Rhodium catalyzed aqueous biphasic hydroformylation of naturally occurring allylbenzenes in the presence of water-soluble phosphorus ligands

The rhodium-catalyzed hydroformylation of eugenol was performed in aqueous biphasic systems using various water soluble phosphines: TPPTS (triphenylphosphinetrisulphonated); BDPPETS (bisdiphenylphosphinoethanetetrasulphonated), BDPPPTS (bisdiphenylphosphinopropanetetrasulphonated) and BISBIS (diphosphane 2,2'-bis(diphenylphosphinomethyl)-1,1'-biphenyl disuphonated). The addition of the cationic surfactant CTAB (cetyltrimethylammonium bromide) increased the reaction rate; however, high surfactant concentrations unfavorably affected the reaction selectivity. The regio-selectivity of the hydroformylation was strongly depended on the ligand nature. The procedure was successfully extended to other allylbenzenes, i.e., estragole and safrole, producing several fragrance compounds starting from the substrates easily available from natural bio-renewable resources. (C) 2014 Elsevier B.V. All rights reserved.