| Popis: |
d -Penicillamine derived thiazolidine ligands were prepared in a two-step synthetic sequence and used in the enantioselective alkylation of a variety of aromatic aldehydes with diethylzinc at room temperature. Excellent ee , up to >99%, and nearly complete conversions were observed. Structurally analogous l -cysteine derived thiazolidine ligands were also synthesized and tested for comparative purposes, resulting in very good, albeit slightly lower selectivities, up to 89%. The combined use of these two types of thiazolidines constitutes a very interesting strategy for synthesizing both ( S ) and ( R ) enantiomers of chiral secondary alcohols, thus leading the way to a myriad of useful optically active products with opposite absolute configurations. |
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