Catalyst Immobilization via Click Chemistry

Abstract

The authors describe a means of catalyst immobilzation utilizing the click reaction of an azide-functionalized Merrifield resin with chiral alkynyl-functionalized amino alcohols. The resulting catalyst containing a 1,2,3-triazole linker was applied to the ethylphenylzinc-mediated phenylation of various aldehydes. The authors implicate non-enantioselective pathways B and C, involving 1,2,3-triazole binding to zinc, to rationalize the moderate ee values obtained. Further, DFT calculations on model systems indicate that enthalpic differences between pathways A and B and A and C are small (ca. 0.5 and 3.0 kcal/mol, respectively).