Grignard reagents reaction with allylic amines

Whereas THF and DME were suitable solvents, Lewis basic additives such as HMPA, DMSO or TMEDA hampered the reaction.82 These results point towards an intramolecular assistance of the zinc coordinated by the nitrogen atom. A related effect was evidenced in the additions of Grignard reagents to allylic alcohols83-87. Two mechanisms were proposed for the allylzincation of homoallylic amines involving formation of a complex with the... 

The most conspicuous property of aliphatic amines, apart from their fishy smell, is their high basicity, which usually precludes N-alkylations under acidic reaction conditions (last reaction, Scheme 6.3). Hence, alkylation of amines with tertiary alkyl groups is not usually possible without the use of highly stabilized carbocations which can be formed under basic reaction conditions. Rare exceptions are N-alkyla-tions of amines via radicals (Scheme 4.2), copper-catalyzed propargylations (Scheme 6.3), and the addition of amines to some Michael acceptors and allyl palladium or iridium complexes. Better strategies for the preparation of tert-alkylamines include the addition of Grignard reagents to ketone-derived imines [13] or the reduction of tert-alkyl nitro compounds. 

The allylation of imines with allylindium reagents in organic solvents gives the corresponding homoallylic amines.251-253 Under solvent-free conditions, the indium-mediated reaction of iV-benzylideneaniline furnishes a mixture of mono-allylated 79 and bis-allylated products 80 (Equation (56)). The bis-allylated product 80 presumably arises via a formation of an iminium salt, which is subsequently attacked by the allylindium nucleophiles. Formation of 80 is entirely suppressed by addition of allyl bromide to indium metal prior to any addition of the imine (Grignard-type reaction).254... 

---