Five-membered Heterocyclic Thiones. Part III. 1,2,5-Thiadiazole-3-thiones

Synthesis of 3,3-disubstituted indoline-2-thiones catalysed by an N-heterocyclic carbene.

A catalytic method has been developed for construction of indoline-2-thiones containing an all-carbon quaternary centre at the C-3 position. Successive treatment of α,β-unsaturated aldehydes bearing an isothiocyanato moiety with an in situ generated N-heterocyclic carbene and an appropriate heteroatomic nucleophile provided the 3,3-disubstituted indoline derivatives in moderate to good yields.

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 ...

Ones, thiones, and N-oxides: an exercise in imidazole chemistry.

General Procedure: 1-Propylimidazole-N-oxide (2a) 1 (1.0 g, 4.1 mmol) and 1,3,5-tripropylhexahydro-1,3,5triazine (0.5 g, 2.4 mmol) were dissolved in ethanol (20 mL). The reaction mixture was heated to reflux for 10 h. The light brown solution was cooled to room temperature and the solvent removed under reduced pressure. The oily residue solidified upon trituration with diethylether to give 2a a...