Modulation of Silver-Titania Nanoparticles on Polymethylhydrosiloxane-based Semi-Interpenetrating Networks for Catalytic Alkynylation of Trifluoromethyl Ketones and Aromatic Aldehydes in Water.

In this work, we have developed a new approach to monodispersed hybrid Ag@TiO₂ nanocomposites using a titanium-promoted cross-linking reduction in the SiH functional material, polymethylhydrosiloxane (PMHS)-based semi-interpenetrating networks (PMHSIPN). The titania was designed to be highly dispersed on the functional material and then the Ag@TiO₂ nanoparticles were formed in uniform size and shape under mild conditions. The experimental results reveal that the nanosilver catalysts (the fabricated Ag@TiO₂ located on the PMHSIPNs, namely, nanoAg@TiO₂@PMHSIPN) have enhanced catalytic activities in the alkynylation of trifluoromethyl ketones or α,β-unsaturated trifluoromethyl ketones with terminal alkynes. In this reaction, the hybrid Ag@TiO₂ nanoparticles exhibited a high level of catalytic activity for the selective 1,2-alkynylation of various trifluoromethyl ketones and α,β-unsaturated trifluoromethyl ketones into a wide range of fluorinated alcohols in water. Finally, on the basis of the nanoAg@TiO₂@PMHSIPN-catalyzed alkynylation of trifluoromethyl ketones, we developed a new concept whereby highly reactive substrates act as a 'reactive tractor' or 'reactive springboard' to drive the transformation of poorly reactive substrates as springboard chemistry. Consequently, we found that trifluoromethyl ketone can be used as an efficient additive in the nanosilver-catalyzed alkynylation of aldehydes. [ABSTRACT FROM AUTHOR]