Asymmetric Synthesis of Multi-Substituted Tetrahydrofurans via Palladium/Rhodium Synergistic Catalyzed [3+2] Decarboxylative Cycloaddition of Vinylethylene Carbonates.

Unlike the comprehensive development of tandem multi-metallic catalysis, bimetallic synergistic catalysis has been challenging to achieve high stereoselectivity with the generation of multi-stereogenic centers. Herein, an efficient synergistic catalysis for the diastereo- and enantioselective synthesis of multi-substituted tetrahydrofuran derivatives has been developed. Under mild reaction conditions, a series of target molecules with three consecutive stereocenters were synthesized by a palladium(0)/rhodium(III) bimetal-catalyzed asymmetric decarboxylative [3+2]-cycloaddition of vinylethylene carbonates with α,ß-unsaturated carbonyl compounds. The corresponding adducts were obtained with moderate to high yields (67 %∼98 %) and excellent stereoselectivities (>20 : 1 d.r., up to 99 % ee).

Synthesis of novel nicotinamide susbstituted phthalocyanine and photodynamic antomicrobial chemotherapy evaluation potentiated by potassium iodide against the gram positive S. aureus and gram negative E. coli.

In the present work, we propose the synthesis of novel nicotinamide subsituted phthlocyanine photosensitizer (PS) and characterized by FTIR, UV-visible, H-NMR and MALDI Toff spectroscopy. Nicotinamide plays a vital rule in the central nervous system and its potential as a therapeutic for neurodegenerative disease. Nicotinamide substituted PS (3) efficiently produced ROS via type-1 process as measured by DCF assay. We observed that our PS after red light illumination (22 J/cm2) killed gram positive S. aureus upto 3 log reduction. Furher the addition of Potassium Iodide (100 mM) significantly potentiated PS at lower concentrations and enhanced the bacterial killing upto 6 log reduction against the S. aureus. We further found that the synergistic effect of PS and KI also eradicated the gram negative E. coli strain at lower concentraion of PS and found to killed E. coli upto 5 log reduction under the red light illumination at 22 J/cm2 of light dose. The conjugation of such biologically important form of vitamin B3 with PS would be a great addition and could pav the way for the novel photodynamic agent in the treatement of cancer and infectious diseases. A new symmetrical Nicotinamide tetrasubstituted zinc phthalocyanine (3) was synthesized. Upon addition of potassium Iodide with PS, the PS exhibited significant photodynamic activity with 5-6 logs reduction in bacterial load was achieved.

Enantioselective synthesis of tetrahydroisoquinoline derivatives via chiral-at-metal rhodium complex catalyzed [3+2] cycloaddition.

An asymmetric [3+2] cycloaddition of C,N-cyclic azomethine imines with α,ß-unsaturated 2-acyl imidazoles catalyzed by a chiral-at-metal rhodium complex has been developed. The corresponding C-1-substituted tetrahydroisoquinoline derivatives were obtained in high yields (>90%) with excellent stereoselectivities (up to 99% ee and >20 : 1 dr). The reaction can be conducted on a gram-scale using a low catalyst loading (0.5 mol%) with high yield and selectivity.

Synthesis, in vitro α-glucosidase inhibitory activity and molecular docking studies of new thiazole derivatives.

Current study based on the synthesis of new thiazole derivatives via "one pot" multicomponent reaction, evaluation of their in vitro α-glucosidase inhibitory activities, and in silico studies. All synthetic compounds were fully characterized by (1)H NMR, (13)C NMR and EIMS. CHN analysis was also performed. These newly synthesized compounds showed activities in the range of IC50=9.06±0.10-82.50±1.70µM as compared to standard acarbose (IC50=38.25±0.12µM). It is worth mentioning that most of the compounds such as 1 (IC50=23.60±0.39µM), 2 (IC50=22.70±0.60µM), 3 (IC50=22.40±0.32µM), 4 (IC50=26.5±0.40µM), 6 (IC50=34.60±0.60µM), 7 (IC50=26.20±0.43µM), 8 (IC50=14.06±0.18µM), 9 (IC50=17.60±0.28µM), 10 (IC50=27.16±0.41µM), 11 (IC50=19.16±0.19µM), 12 (IC50=9.06±0.10µM), 13 (IC50=12.80±0.21µM), 14 (IC50=11.94±0.18µM), 15 (IC50=16.90±0.20µM), 16 (IC50=12.60±0.14µM), 17 (IC50=16.30±0.29µM), and 18 (IC50=32.60±0.61µM) exhibited potent inhibitory potential. Molecular docking study was performed in order to understand the molecular interactions between the molecule and enzyme. Newly identified α-glucosidase inhibitors except few were found to be completely non-toxic.