Allylsilanes in organic synthesis homoallylic alcohol synthesis and electrophilic alkylation

The chelating effect on regio- and stereochemical control of the homoallyl alcohol synthesis and electrophilic substitution of allylsilane was studied, using 2,2-dimethyl-1-$ {$1- ((S)-2-(2-methoxyethoxy)methyl) pyrrolidinyl$ }$-2-sila-4-pentene (S1) and 2,2-Dimethyl-1-$ {$1- ((S)-2-hydroxymethyl) pyrrolidinyl$ !$-2-sila-4-pentene (S2), with S1 synthesized from L-Prolinol.The synthesis of homoallyl alcohol was carried out by allyl transformation from S1 and S2 to a Lewis acid activated aldehyde. Chelation between the allylsilyl ligand and the Lewis acid:aldehyde complex was found to favor the cyclic syn-clinal over the acyclic anti-periplanar transition state, in the asymmetric synthesis of the alcohol 1-dodecen-4-ol (P1). The bulky, remote and weak chelating ligand resulted in only modest selectivity and average chemical yield.Regio- and stereochemical control of the electrophilic alkylation of allylsilanes S1 were achieved due to chelating effect that favored $ alpha$-alkylation. The chiral chelating ligand also resulted in enhanced stereochemical control electrophilic alkylation. Steric effect, due to a large electrophile, and solvent effect that causes disruption of the chelated complex, decrease $ alpha$-selectivity