Allyl chloride, hydrosilation

Until relatively recently, less attention has been given to catalysis of redistribution reactions by transition metal complexes. Redistributions have been observed during the course of platinum-catalyzed hydrosila-tion hence, the scrambling reaction can be a nuisance by decreasing the yield of desired hydrosilation products. A noteworthy example is the H/Cl exchange that occurs during the hydrosilation of allyl chloride [Eq. (10)]. 

Alkenes with a variety of substituents such as acetal, amine, amide, carbamate, ester, ether, isocyanate, ketone, oxirane, and snlfide can be hydrosilated, usually without affecting the ftinctional group. However, this is not always fine for example, allyl chloride gives a considerable amount of the reduction product (see equation 26). Table 4 lists representative examples of hydrosilation. It is not so remarkable in the case of radical hydrosilation, but reactivity is high for hydrosUane, which has electronegative group in the case of transition metal catalyzed hydrosilation. 

To illustrate the serious problem, a case in point is the hydrosilation of allyl chloride which produces equimolar quantities of propene and a chlorosilane as the primary byproducts [Eq. (37)]. The propene can undergo hydrosilation itself leading to a secondary byproduct. Some of the best yields of 3-chloropropylsilane lie in the range 70-80% with a few combinations of hydrosilane and catalyst, but for many useful hydrosilanes, the primary byproducts can be 60% or higher. 

We have previously reported on the synthesis of a series of mono- and bifunctional poly(DMS) having a variety of reactive end groups, such as silan (Si-H), vinyl, hydroxyalkyl, dimethylamino and carboxyllic acid groups.7 We have also described already on telechelic poly(DMS) having tosylate end group, lb and l b, where the hydrosilation reaction of poly(DMS) having silan end group was performed with allyl alcohol in the presence of Pt/C catalyst, followed by the tosylation reaction with tosyl chloride in the presence of dimethylaminopyridine.9... 

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