T. Punniyamurthy

Cobalt catalyzed oxidation of cyclic alkenes with molecular oxygen: allylic oxidation versus double bond attack

Cobalt(II) Schiffs base complex 1 and 2 exhibit a remarkable chemoselectivity during oxidation of cyclic alkenes with molecular oxygen in the presence of 2- methylpropanal. Catalyst 1 encourages the oxidation of double bond to give epoxide as the major product whereas catalyst 2 promotes mainly the allylic oxidation leading to allylic alcohols or enones.

Cobalt(II) catalyzed biomimetic oxidation of hydrocarbons in the presence of dioxygen and 2-methylpropanal

Cobalt(II) Schiff base complex 1 catalyses the oxidation of aliphatic and aromatic hydrocarbons in the presence of 2-methylpropanal under 1 atmosphere of dioxygen to give corresponding ketones and alcohols.

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 catalyzed oxidation of secondary alcohols with dioxygen in the presence of 2-methylpropanal

Cobalt schiff base complex 2 catalyses the oxidation of a wide range of secondary alcohols to the corresponding ketones in the presence of dioxygen and 2-methylpropanal.

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 catalysed allylic and benzylic oxidations with dioxygen in the presence of ethyl 2-oxocyclopentanecarboxylate

An efficient allylic and benzylic oxidation of various cyclic alkenes and benzylic compounds respectively can be achieved with dioxygen in the presence of ethyl 2-oxocyclopentanecarboxylate 2 and catalytic amount of cobalt(II) Schiffs base complex 1.

Polyaniline supported cobalt(II) salen catalysed synthesis of pyrrolidine containing α-hydroxyamide core structures as inhibitors for HIV proteases

A novel synthesis of pyrrolidine containing α-hydroxyamide core structures as inhibitors for HIV protease is developed by employing polyaniline supported cobalt (II) salen catalysed formation of the epoxide from cinnamoylamides of L-proline followed by its opening with anilines at ambient condition.

Cobalt(II) Schiff base catalyzed biomimetic oxidation of organic substrates with dioxygen

Cobalt(II) Schzrbase complexes 1, 2 and 3 catalyze the oxidation of a wide range of organic substrates in the presence of carbonyl compounds and dioxygen. EPR studies on 1 indicate that these reactions are proceeding via a cobalt(1II)-superoxo complex formed under the aegis of carbonyl compounds and dioxygen. Catalysts 1-3 exhibit diverse reactivity profile and this has been attributed to the nature of ligand around cobalt which causes the formation of direrent active species from dioxygen.

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) Schiff's base complex catalysed oxidation of alcohols with dioxygen in the presence of ethyl 2-oxocyclopentanecarboxylate

Abstract Cobalt(II) Schiffs base complex 1 catalyses the oxidation of primary and secondary alcohols to aldehydes and ketones respectively, in the presence of dioxygen and ethyl 2-oxocyclopentanecarboxylate 2 at 60–70° C.