Polymerisation vs. grafting in the preparation of polymer-supported aluminium catalysts for the Diels-Alder reaction: The role of the polymeric backbone
✍ Scribed by B. Altava; M.I. Burguete; E. García-Verdugo; S.V. Luis; R.V. Salvador; M.J. Vicent
- Publisher
- Elsevier Science
- Year
- 1999
- Tongue
- French
- Weight
- 520 KB
- Volume
- 55
- Category
- Article
- ISSN
- 0040-4020
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✦ Synopsis
Several polymers containing AI Lewis acids anchored to chiral prolinol moieties have been prepared and studied as catalysts for the Diels-Alder reaction of cyclopentadiene and methacrolein. The chiral ti'agment has been introduced by grafting and by polymerisation procedures using different crosslinking agents and ratios. All supported catalysts prepared show a good activity, but the polymeric network seems to play a very important role in the determining the selectivity observed. Best results, in terms ~t enantioselectivity, are obtained when the chiral fragment is introduced through polymerisation of thc appropriate chiral monomer, but only when a high crosslinking degree (90% DVB) is used. It is sht~wn that the presence of coordinating atoms in the polymeric backbone is clearly detrimental for the selectivity observed.