POLYMER-GRAFTED TI-TADDOL COMPLEXES - PREPARATION AND USE AS CATALYSTS IN DIELS-ALDER REACTIONS

Different strategies have been evaluated for the preparation of polyme rs functionalized with chiral fragments containing the ha,alpha,alpha' ,alpha'-tetraaryl-1,3-dioxolane-4,5 -dimethanol (TADDOL) structure. Be st results are obtained when TADDOL derivatives containing OH phenolic groups (17 and 18) are prepared in solution and then selectively anch ored to chloromethylated polymers by reaction in THF containing NaH an d small amounts of 18C6 and NBu4I. Resins 19 having the desired functi onality have been prepared in this way. The procedure allows the effic ient introduction of this functional group in PS-DVB polymers with dif ferent loading and cross-linking degrees, as well as on SMOP resins. T hese functionalized resins have been used to prepare Ti-TADDOL-support ed complexes which have been tested as catalysts in the reaction of cy clopentadiene with 3-crotonoyl-1,3-oxazolidin-2-one. Although all the polymers obtained efficiently catalyze the reaction, only the one prep ared from ra-3,5-dimethylphenyl-1,3-dioxolane-4,5-dimethanol induces a symmetry.