Paul E. Donahue

Platinum catalysed hydrosilylation of alkynes: Comparison of rates of addition of terminal olefins to internal alkynes

The relative rates of platinum catalysed hydrosilytalion of terminal olefins versus internal alkynes were compared in competitive reactions. (EtO)3SiH added almost exclusively (97%) to PhCCPh versus styrene. The reaction of (EtO)3SiH with equimolar amounts of 2-decyne and 1-hexene gave a 78:22 ratio of alkyne products 6/6′ versus alkene product 7. The reaction of (EtO)3SiH with equimolar amounts of styrene and 1-phenyl-1-propyne gave a 78:22 ratio of alkyne products 10/10′ to products 9. The silane, Me3SiOSiMe2H, reacted with equimolar amounts of 2-decyne and 1-hexene to give a 90: 10 ratio of alkyne products 8/8′ to alkene product 9. All of the products had E stereochemistry about the CC double bond as determined by 29Si NMR (3J(Si-H)).

29Si and 13C NMR Studies of organofunctional di- and trisilanes

Abstract A series of di- and trisilanes of general structure Ph3SiSiMe2R and (Ph3Si)2SiR′R″ were synthesized, and the 29Si and 13C chemical shifts and one-bond siliconsilicon coupling constants (1JSiSi) were measured. The coupling constants of the disilanes were found to be primarily dependent upon the inductive effect of the alkyl group, R, as measured by the Taft o★ constant. In both series of compounds, increasing alkyl substitution at silicon led to a decrease in 1JSiSi.