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The polymeric ligand can be recovered and reused up to six times without significant loss of activity.

A broad spectrum of optically active amine components is available in a first step with good to excellent enantioselectivity.

Highly enantiomerically enriched N-protected α-amino acids can be easily prepared from optically pure N-(tert-butanesulfinyl)imines by a four-step sequence involving: diastereoselective addition of a triorganozincate to the imine, removal of the sulfinyl group, benzoylation of the nitrogen atom of the obtained primary amine and oxidation of one of the substituents on the carbon atom α to the nitrogen. Using the same configuration in the sulfinyl chiral auxiliary, amino acids with the (R) or the (S) configuration can be prepared by choosing the proper combination of imine and organozincate. α,α-Disubstituted α-amino esters with high optical purity can also be prepared by the diastereoselective addition of trialkylzincates to α-imino esters.

The addition of triorganozincates to (R)-N-(tert-butanesulfinyl)benzaldimine has been performed with very good results by using a catalytic amount of Me2Zn (0.15 equiv) to generate the organozincate. Yields and/or diastereoselectivities of the formed α-branched sulfinamides improve in comparison with the values obtained in the same reactions carried out with an excess of a previously formed triorganozincate. On the other hand, the transfer of the two alkyl groups of a dialkylzinc reagent to the imine has been achieved by using 0.5 equiv of dialkylzinc and 1.5 equiv of MeMgBr to generate the trialkylzincate. In both methods, good to excellent yields and diastereomeric ratios (up to 98:2) have been obtained.