Beena Bhatia

A versatile cobalt(II)-Schiff base catalyzed oxidation of organic substrates with dioxygen: Scope and mechanism

Abstract Cobalt(II) complex 1a-f derived from Schiff bases act as efficient catalysts during the oxidation of wide range of organic substrates(e.g. alkenes, alcohols, benzylic compounds and aliphatic hydrocarbons) with dioxygen in the presence of aliphatic aldehydes or ketones or ketoesters. EPR studies on 1a-f complexes suggest that the aliphatic carbonyl compounds promote the formation of a cobalt(III)-superoxo species responsible for the oxidation of organic compounds. These studies also demonstrate the role of ligands on cobalt in controlling the chemoselectivity of these oxidations. A plausible mechanistic rational is also provided for these oxidations.

Cobalt-catalysed three-component coupling involving ketones or ketoesters, aldehydes and acetonitrile: a novel one-pot synthesis of β-acetamido ketones

Cobalt(II) chloride catalyses one-pot coupling of ketones or ketoesters, aldehydes and acetonitrile in the presence of acetyl chloride to give β-acetamido ketones 3 in good yields.

Cobalt(II) catalysed reaction of alkenes with aliphatic aldehydes and molecular oxygen: scope and mechanism

Abstract A variety of cobalt(II) complexes can be prepared using Schiffs bases derived from aromatic aldehydes and amines or α-aminoesters. These complexes are versatile catalyst for the reaction between aliphatic aldehydes and various alkenes. The outcome of the reaction is controlled by the electronic nature of the alkene as the electron deficient alkenes undergo oxidative addition of aldehydes followed by dioxygen incorporation to yield 2-hydroxy(acyloxy)-4-oxoesters or nitriles whereas unactivated or electron rich alkenes afford the corresponding epoxides. These reactions are proceeding via a radical pathway and a common acylcobalt intermediate is proposed for the formation of 4 as well as the epoxides 7.

Cobalt (II) acetate promoted oxidative additioh of 1,3-dicarbonyl compounds to alkenes under aerobic conditions

Abstract The reaction of 1,3-dicarbonyl compounds with various alkenes in presence of Co(OAC)2. XH2O under aerobic conditions gives dihydrofurans in moderate to good yields. The role of dioxygen is discussed by comparing these reactions under anerobic conditions.

Cobalt(II) catalysed epoxidation of unfunctionalised alkenes with in situ generated hydroperoxide from methyl-2-oxocyclopentane carboxylate and molecular oxygen

Cobalt(II) complex 1 catalyses the epoxidation of unfunctionalised alkenes by in situ generated hydroperoxide from methyl-2-oxocyclopentane carboxylate and molecular oxygen.

Cobalt (II) catalysed allylation of 1,3-dicarbonyl compounds with allyl acetates

An efficient allylation of various 1,3-dicarbonyl compounds can be achived with allyl acetates in the presence of catalytic cobalt (II) chloride in 1,2-dichloroethane.

A cobalt catalyzed protocol for the synthesis of substituted β-phenyl isoserine derivatives

A versatile Cobalt Catalysed protocol for the epoxidation of α-β unsaturated esters or amides followed by its cleavage with aniline and its derivatives to afford substituted β-phenylv isoserine derivative has been developed.

Cobalt (II) catalyzed oxidation of aldehydes to carboxylic acid with molecular oxygen

A variety of aromatic and some aliphatic aldehydes are efficiently transformed to the corresponding carboxylic acid in presence of catalytic amount of Cobalt (II) chloride, molecular oxygen and acetic anhydride at room temperature. Phenolic aldehydes undergo acylative oxidation to give the corresponding acylated carboxylic acid.

A one pot synthesis of β-acetamido ketones and furans by cobalt(II) catalyzed coupling of 1,3- or 1,4- dicarbonyl compounds and aldehydes: a remarkable role of dioxygen

Cobalt(II) catalyses the coupling of 1,3- and 1,4-dicarbonyl compounds with various aldehydes in the presence of acetonitrile to give β-acetamido ketones and furan amides respectively. The outcome of these reactions is controlled by the reaction atmosphere as aromatic aldehydes react to give β-ketoamide in the presence of nitrogen, whereas the reaction with aliphatic aldehydes gives the later product only in the presence of oxygen atmosphere.

Cobalt catalyzed regioselective allylation of 1,3-dicarbonyl compounds

Catalytic amount of Cobalt(II) chloride in 1,2-dichloroethane promotes the allylation of 1,3-dicarbonyl compounds with allyl acetates in high yields. The allylation of pentane-2,4-dione is highly regioselective as compared with methylacetoacetate and ethyl 2-oxocyclopentanecarboxylate.