Novel Synthesis of 3‐Substituted 2‐Thiohydantoins via Aza‐Wittig Reaction on Poly(ethylene Glycol)

Chiral Brønsted acid-catalyzed enantioselective Friedel-Crafts reaction of 2-methoxyfuran with aliphatic ketimines generated in situ

An enantioselective Friedel-Crafts reaction with aliphatic ketimines generated in situ from hemiaminal ethers catalyzed by a chiral Brønsted acid was investigated. The reaction of 2-methoxyfuran with (thio)hydantoin-derived hemiaminal methyl ether proceeded under the influence of a chiral phosphoric acid catalyst to afford the corresponding adduct possessing a quaternary stereogenic center in high yield with high enantioselectivity. Theoretical studies were also conducted to clarify the mechanism of the stereochemical outcome and the major factors contributing to the efficient enantioselection.

Pharmaceutical importance and synthetic strategies for imidazolidine-2-thione and imidazole-2-thione derivatives

Imidazole heterocycles containing oxygen or sulfur heteroatoms are of considerable pharmaceutical interest. Many synthetic strategies for imidazolidine-2-thione and imidazole-2-thione derivatives were developed in the past years. They have been well documented by a steadily increasing number of publications and patents. Substituted imidazolidine-2-thiones and imidazole-2-thiones display remarkable biological activities. For instance, imidazole-2-thione has been reported to exhibit antimicrobial, antifungal, antithyroid, antioxidant, cardiotonic, antihypertensive, Dopamine beta-Hydroxylase (DBH) inhibitory and anti-HIV properties. Imidazolidine-2-thione derivatives have been reported to exhibit antimicrobial activity, anti-HIV activity, antifungal activity and so forth. The main purpose of this review is to present a survey of the literature on the different methods of synthesis and reactions involving imidazolidine-2-thione and imidazole-2-thione during the last few decades. This article summarizes an efficient, microwave-assisted method for the liquid-phase combinatorial synthesis of 3,5-disubstituted-thiohydantoin, also reported previously. Synthesis of metal complexes of imidazolidine-2-thione and its derivatives were reported as antimicrobial agents also discussed in the article. Some of the chiral imidazolidine-2-thione N-and C-nucleoside were reported as precursors for the synthesis of azidonucleosides and fluoronucleosides known for their anti-AIDS activity. Metal complexes of heterocyclic thione ligands were reported to possess antifungal activity. Imidazolidine-2-thione and imidazole-2-thione derivatives have found applications in diverse therapeutic areas. Imidazolidine-2-thiones are also used as a chiral auxiliary and ligand for asymmetric catalysis.