title: [2+2+2] cyclotrimerization of alkynes and isocyanates/isothiocyanates catalyzed by ruthenium-alkylidene complexes.
abstract: Ruthenium carbene catalysts are able to catalyze crossed [2+2+2] cyclotrimerizations of α,ω-diynes with isocyanates, isothiocyanates, and carbon disulfide. Both aliphatic and aromatic isocyanates can be used to produce fused 2-pyridones, although aliphatic isocyanates were more reactive. Aromatic isocyanates give better results when they bear electron-donating substituents. The reaction of unsymmetrical α,ω-diynes gave a product only with the substituent adjacent to the 2-pyridone nitrogen. Isothiocyanates gave thiopyranimines upon reaction with the C═S bond, whereas CS2 reacted efficiently to give a thioxothiopyrane.
authors.affiliation: Facultad de Farmacia, Dpto. Química y Bioquímica, Universidad San Pablo CEU , Urb. Montepríncipe, ctra. Boadilla km 5,300, Boadilla del Monte, 28668 Madrid, Spain.
authors.forename: Silvia
authors.initials: S
authors.lastname: Alvarez
authors.forename: Sandra
authors.initials: S
authors.lastname: Medina
authors.forename: Gema
authors.initials: G
authors.lastname: Domínguez
authors.forename: Javier
authors.initials: J
authors.lastname: Pérez-Castells
mesh_terms: D000480:Alkynes / Q000737:chemistry*; D002384:Catalysis; D056831:Coordination Complexes / Q000737:chemistry*; D003500:Cyclization; D003516:Cycloparaffins / Q000737:chemistry*; D017953:Isocyanates / Q000737:chemistry*; D017879:Isothiocyanates / Q000737:chemistry*; D012428:Ruthenium; D013237:Stereoisomerism
chemical_list: D000480:Alkynes; D056831:Coordination Complexes; D003516:Cycloparaffins; D017953:Isocyanates; D017879:Isothiocyanates; C037152:isothiocyanic acid; D012428:Ruthenium