Five-membered Heterocyclic Thiones. Part II. Oxazole-2-thione

Construction of Five-Membered Heterocyclic Compounds via Radical Cyclization

Facile formation of five-membered N-heterocyclic zirconacycloallenoids.

The reaction of η(2)-iminozirconocene chloride complexes with trimethylsilylethynyl lithium leads to rapid C-C coupling at room temperature to yield the corresponding five-membered aza-zirconacycloallenoids. Such compounds were also obtained by trapping of in situ generated zirconocene with alkynyl imines.

Palladium-Catalyzed Amination of Unprotected Five-Membered Heterocyclic Bromides

An efficient method for the palladium-catalyzed amination of unprotected bromoimidazoles and bromopyrazoles is presented. The transformation is facilitated by the use of our newly developed Pd precatalyst based on the bulky biarylphosphine ligand tBuBrettPhos (L4). The mild reaction conditions employed allow for the preparation of a broad scope of aminoimidazoles and aminopyrazoles in moderate ...

Scope and mechanism of palladium-catalyzed amination of five-membered heterocyclic halides.

Detailed studies have been conducted to determine the activity of palladium catalysts for the amination of five-membered heterocyclic halides and to determine the factors that control the scope of this reaction. Palladium-catalyzed aminations of the electron-rich furanyl, thiophenyl, and indolyl halides and of the related 2-halogenated thiazoles, benzimidazole, and benzoxazole have been shown t...

Proton Affinity of Five-Membered Heterocyclic Amines: Assessment of Computational Procedures

Ab initio quantum chemical calculations, G3B3, second-order Møller– Plesset (MP2), and the hybrid density functional method B3LYP were employed to compute the proton affinities of 24 heterocyclic amines. A range of basis sets are employed, starting from doublepolarization quality to triplequality basis set with augmented diffuse and polarization function. Experimental values were used to calibr...