Polymer-supported chiral diol as ligand of Ti(IV) for enantioselective Diels-Alder reaction

Chiral catalysts immobilized on achiral polymers: effect of the polymer support on the performance of the catalyst

“…Some increases in activity, relative to the homogeneous phase, have been also reported by Irurre et al using polymer-supported Ti-TADDOLates. 129,130 The high potential of TADDOL ligands (a,a,a 0 ,a 0 -tetraaryl-1,3-dioxolane-4,5-dimethanol) as chiral auxiliaries in catalysis and separation processes 131 has led different groups to study their immobilization on a variety of supports. [132][133][134][135][136][137][138][139] In the case of supported Ti-TADDOLates 62 (Fig.…”

“…[132][133][134][135][136][137][138][139] In the case of supported Ti-TADDOLates 62 (Fig. 10) prepared by grafting and studied for the Diels-Alder cycloaddition of cyclopentadiene and 3-crotonoyl-1,3-oxazolidin-2-one using a 10 : 1 catalyst dienophile ratio, 129,130 no clear rationale was given to explain the observed increase in activity, but the presence of changes in the mechanism can be envisaged, in particular taking into account the potential participation in this reaction of several complexes with different molecularities. 140 An even more dramatic effect was observed in the case of some b-amino alcohol derivatives (Fig.…”

Recoverable Catalysts and Reagents Using Recyclable Polystyrene-Based Supports

“…The use of PS-supported Ti (IV)-TADDOLate 2.28 (Scheme ) as an asymmetric catalyst for the Diels−Alder cycloaddition of cyclopentadiene with 3-crotonoyl-1,3-oxazolidin-2-one ( 2.29 ) has been reported …”

A Simple Batch Reactor for the Efficient Multiple Use of Polymer-Bound α,α,α‘,α‘-Tetraaryl-1,3-dioxolane-4,5-dimethanol Titanates in the Nucleophilic Addition of Dialkylzinc Reagents to Aldehydes

“…There have also been several examples of ligand-mediated reactions in which the chiral ligand was incorporated into a polymeric backbone. Recently, these have included new catalysts for asymmetric dihydroxylation, Diels−Alder reactions, and asymmetric epoxidation …”