Heck reaction allylsilanes

Scheme 6/1.3. Allylsilane-terminated domino Heck reactions of 6/1-14a-f.

Use of the allylsilanes as the alkene components in the Heck reaction is illustrated in the palladium catalyzed y-allylation of organic halides or triflate or acetate176. The... 

Scheme 6. Allylsilane-terminated cascade Heck reaction by Tietze et al.

In probing the relative reactivities of alkynes and alkenes, a preference for the addition to the triple bond has been observed (e.g.. Scheme 3-18 below) [54]. When allylsilanes such as 10 are cyclized by an intramolecular Heck reaction, elimination directed towards the silicon residue can occur to give the desilylated 12 as well as the silylsubstituted 11 (Scheme 3-5) [61a]. 

Cyclizations. A great number of substrates designed for cyclization have been studied, including those leading to l-sulfinylmethylene-2-methylenecycloalkanes and to pyrroles. - Intramolecular Heck reaction involving enol triflate and allylsilane moieties is useful for the synthesis of cyclic compounds. ... 

An intramolecular reductive Heck reaction in the presence of HCOONa is useful for the access to exocyclic allylsilanes. ... 

Scheme 12.19 Allylsilane terminated enantioselective intramolecular Mizoroki-Heck reactions.

Use of the allylsilanes as the alkene components in the Heck reaction is illustrated in the regioselective intramolecular cyclization of 120 (equation 98) °. In addition, a high enantioselectivity of 90 %ee is obtained when the chiral phosphine (S )-BINAP is employed. The propargylsilane analog undergoes a similar reaction ... 

Because many 4-benzylpiperidines are physiologically and pharmacologically active, an efficient route to these compounds was developed <03TL8249>. Cyclization of imines containing an allylsilane with aldehydes in a one-pot reaction resulted in 4-methylenepiperidines in good yields. Heck-type arylation of arylboronic acids with 4-methylenepiperidines afforded the styryl derivatives, which gave the desired piperidines on reduction. 

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