective with a diverse range of alkynes and diynes. The 7-silylisoindolinone products could be halogenated, protodesilylated or ring opened to access a range of usefully functionalized products.

Ruthenium catalysts for hydrogenation of aromatic and aliphatic esters: make use of bidentate carbene ligands

Committed carbenes: The convenient application of bidentate carbene ligands is described for the hydrogenation of carboxylic acid esters. The ligand precursors are easily synthesized through the dimerization of N-substituted imidazoles with diiodomethane. The catalyst is generated in situ and exhibits good activity and functional group tolerance for the hydrogenation of aromatic and aliphatic carboxylic acid esters.