Allylation of Carbon-Nitrogen Double Bonds

The Hosomi-Sakurai reaction of in situ-generated iminium salts were extensively 

Dual activation of allylsilanes and imines by fluoride ion and a Lewis acid also 

Allyltriorganosilanes react with activated C-N double bonds such as iminium salts and Lewis acid-coordinated imines at the y-position to give homoallylamines.14,118 For example, in the presence of BF3, iV-acylimines generated in situ by the reaction of aldehydes or acetals with carbamates are efficiently allylated with allyltrimethylsilanes (Equation (26)).119,119a,12° The use of homochiral crotylsilanes such as 20 leads to highly diastereo- and enantioselective synthesis of homoallylamines (Equation (27)). a Allenylation of the iV-acylimines can be performed with propargylsi lanes. 

Intramolecular allylation of imines with allylsilanes is useful for the synthesis of substituted piperidines.123 

The allylation of a-iV-tosylimino esters, highly activated imines, proceeds by catalytic use of a Lewis acid. Tol-BINAP-Cu(l) complexes are effective catalysts of asymmetric allylation of these imines with allylsilanes (Equation (28)).124 125 The presence of an aryl group at the position j3 to silicon improves the enantioselectivity. 

A catalytic amount of TBAF is effective in the allylation of aromatic imines with 10 in refluxing THF. Similar to the TBAF-catalyzed carbonyl allylation, the imine allylation is promoted by a fluoride-triggered autocatalytic cycle. 

The 7t-allylpalladium-TBAF co-catalyst system described in Equation (20) enables the allylation of aromatic imines as well as aldehydes at room temperature.93 Chiral 7t-allylpalladium complex 21 is an efficient asymmetric catalyst of the imine allylation (Equation (29)).93 126 

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