Synthesis of Chiral Vanadium Phosphonates and Their Catalytic Activity

Abstract

Treatment of vanadium starting materials with chiral and achiral phosphonic acids and phosphonates provided the soluble [BuPPh3]4[(V 2O2(OH)2)6(O3PR)8] R = CH(CH2Ph)Pr and CH(Et)Pr, [(VO)6(O3PR) 8{Cl}] R = CH2Ph, CHMePh-S, and [(V 14O22)(OH)4(O3PR)8] 6- with R = CHEtPr, CH(CH2Ph)Pr, and CH(Me)Ph- S cage complexes. These are the first reported examples of vanadium phosphonate cage molecules synthesized with racemic and enantiopure phosphonate starting materials. In addition, treatment of V2O 5 with (HO)2P(O)R in ethanol, where R = Ph and CHMePh- S, afforded (VO)(O3PR)·yEtOH·xH2O. (VO)(O3PCHMePh-S)·H2O is the first layered vanadium phosphonate material synthesized using an enantiopure phosphonic acid. These materials were tested for catalytic activity in the asymmetric epoxidation of geraniol and cinnamyl alcohol.