B. Altava et al., POLYMER-GRAFTED TI-TADDOL COMPLEXES - PREPARATION AND USE AS CATALYSTS IN DIELS-ALDER REACTIONS, Journal of organic chemistry, 62(10), 1997, pp. 3126-3134
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.