For the first time we have synthesized Enantiopure Galactose Oxidase (GO) model using chiral BINAM-copper complex and used it as catalyst for aerobic oxidation of racemic secondary alcohols. By using this chiral GO model as catalyst, we have synthesized several chiral benzoins by AOKR of racemic benzoins at 60 oC with enantiomeric excess up to 98%. Further to improve the efficiency and selectivity of the AOKR under milder reaction conditions, a new chiral cobalt complex was developed for AOKR of racemic benzoins at room temperature and very good enantiomeric excess (up to 99.5%) and selectivity (s up to 47) were achieved. For the first time we have used easily available chiral iron catalyst for AOKR of racemic benzoins with good selectivity. Also, we have synthesized amino alcohols and a-hydroxy esters almost in enantiomerically pure form using our above-mentioned chiral catalysts.
Our research group is involved in development of copper-catalyzed C(aryl)-N, C(aryl)-O, C(aryl)-S, and C(aryl)-C bond forming coupling reactions under mild reaction conditions. These protocols were applied for the synthesis of several heterocycles and biologically active molecules in shortest possible routes.
For the first time a novel, efficient and economical protocol was developed for synthesis of very important 1,4-benzoxazine or 1,4-benzothiazine moieties by domino aziridine ring opening reaction with o-iodophenols or o-halothiophenols followed by copper catalyzed Goldberg coupling cyclization using easily available ethylenediamine-CuI complex as catalyst with good to excellent yields.
The above-mentioned new reaction methodology was successfully extended to enantioselective non-enzymatic coupling kinetic resolution (CKR) of (±)-trans-N-�-(2-bromoaryloxy)-cycloalkyl sulfonamides to synthesize optically active 1,4-benzoxazine moieties by using commercially available (S)-BINAP-Pd(OCOCF3)2.
Also, we have developed a new copper-catalyzed methodology for in situ generation of thiols from aryl halides and xanthate as easily available thiol surrogate. This approach was successfully utilized for the one-pot synthesis of substituted aryl thioethers, benzothiazoles and benzothiophenes.
Chiral Nanocatalyst for Asymmetric synthesis:
Our group is interested in design and synthesis of stable chiral metal nanoparticles to use them as reusable catalyst for asymmetric synthesis with very high turnover number.
Synthesis of biologically active molecules:
Our research group is interested in total synthesis of biologically active natural and unnatural products using our own above-mentioned methodologies as key step.