Conformational aspects of some asymmetric Diels-Alder reactions. A molecular mechanics + polarization study

✍ Scribed by Francisco Torrens; Manuel Ruiz-López; Carlos Cativiela; José I. García; José A. Mayoral

• Book ID: 104205159
• Publisher: Elsevier Science
• Year: 1992
• Tongue: French
• Weight: 602 KB
• Volume: 48
• Category: Article
• ISSN: 0040-4020
• DOI: 10.1016/s0040-4020(01)90129-2

✦ Synopsis

The MM2 force field, improved by the inclusion of interacting induced dipole (ID) energies, is used to calculate the conformational preferences of three chiral dienophiles: Acrylate of (S)-ethyl lactate (l), N-acryloyl+phenylalanine methyl ester (2), and N-acryloyl-Lalanine methyl ester (3). The results obtained agree with the models previously proposed to account for the asymmetric induction obtained in the reaction of these dienophiles with cyclopentadiene. Acrylates of chiral a-hydroxy acid derivatives1 and N-acryloyl-a-amino acid derivatives2 have been used as chiral dienophiles in asymmetric Diels-Alder reactions. It has been shown that both the diastereofacial selectivity and the direction of the asymmetric induction, depend on the nature of the dienophile and the Lewis acid used as a catalyst. In order to explain the results obtained, three different models have been proposed for the dienophile-catalyst complexes:

&Al. . l .