1.3- Dienes, 1-silylformylation

Silylformylation of 1-alkynes proceeds smoothly even in the presence of a base or a protic reagent. This feature makes it possible to design a cascade-type condensation using the resultant 3-silylalkenals as a component in one-pot operation during the silylformylation. Aza-1,3-dienes 303 are formed with sufficient selectivity by the reaction of 1-alkyne, a hydrosilane, primary amine, and GO under the silylformylation conditions (Equation (52)). ... 

It is demonstrated that the formyl group in 35, prepared by silylformylation of 3-methyl-1-pentyne 34, reacts with methylenetriphenylphosphorane to give the corresponding 1,3-diene 307 (Equation (54)). This two-step transformation can be performed in one pot by carrying out the silylformylation in the presence of a stabilized Wittig reagent... 

Addition of hydrosilane to alkenes, dienes and alkynes is called hydrosilylation, or hydrosilation, and is a commercially important process for the production of many organosilicon compounds. As related reactions, silylformylation of alkynes is treated in Section 7.1.2, and the reduction of carbonyl compounds to alcohols by hydrosilylation is treated in Section 10.2. Compared with other hydrometallations discussed so far, hydrosilylation is sluggish and proceeds satisfactorily only in the presence of catalysts [214], Chloroplatinic acid is the most active catalyst and the hydrosilylation of alkenes catalysed by E PtCU is operated commercially [215]. Colloidal Pt is said to be an active catalytic species. Even the internal alkenes 558 can be hydrosilylated in the presence of a Pt catalyst with concomitant isomerization of the double bond from an internal to a terminal position to give terminal silylalkanes 559. The oxidative addition of hydrosilane to form R Si—Pt—H 560 is the first step of the hydrosilylation, and insertion of alkenes to the Pt—H bond gives 561, and the alkylsilane 562 is obtained by reductive elimination. 

Silylformylation of olefins and alkynes can be regarded as the silicon version of hydroformylation. The reaction involves the concomitant introduction of a silyl group, derived from a hydrosilane, and a formyl group derived from insertion of carbon monoxide, thus producing functionalized olefins and dienes, which are useful synthons. ... 

Rh catalyses the hydrosilylation of alkenes and the dehydrogenative silylation of 1,5-dienes and alkynes, and the silylcarbonylation of alkynes to give p-silylacrylaldehydes with exceptional stereocontrol , ketones and enones give silyl enol ethers, 1,3-cyclobutane dione gives 3-hydroxycyclobutanone, and assists in the silylformylation of ethynyl pyirolidone derivatives to give pyrrolizidine alkaloids, and epoxides to give p-siloxy aldehydes, and... 

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