An efficient route for synthesis of 5,6‐diphenylimidazo‐[2,1‐b]thiazoles as antibacterial agents

Abstract

The reaction of 4,5‐diphenylimidazol‐2‐thione (1) with aromatic ketones 2a‐i using the acidified acetic acid method afforded the 4,5‐diphenyl(2‐imidazolylthio)acetophenones 3a‐h in good yields. While, the cyclized product 4i was obtained directly upon reaction of 1 with α‐acetyl naphthalene. Compounds 3a‐h were cyclized directly to the corresponding 3‐aryl‐5,6‐diphenylimidazo[2,1‐b]thiazoles (4a‐c) and (4e‐h). In the same manner the reaction of 1 with aliphatic and/or alicyclic ketones gave the 3‐(4,5‐diphenyl‐2‐imidazolylthio)acetone derivatives 5a‐d, 2‐(4,5‐diphenylimidazolylthio)cycloalkanones 8a,d and the tricyclic compounds 9b‐c respectively. The cyclized compounds 6a‐d and 9a,d were obtained by cyclization of 5a‐d and 8a,b respectively. Oxidation of 1 gives the corresponding bis(4,5‐diphenyl‐2‐imidazolyl)‐disulfide (10) in 90% yield. Some of the synthesized compounds were tested for antifungal and antibacterial activity.

Synthesis and in vitro antiplatelet aggregation screening of novel fluorinated diethyl-2-(benzylthio)-2,3-dihydro-1H-imidazole-4,5-dicarboxylate derivatives

“…They can be formed from a-bromoketones with substituted hydrazines and potassium thiocyanate (Lagoja et al, 2003), from a-hydroxyketones, thiourea and ammonium thiocyanate (Maduskuie et al, 1995), from benzil and thiourea (Muccioli et al, 2006), from phenylglycine methyl ester with phenyl or alkyl isothiocynate (Muccioli et al, 2006) and from diamines and CS 2 over a zinc oxide/aluminium oxide catalyst (Ballabeni et al, 1999) to name a few. The imidazole-2-thiones are extremely reactive and can be alkylated and arylated at both sulphur and nitrogen using a variety of reagents (Trzhtsinskaya and Abramova, 1991), added to activated double bonds such as 2-cyanoethene (Bagrii and Vasilenko, 1978;Trzhtsinskaya et al, 1992), acetylene (Skvortsova et al, 1974), aliphatic and alicyclic ketones and acetophenones (Hozien et al, 2000).…”

Synthesis, reactions, and biological activity of 4,5-diarylimidazole-2-thiones (Review)

“…The reaction of thione 1 with aromatic ketones using acetic acid afforded (4,5-diphenyl-2-imidazolylthio)acetophenones 118 in good yields [86]. At the same time, the reaction with α-acetylnaphthalene gave directly cyclized product 119 [86].…”

“…At the same time, the reaction with α-acetylnaphthalene gave directly cyclized product 119 [86]. In the same manner, the reaction of thione 1 with aliphatic and/or alicyclic ketones (n =1-3) gave 3-(4,5-diphenyl-2-imidazolylthio)acetones 120 and 2-(4,5-diphenylimidazolylthio)cycloalkanones 121 [86]. Oxidation of thione 1 on a Pt electrode in aqueous HCl solution containing ethanol gave the corresponding bis(4,5-diphenyl-2-imidazolyl) disulfide 122 in 90% yield [87,88].…”

“…Cyanoethylation of imidazolethione 1 in pyridine and water gave 3-(2-cyanoethyl)-2-mercaptoimidazole (86). Cyclization of the latter with AcOH/HCl gave imidazo[2,1-b]thiazine 87.…”

“…The reaction of thione 1 with aromatic ketones using acetic acid afforded (4,5-diphenyl-2-imidazolylthio)acetophenones 118 in good yields [86]. At the same time, the reaction with α-acetylnaphthalene gave directly cyclized product 119 [86]. In the same manner, the reaction of thione 1 with aliphatic and/or alicyclic ketones (n =1-3) gave 3-(4,5-diphenyl-2-imidazolylthio)acetones 120 and 2-(4,5-diphenylimidazolylthio)cycloalkanones 121 [86].…”