Imtiyaz Ahmed M. Khazi

Synthesis and antimicrobial studies of novel methylene bridged benzisoxazolyl imidazo[2,1-b][1,3,4]thiadiazole derivatives.

Novel methylene bridged benzisoxazolyl imidazo[2,1-b][1,3,4]thiadiazoles (3a-f) were synthesized from benzisoxazolyl-3-acetic acid and thiosemicarbazide. Reaction of 3 with bromine in glacial acetic acid in the presence of anhydrous sodium acetate yielded the corresponding 5-bromo derivatives (4a-f). While compound 3 furnished the 5-nitroso derivatives (5a-f) on refluxing with sodium nitrite solution. Thiocyanato derivatives (6a-f) were obtained by treating the imidazothiadiazole 3 with bromine and potassium thiocyanate in glacial acetic acid at room temperature. The structures of the newly synthesized compounds were confirmed by IR, NMR, mass and elemental analysis. All the compounds were screened for their antibacterial and antifungal activities. Some of the compounds displayed very good antibacterial and antifungal activity.

Mannich bases and novel benzothiazole derivatives of imidazo[2,1-b][1,3,4]thiadiazoles and their biological evaluation

A series of 2,6-disubstituted imidazo[2,1-b][1,3,4]thiadiazoles, their new Mannich bases and novel benzothiazole derivatives were synthesized. The structures of all the synthesized compounds were established by analytical and spectral data. All the compounds were screened for their antitubercular activity against Mycobacterium tuberculosis H37Rv using the BACTEC 460 radiometric system and antibacterial activity against E. coli and B. cirrhosis, antifungal activity against A. niger and P. worthmanni. Among the tested compounds Mannich bases 3e, 3f and 4 g and 5-carbaldehyde derivative 6d have shown excellent inhibition (99, 99, 97 and 95%, respectively) against M. tuberculosis. Mannich bases in general have also shown impressive antifungal activity.

Synthesis, characterization and optoelectronic investigations of bithiophene substituted 1,3,4-oxadiazole derivatives as green fluorescent materials

A series of novel unsymmetrical bithiophene substituted oxadiazole derivatives 2(a–e) were designed and synthesised by employing palladium catalysed Suzuki cross coupling reaction. These bipolar molecules consist of bithiophene as an electron donor unit (D) and electron transporting oxadiazole as acceptor unit (A). The structural integrity of all the new compounds was confirmed by 1H NMR, 13C NMR and GC-MS analysis. The photophysical and electrochemical properties have been studied in detail using UV-Vis absorption, fluorescence spectroscopy and CV measurements. All compounds emit intense green fluorescence with good quantum yields. Density functional theory computations have been carried out to understand the structure–property relationship, the computed values are found to be in good agreement with the experimental results. The results demonstrated that the novel bithiophene containing oxadiazole derivatives could play an important role in organic optoelectronics.

Synthesis and antimicrobial activities of some ethyl 2-arylthio-6-arylimidazo[2,1-b]thiazole-3-carboxylates and their sulfones

A series of new 2-arylthio-3-ethoxycarbonyl-6-arylimidazo[2,1-b]thiazoles (4a–4h) and 2-arenesulfonyl-3-ethoxycarbonyl-6-arylimidazo[2,1-b]thiazoles (5a–5h) have been prepared and characterized by analytical and spectral methods. The title compounds 4a–4h and 5a–5h were obtained by the reaction of 2-amino-4-ethoxycarbonyl-5-arylthiothiazoles (2a and 2b)/2-amino-4-ethoxycarbonyl-5-arenesulphonyl-thiazoles (3a and 3b) with various phenacyl bromides in anhydrous ethanol. These newly synthesized compounds (4a–4h and 5a–5h) were screened for their antibacterial activity against Gram-negative bacterium Escherichia coli, Gram-positive bacterium Staphylococcus aureus, and antifungal properties against Aspergillus niger and Candida albicans.

Synthesis, hypoglycaemic, hypolipidemic and PPARγ agonist activities of 5-(2-Alkyl/aryl-6-Arylimidazo[2,1-b][1,3,4]thiadiazol-5-yl)methylene-1,3-thiazolidinediones.

A novel series of 5‐(2‐alkyl/aryl‐6‐arylimidazo[2,1‐b][1,3,4]thiadiazol‐5‐yl)methylene‐1,3‐thiazolidinediones were synthesized as possible PPARγ agonists. The structures of these target molecules were established by spectral and analytical data. All the newly synthesized compounds were screened for their in vivo hypoglycaemic and hypolipidemic activity in male Wistar rats. Further, compounds with good activity were screened for PPARγ agonist activity. Among the screened compounds, 5‐{[2‐Cyclohexyl‐6‐(4‐methoxyphenyl)imidazo[2,1‐b] [1,3,4]thiadiazol‐5‐yl]methylene}‐1,3‐thiazolidine‐2,4‐dione (3i) exhibits promising hypoglycaemic and hypolipidemic activity via potential PPARγ agonist activity.

Synthesis and pharmacological evaluation of novel thienopyrimidine and triazolothienopyrimidine derivatives

Novel tricyclic thienopyrimidines (2, 3, 5, 8) and triazole-fused tetracyclic thienopyrimidines (6a–c and 9a–c) were synthesized from the precursor 2-amino-4,5,6,7-tetrahydro-1-benzothiophene-3-carbonitrile (1). The structures of newly synthesized compounds were established by spectral and analytical data. The title compounds were screened for analgesic, anti-inflammatory, ulcerogenicity index, and antibacterial activities. Test compounds exhibited significant activity, the compounds (6a–c) and (9a–c) showed more potent analgesic activity, and the compounds (6c) and (9c) showed more potent anti-inflammatory activity than the reference standard Diclofenac Sodium. All the synthesized compounds exhibited remarkable antibacterial activity.

Novel Pyridazine Fused Heterocyclic System: A New Route for the Synthesis of 2‐Alkyl/Aryl[1,3,4]Thiadiazole[2′,3′:2,3] Imidazo[4,5‐d]Pyridazin‐8(7H)‐One

Abstract A series of novel imidazo[2,1‐b][1,3,4]thiadiazole fused pyridazinones have been synthesized in moderate yields by the reaction of 2‐alkyl/arylimidazo[2,1‐b] [1,3,4]thiadiazole‐6‐carbohydrazides under Vilsmeier–Haack reaction conditions. This simple methodology has utility for the synthesis of various fused heterocyclic systems.

Junjappa–Ila (JI) Heteroaromatic Annulation: A New General α‐Oxoketene Dithioacetals Mediated Inverse Method for Synthesis of Substituted Benzothiazoles

Abstract 3‐(Methylthio)‐5‐oxo‐2‐(2‐phenyl‐1,3‐thiazol‐4‐yl)‐4,5‐substituted‐pent‐2‐enenitriles 3a–j were obtained in good yields by condensation of (2‐phenyl‐1,3‐thiazol‐4‐yl)‐acetonitrile (1) with various α‐oxoketene dithioacetals 2a–j in the presence of sodium hydride. The intermediates 3a–j underwent smooth cyclization in the presence of PTSA to afford the corresponding benzothiazoles 4a–j in moderate yields.

A practical one-pot synthesis of coumarins in aqueous sodium bicarbonate via intramolecular Wittig reaction at room temperature

An efficient, simple and relatively inexpensive method for the synthesis of coumarins in aqueous sodium bicarbonate at ambient temperature has been developed. It features an intramolecular Wittig reaction of substituted 2-formylphenyl 2-bromoacetate in saturated aqueous sodium bicarbonate. Its advantages include benign reaction conditions, easy work-up and good overall yield with short reaction time. Various substituted coumarins have been synthesized by utilizing this methodology.

Heterocycles derived from dimethyldithioimidocarbonates of thiadiazole and thiazole

A set of imidazolidine, benzimidazole, benzothiazole and benzoxazole derivatives of 1,3,4-thiadiazoles and thiazoles were prepared from corresponding dimethyldithioimidocarbonates by the reaction with various binucleophiles. The structures of the compounds were elucidated and they were screened for antitubercular activity against Mycobacterium tuberculosis H37Rv using the BACTEC 460 radiometric system and antibacterial activity against E. coli and B. cirrhosis, antifungal activity against A. niger and P. worthmanni.