Rh-TPPTS/LDH — A new heterogeneous catalyst for the synthesis of functionalized γ-lactone

Well defined Zn2Al-NO3/CO3 and Zn2Ga-NO3/CO3 LDH were prepared using typical procedures starting from Zn(NO3)2, Al(NO3)3 and Ga(NO3)3. Rh-TPPTS complex was prepared by simple complexation of a Rh precursor [Rh(cod)Cl]2 and TPPTS (3,3′,″-phosphanetriyl benzenesulfonic acid) in water. The heterogeneization of the Rh-TPPTS complex was performed by anionic exchange between Rh-complex and Zn2Al-NO3/CO3 or Zn2Ga-NO3/CO3 LDH supports. The catalysts structures and the chemical composition were confirmed by XRD analysis, XPS and DRIFT spectroscopy. Triphenylphosphane-substituted Rh heterogeneous catalysts showed good catalytic activity and selectivity in the cycloisomerization of functionalized acetylenic acids.