Polymer-supported ytterbium perfluorooctanesulfonate [Yb(OPf)3]:: A recyclable catalyst for organic reactions

Amberlyst A-21, a kind of well-known and cheap polymeric material, was treated with ytterbium perfluorooctanesulfonate [Yb(OPf(3)] giving a reagent with a ytterbium loading of 1.34 (wt%). The polymer-supported fluorous ytterbium catalyses the highly efficient nitration, esterification, Fridel-Crafts acylation, and aldol condensation. The catalyst can be recovered by simple filtration and used again without a significant loss of catalytic activity. The protocol avoids the use of fluorous solvents during the reaction or workup, which are expensive and can leach in small amounts. (C) 2008 Elsevier B.V. All rights reserved.