Metal catalyzed asymmetric cyanation reactions

Asymmetric cyanation of activated olefins with ethyl cyanoformate catalyzed by a modular titanium catalyst

Asymmetric cyanation of a class of easily available olefins with a favorable cyanide source ethyl cyanoformate (CNCOOEt) was realized by an interesting modular catalyst. High yields and ee values were obtained for a range of substrates under solvent-free and mild reaction conditions. The products obtained could be easily transformed to the enantioenriched useful intermediates 5, 6, and pharmaceutically important gamma-aminobutyric acid 7.

Stereospecific Suzuki cross-coupling of alkyl alpha-cyanohydrin triflates

Scalemic alpha-cyanohydrin triflates undergo Pd-catalyzed cross-coupling with aryl, heteroaryl, and vinyl boronic acids under mild conditions. Coupling proceeds with complete inversion of configuration at the stereogenic carbon. The resultant nitrile can be easily converted into a variety of alternative functional groups of value in organic synthesis and thus achieves a higher level of molecular complexity than the products of traditional Suzuki reactions.

Ultrasound-mediated synthesis of camphoric acid-based chiral salens for the enantioselective trimethylsilylcyanation of aldehydes

New chiral salen ligands were prepared by the ultrasound-irradiated condensation of optically active (1R, 3S)-1,2,2-trimethyl-1,3-diaminocyclopentane with aromatic 1-hydroxyaldehydes. The ultrasound-mediated process is more convenient due to shorter reaction times, energy economy, and easier isolation of the products. The in situ formed Ti(IV)(salen) complexes, evaluated as catalysts in the enantioselective trimethylsilylcyanation of benzaldehyde, were found to be efficient for this process, originating the corresponding product in high yields (72-99%) and selectivities of up to 79%. The lowest energy transition states were determined by computational studies. These results were in qualitative agreement with the experimentally observed ones.

Synthesis, characterization, DNA binding and cleavage studies of chiral Ru(II) salen complexes

Interaction of chiral Ru(II) salen complexes (S)-1 and (R)-1 with Calf Thymus DNA (CT-DNA) was studied by absorption spectroscopy, competitive binding study, viscosity measurements, CD measurements, thermal denaturation study and cleavage studies by agarose gel electrophoresis. The DNA binding affinity of (S)-1 (6.25 x 10(3)M(-1)) was found to be greater than (R)-1 (3.0 x 10(3)M(-1)). The antimicrobial studies of these complexes on five different gram (+)/(-) bacteria and three different fungal organisms showed selective inhibition of the growth of gram (+) bacteria and were not affective against gram (-) and fungal organisms. Further, the (S)-1 enantiomer inhibited the growth of organisms to a greater extent as compared to (R)-1 enantiomer.