Synthesis of novel chiral monomers by means of Umani‐Ronchi–Savoia allylation and their polymerization

Umani‐Ronchi–Savoia allylation is one of the most successful and useful methods for the preparation of optically pure secondary amines bearing two stereogenic centers at both α‐positions. We have prepared novel chiral amine monomers by means of this methodology as a key step of the synthesis. Diastereoselective allylation of chiral imines (3–5) derived from (S)‐valine gave optically pure secondary amines 6. Hydrogenation of the allylic group followed by introduction of a polymerizable 4‐vinylphenyl group led to enantiopure monomer 9. Prenylzinc reagents were also found to react with the imines to yield the corresponding optically pure amines 7. Since prenyl addition product does not inhibit the radical polymerization, chiral monomers 7b, 7d could be prepared directly by prenylzinc addition to imine having a polymerizable group. These chiral monomers were easily polymerized with styrene under radical polymerization conditions.