Dr. S Adimurthy's Group

1. Copper catalysed aerobic oxidative Chemistry. 

Copper-catalysts have emerged as powerful tool for the wide range of organic transformations like C-H functionalization, cross coupling reactions olefin metathesis and material synthesis. Recently using copper as catalyst the development of new powerful synthetic methodologies and new types of chemical compounds. The recent highly developing in field of transition metal catalysed oxidative functionalization of C-H bonds, hence, to avoiding pre-functionalization  substrates, using unsubstituted substrates which are cheaper and have (green) advantages such as the avoidance of halogen side-products. Based on above significant, several transition metal catalyst (Pd, Ru, Rh, Au, and Ni) are developed with using of stoichiometric oxidant, such as O2, PhI(OAc)2, benzoquinone, CuII or AgI, are required to achieve catalytic turnover. However, many of the most of the transition metals (Pd, Ru, Rh, Au, and Ni) are not compatible with the use of O2. Utilization of oxygen as oxidant in C-H functionalization is a highly atom-economical, environmentally benign, and abundant oxidant, which makes it ideal in many ways like H2O only by product and high selectivity. In combination of chemistry of copper with oxygen verity of organic transformations increases exponentially.  Oxygen can act as either a sink for electrons (oxidase activity) or a source of oxygen atoms that are incorporated into the product (oxygenase activity) or both. The oxidation of copper with oxygen is a facile process allowing catalytic turnover in net oxidative processes and ready access to the higher Cu(III) oxidation state, which enables a range of powerful transformations including two-electron reductive elimination to CuI. (Figure )

 

 

 

 

 

 

 

 

 

 

 

 

 

 

                             Figure. Application of copper catalysed aerobic oxidative C-H functionalization reactions

 

[A] Synthesis of bio active heterocyclic compound

 

Since last decade, the verities of heterocyclic compounds are synthesized through copper-catalyzed C–H functionalization of Sp, Sp2, and Sp3- carbons. We have developed copper-catalyzed efficient oxidative C-N bond formations for synthesis of variety of heterocycles such as imidazo(1,2-a)pyridines, imidazo(1,5-a)pyridines, pyrazolo[1,5-a]pyridines and indolizines via C-H functionalization of pyridine derivatives and other commercially available substrates.(Scheme )

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

                      Scheme : Copper catalyzed synthesis of bioactive aza-heterocycles

 

[B] Oxidative C-N bond formation reactions

 

We are also focusing on copper catalysed aerobic oxidative C-N bond formation of benzyl amines to imines and metal free oxidative C-N bond formations.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

                                                   

 

                                              Scheme . Oxidative C-N bond formation reactions

 

2. Amid/peptide bond synthesis

 

The amide bond is one of the most important linkages in nature due to its presence in peptides and protein structures and has been well recognized in chemistry and biology. In addition, amides serve as versatile intermediates for the preparation of pharmaceuticals, agrochemicals, polymers, and materials. Traditional method for synthesis of amides are shown Scheme 3. Our research is focusing on new development of new synthetic routs for the synthesis of amides (scheme )

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

                                             Scheme. Traditional method for synthesis of amides

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

                                                    Scheme. Transamidation Reactions

 

 

3. Green halogenation/Sustainable chemistry

 

[A]. Eco-friendly and versatile brominating reagent, Green Bromine (GB) prepared from salt bittern

 

This area of research focus on applications of bromide-bromate couple in organic synthesis. The couple having 5:1 mole ratio of bromide to bromate is useful for preparation of dibromo derivatives from alkenes/alkynes. The 2:1 couple affects substitution with high bromine atom efficiency. Vicinal functionalization of olefins has also been studied. The 1:8 bromide-bromate couple has proved promising in several oxidation reactions, the performance exceeding that of bromate alone. This reagent was also the most effective for deiodination of styrene-based iodohydrins with concomitant rearrangement by a novel pathway. In all the cases the reagents were activated through in situ acidification. The 5:1 reagent is obtained as intermediate during liquid bromine manufacture and the other reagents were prepared from it using ClO-. Liquid bromine could be avoided in the product life cycle.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

                                                     Figure. Preparation of Green Bromine (GB)

 

 

[B]. Synthetic application of Green brominating (GB) reagent 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

                            Scheme. Synthetic applications of Green brominating reagent