Oxidative Cycloaddition of 1,1,3,3-Tetramethyldisiloxane to Alkynes Catalyzed by Supported Gold Nanoparticles
作者:Ioannis N. Lykakis、Androniki Psyllaki、Manolis Stratakis
DOI:10.1021/ja2045502
日期:2011.7.13
nanoparticles supported on TiO(2) (0.1-1% mol) catalyze at roomtemperature and at extremely mild conditions the unprecedented oxidative cycloaddition of 1,1,3,3-tetramethyldisiloxane to alkynes, forming substituted 2,5-dihydro-1,2,5-oxadisiloles, with concomitant evolution of hydrogen gas. For the majority of the substrates, the yields are exceptional (up to 99%). The reaction proceeds at room temperature
Gold-Catalyzed Dehydrogenative Cycloaddition of Tethered 1,<i>n</i>-Dihydrodisilanes to Alkynes
作者:Vasiliki Kotzabasaki、Ioannis N. Lykakis、Charis Gryparis、Androniki Psyllaki、Eleni Vasilikogiannaki、Manolis Stratakis
DOI:10.1021/om3011678
日期:2013.1.28
5-hexamethyltrisiloxane (4), and 1,2-bis(dimethylsilyl)benzene (5), to alkynes, forming cycloadducts and releasing H2. Under the same conditions, polymeric methylhydrosiloxane is completely unreactive. For the majority of terminal alkynes and 1,n-dihydrodisilanes the yields are excellent (up to 99%). In general, terminal alkynes are more reactive as compared to internal. The reaction tolerates several
1,omega-Bis[8-(dimethylamino)-1-naphthyl]-1,omega-difluorotrisilane 1 (omega = 3) and tetrasilane 2 (omega = 4) have been prepared. The X-ray crystallography of dl-1 and meso-1 shows unsymmetrical structures having different coordination modes at the two terminal silicons. The unsymmetrical nature of the structure of 1 can also be observed by solid state CP/MAS NMR spectroscopy. Trisilane 1 is thermochemically labile and undergoes facile degradation at 145 degrees C, but is photochemically stable under irradiation of its benzene solution with a 6 W-low pressure mercury lamp, making a sharp contrast to the behavior of their tetracoordinate counterparts containing naphthyl groups which are thermochemically stable but photochemically active. Tetrasilane 2 undergoes a Pd(0)-catalyzed alpha-elimination of a fluorosilane moiety at the two pseudo-pentacoordinated silicon atoms to form the 1,2-difluorodisilane, which is trapped with diphenylacetylene as a double-silylation product. (C) 1999 Elsevier Science S.A. All rights reserved.
Callas,R.; Dunogues,J., Comptes Rendus des Seances de l'Academie des Sciences, Serie C: Sciences Chimiques, 1971, vol. 272, p. 554 - 557