Hydrosilylation of 2-(2-Propynyl)-2,3-dihydro-1,2-benzothiazol-3-one 1,1-Dioxide with 1-Alkynyl(dimethyl)- and Bis(1-alkynyl)methylsilanes

Hydrosilylation of 2-(2-propynyl)-2,3-dihydro-1,2-benzothiazol-3-one 1,1-dioxide with 1-alkynyldimethyl- and bis(1-alkynyl)methylsilanes of the general formula Me _n HSi(C=-CR)₃-n (n = 1, 2) in the presence of H₂PtCl₆ (Speier's catalyst) occurs in a nonregioselective but stereoselective fashion, yielding mixtures of the corresponding trans-- and -adducts. The fraction of the latter ranges from 50 to 70%, depending mainly on the substrate nature rather than on the nature of substituent at the triple bond of the reagent.     

α-Acetylene Hydrosilanes as Hydrosilylating Agents for Terminal Arylacetylenes

The hydrosilylation of a number of acetylenes RCCH (R, R' = Ph, CH₂OPh, CH₂SPh) with -ethynylhydrosilanes Me₂SiHCHCR' in the presence of H₂PtCl₆ was investigated. The addition did not occur regioselectively, but was stereospecific and afforded a mixture of - and trans--adducts. The replacement of phenyl substituent by phenoxymethyl both in the molecule of ethynylsilane and the acetylene substrate resulted in growing proportion of the -adduct in the reaction mixture up to 10-60%.