Polymer-Supported Fesulphos Ligand

Significance

Synthesis of polymer-supported Fesulphos ligands and their application to asymmetric catalyses were described. Thus, the optically active Fesulphos ligand having alcohol linker 2 was prepared from ferrocene carboaldehyde 1 in six steps. Fesulphos ligand 2 was treated with Merrifield resin in the presence of NaH and a catalytic amount of NaI to provide the polymer-supported Fesulphos ligand PS-2 (eq. 1). The 1,3-dipolar cycloaddition of imines 3a-d with N-phenylmaleimide 4 in the presence of Cu(MeCN)₄ClO₄ and PS-2 gave the corresponding cycloadducts 6a-d in 92-98% yield with endo/exo selectivities of >98:<2 and with 99% to >99% ee (eq. 2). Similarly, the reaction of 3a with methyl fumarate 7 afforded the cycloadduct 8 in 92% yield with an endo/exo ratio of 80:20 and with 98% ee (eq. 3).