| Popis: |
Chiral acrylates 4a, 4b and 4c, derived from primary alcohols with a single stereogenic centre, were studied for possible diastereoface differentiation in their Lewis acid catalyzed Diels-Alder reaction with cyclopentadiene. No relevant diastereomeric excess was observed for the tert-butyl derived 4a. On the other hand, moderate but significant diastereomeric excesses (72-76 %) resulted when the trityl derived acrylates 4b and 4c were used. The ability of enforcing a 1,3-parallel orientation between the aryl shielding group and the acrylate moiety by incorporation of a tert-butyl or trityl anchoring substituent in the connecting chain is qualitatively assessed by 1H NMR. |
