ASYMMETRIC ALLYLATION REACTIONS USING CHIRAL TIN COMPLEXES

JOANNE L. STEWART

The most important chemical challenge in the pharmaceutical industry today is the synthesis of single enantiomers. A pair of enantiomers consists of a molecule and its mirror image. Often, the two nearly identical molecules exhibit very different biological activity. In fact, in the case of drugs, one enantiomer may prove very helpful while its mirror image may be harmful. A typical organic synthesis leads to a 50/50 mixture of enantiomers, or a racemic mixture, so making only one enantiomer without making its mirror image is a tremendous synthetic challenge.

My research group is making new main group metal compounds that may be used in the synthesis of single enantiomers. This process is called asymmetric synthesis. The main group metal compounds we are studying may be used in a variety of chemical transformations. We have begun our studies by using them to carry out a class of reactions called allylation reactions. The addition of an allyl group to an aldehyde leads to a homoallylic alcohol.

Homoallylic alcohols are versatile building blocks to other molecules.

Racemic homoallylic alcohols may be synthesized starting with the tin(II) complex Sn[N(SiMe₃)₂]₂.

J. Auge, G. Bourleaux, J. Organomet. Chem., 1989, 377, 205-210.

We propose to make the alcohol enantioselectively by using a chiral ligand (L*) on the tin(II) complex.

The chiral ligands we are investigating include alcohols (1), sulfonamides (2), and silylamines (3).