Nitul Ranjan Guha

A solid supported palladium(0) nano/microparticle catalyzed ultrasound induced continuous flow technique for large scale Suzuki reactions

An ultrasound-induced continuous flow technique was developed for the solid supported palladium(0) nano/microparticle (SS-Pd) catalyzed Suzuki cross coupling reaction of haloarenes (chloro, bromo and iodo) with phenyl boronic acid on a gram scale. An externally conjugated reservoir was fitted for easy operation of the reaction in water under mild basic conditions. The SS-Pd catalyst was found to be very stable in aqueous media, easily separable and recyclable up to five runs without significant loss of activity. Furthermore, the scaling of the well known Suzuki reaction up to 5 g scale under mild ultrasonic irradiation can be of industrial interest in the future.

Oxidative “reverse-esterification” of ethanol with benzyl/alkyl alcohols or aldehydes catalyzed by supported rhodium nanoparticles

A very unusual role of polystyrene stabilized rhodium (Rh@PS) nanoparticles as a supported catalyst is described for “reverse-esterification” of ethanol with benzyl/alkyl alcohols or aldehydes. Faster and selective oxidation of ethanol to acetaldehyde and H2 under Rh@PS catalyzed conditions which restricted further oxidation of benzyl/alkyl alcohols and their in situ reaction gave the corresponding acetate esters following the dehydrogenative-coupling approach. A hitherto redox dehydrogenative-coupling of ethanol and aldehydes has also been explored for the same acetate ester synthesis under Rh@PS catalyzed conditions.

Microwave assisted solvent and catalyst free method for novel classes of β-enaminoester and acridinedione synthesis

Novel classes of β-enaminoesters were synthesized using our newly described ethyl-3-(2,4-dioxocyclohexyl)propanoate molecule (1) under solvent and catalyst free microwave assisted conditions. No work-up procedure, milder reaction conditions, wide substrate scope and high yields add extra importance to this method and open up the scope for acridinediones as well as peptidomimetic molecule synthesis.

Polystyrene trimethyl ammonium chloride impregnated Rh(0) (Rh@PMe3NCl) as a catalyst and methylating agent for esterification of alcohols through selective oxidation of methanol

Rhodium(0) nanoparticle (NP)-impregnated polystyrene trimethyl ammonium chloride (PMe3NCl) resin (Rh@PMe3NCl) under basic conditions acts as a cross-dehydrogenative coupling-methylating (CDCM) agent for the selective oxidation of methanol and its in situ reaction with benzyl/alkyl alcohols allowing methyl group transfer for acetate ester synthesis in a tandem approach. The redox property of methanol which restricts the oxidation of benzyl/alkyl alcohols for product formation is critically investigated.

Solid Supported Palladium(0) Nanoparticles: An Efficient Heterogeneous Catalyst for Regioselective Hydrosilylation of Alkynes and Suzuki Coupling of β-Arylvinyl Iodides

The solid supported palladium(0) nanoparticles (NPs) were found as an active heterogeneous catalyst for regioselective hydrosilylation of alkynes with organosilanes in the presence of NaI as additive. Aliphatic as well as aromatic terminal/substituted alkynes with both electron releasing and withdrawing functionalities similarly participated in the hydrosilylation to produce regioselective β-isomers of vinylsilanes under mild reaction conditions. Reducible functional groups such as nitrile, ester, halide, alkene and alkyne were also found to be tolerated under this condition. Furthermore, the triethylsilylstyrene was applied for consecutive iododesilylation followed by Suzuki coupling reaction to produce stilbenes. The air/moisture stable SS–Pd catalyst was recycled for hydrosilylation reaction up to ten runs without significant loss of its catalytic activity.Graphical AbstractSolid Supported Palladium(0) Nanoparticles: An Efficient Heterogeneous Catalyst for Regioselective Hydrosilylation of Alkynes and Suzuki Coupling of β-Arylvinyl Iodides