Quinoline-Proline,Triazole Hybrids: Design,Synthesis, Antituberculosis,Molecular Docking,and ADMET Studies

A series of novel quinoline-proline hybrids ( 11a-g ) and quinoline-proline-1,2,3-triazole hybrids ( 12-14 ) were synthesized by click chemistry based on molecular hybridization concept and were characterized by NMR, mass spectrometry, and elemental analysis. All the titled target compounds were tested for antitubercular activity by MABA and LORA methods by in vitro. Interestingly, two compounds (2R,4S)-1-((2-cyclopropyl-4-(4-fluorophenyl)-quinolin-3-yl)-methyl)-4-(4-nitrobenzamido)-N-phenylpyrrolidine-2-carboxamide ( 11b ) and (2R,4S)-1-((2-cyclopropyl-4-(4-fluorophenyl)-quinolin-3-yl)-methyl)-4-(4-fluorobenzamido)-N-phenylpyrrolidine-2-carboxamide ( 11c ) exhibited significant activity against the tested Mycobacterium tuberculosis H37Rv strain. Further, the cytotoxicity ( CC ₅₀ ) profile of the titled compounds against the Vero cell was performed and discussed. A molecular docking study of the hit compounds ( 11b and 11c ) was also performed to find their putative binding interaction with the active site of the target proteins. Finally, in silico ADMET properties were also predicted for all the synthesized molecules to evaluate their drug-likeness behavior.     

Regioselective synthesis of spiro isoxazole-oxindole-tetrahydrothiophene hybrids via cascade reactions under catalyst-free conditions

Catalyst-free synthesis of the isoxazole-spirooxindole-tetrahydrothiophene hybrids is reported. Formation of 1,4-thia-Michael and intramolecular aldol reactions were observed (instead of 1,6-thia-Michael followed by vinylogous Henry reactions) in a regioselective fashion to give new isoxazole-spirooxindole-tetrahydrothiophene hybrids with excellent yields.     

New chemical and chemo-enzymatic routes for the synthesis of (RS)- and (S)-enciprazine

The chemo-enzymatic synthesis of racemic and enantiopure (RS)- and (S)-enciprazine 1, a non-benzodiazepine anxiolytic drug, is described herein. The synthesis started from 1-(2-methoxyphenyl) piperazine 3, which was treated with 2-(chloromethyl) oxirane (RS)-4 using lithium bromide to afford a racemic alcohol, 1-chloro-3-(4-(2-methoxyphenyl) piperazin-1-yl) propan-2-ol (RS)-6 in 85% yield. Intermediate (S)-6 was synthesized from racemic alcohol (RS)-6 using Candida rugosa lipase (CRL) with vinyl acetate as the acyl donor. Various reaction parameters such as temperature, time, substrate, enzyme concentration, and the effect of the reaction medium on the conversion and enantiomeric excess for the transesterification of (RS)-6 by CRL were optimized. It was observed that 10 mM of (RS)-6, 50 mg/mL of CRL in 4.0 mL of toluene with vinyl acetate (5.4 mmol) as acyl donor at 30 °C gave good conversion (C = 49.4%) and enantiomeric excess (ee_P = 98.4% and ee_S = 96%) after 9 h of reaction. Compound (S)-6 is a key intermediate for the synthesis of enantiopure (S)-1. The (RS)- and (S)-enciprazine drug 1 was synthesized by treating (RS)- and (S)-6 with 3,4,5-trimethoxyphenol 5 using MeCN as a solvent and K₂CO₃ as a base.     

Synthesis of functionalized chromene and spirochromenes using l-proline-melamine as highly efficient and recyclable homogeneous catalyst at room temperature

An efficient and recyclable homogeneous catalyst is developed using commercially cheap l-proline and melamine for the synthesis of chromenes and spirochromenes (spirooxindoles) via multicomponent reactions at room temperature. Systematic studies were conducted in order to achieve desired reactivity and recyclability of the catalyst using various α-amino acids and aromatic amines as donor-acceptor pairs. Among the screened combinations, l-proline and melamine (3:1 ratio; 3 mol% on total weight) was found to be best catalyst to give the desired products with excellent yields (up to 99%) in very short times (1–15 min) at room temperature in DMSO as solvent. The catalyst was recovered by adding EtOAc and reused up to 5 cycles without losing the catalytic activity.     

Design,synthesis and biological evaluation of novel N1,N8-bis(((4-((5-aryl-1,3,4-oxadiazol-2-yl)methoxy)phenyl)amino)oxy)-1-naphthamide derivatives

A new series of 1,8-bis(4-((5-phenyl-1,3,4-oxadiazol-2-yl) methoxy)-substituted aryl) naphthalene-1,8-dicarboxamide derivatives (6a–j) were synthesized in the presence of POCl₃ and obtained good yields. All the synthesized novel compounds were characterized by IR, ¹H NMR, ¹³C NMR, HRMS spectroscopic data and elemental analysis. All the synthesized compounds evaluated for their antibacterial and antifungal activities. The antibacterial activity screened against Gram-positive bacteria Staphylococcus aureus and Gram-negative bacteria Escherichia coli and used standard reference drug ciprofloxacin. The antifungal activity screened against two pathogenic fungal strains Aspergillus niger and Candida albicans used a reference standard drug Voriconazole. All these compounds (6a–j) demonstrate good antibacterial and antifungal activity. Among them, compounds 6h and 6c show highest antibacterial and antifungal activity.     

Design,synthesis, biological evaluation and in silico molecular docking studies of novel benzochromeno[2,3-d]thiazolopyrimidine derivatives

Research on Chemical Intermediates - A new series of benzochromeno[2,3-d]thiazolopyrimidine derivatives were synthesized by involving...