Synthesis and Chemistry of Some New 2-Mercaptoimidazole Derivatives of Possible Antimicrobial Activity

Synthesis of functionalized imidazolidine-2-thiones via NHC/base-promoted aza-benzoin/aza-acetalization domino reactions

“…Finally, bearing in mind the biological value of imidazole-2thione derivatives, 29,31,32 we embarked on the synthetic elaboration of the imidazolidine-2-thione 5aab previously prepared on the gram-scale (Scheme 7). Accordingly, sequential dehydration (H 2 SO 4 , DMF, reflux, 1 h) and alkylation (BnBr, K 2 CO 3 , DMF, RT) gave access to compound 18 in quantitative yield without the need for intermediate 17 purification.…”

“…25 As a further extension of our interest in the development of NHC-catalyzed umpolung reactions, we herein introduce a novel class of acyl anion acceptors, namely benzylidenethioureas I, and we demonstrate their synthetic potential in domino processes by reporting on the synthesis of the 5-hydroxyimidazolidine-2-thione scaffold II displaying two contiguous stereocenters and a challenging all-substituted carbon site (Scheme 1). 26,27 Imidazolidine-2-thiones and the corresponding imidazole-2-thione analogs are special classes of biologically relevant thiourea derivatives 28 endowed with antithyroid, 29 antitumor, 30 antimicrobial, 31 and dopamine inhibition activities. 32 In spite of their relevance, the preparation of imidazole/imidazolidine-2-thiones is so far troublesome.…”

ChemInform Abstract: Divergent Multicomponent Tandem Palladium‐Catalyzed Aminocarbonylation‐Cyclization Approaches to Functionalized Imidazothiazinones and Imidazothiazoles.

“…Both imidazothiazinonea nd imidazothiazole derivatives are heterocycles of particulari nterest in view of their important biological activity. [12,13] The catalytic processes reported here disclose new and particularly convenient entries to the direct synthesis of functionalized imidazothiazinones and imidazothiazoles that startf rom simple building blocks in am ulticomponent fashion.…”

A Four‐Component Domino Reaction: An Eco‐Compatible Access to Diversified Imidazo[2,1‐b][1,3]thiazin‐5‐ones

“…To date, the common synthetic methods to access imidazo [2,1-b] [1,3]thiazin-5-one scaffolds involve reactions between substituted phenylacryloyl chloride and 2-mercaptoimidazole; [4] bromopropionic acid with substituted imidazo[2,1-b]thiazol-3ones under acetic anhydride/acetic acid heated at reflux; [5] intramolecular cyclization of the respectivet hioacids in the presence of pyridine/acetic anhydride; [6] reactionso fa cryloyl chloride with 2-mercapto-benzimidazole; [7] reaction of isothiocyanate derivatives with corresponding amines; [3c, 8] and reaction of 2 H-pyran-2-ones with imidazolidin-2-thione. [9] The above methods suffer from the use of corrosiver eagents, poor yields, multistep syntheses, and harsh reactionc onditions.…”