Biphasic hydroformylation of substituted allylbenzenes with water-soluble rhodium or ruthenium complexes Original Research Article

The water-soluble complexes [Rh(CO)(Pz)(L)]2 and [HRu(CO)(CH3CN)(L)3][BF4] [L = TPPMS (m-sulfonatophenyl-diphenylphosphine) and TPPTS (tris-m-sulfonato-phenylphosphine)] were used for the first time as catalyst precursors for the hydroformylation of eugenol, estragole, safrole and trans-anethole under moderate conditions in biphasic media. Under mild reaction conditions the substrates showed the following reactivity order: eugenol > estragole ≈ safrole ≫ trans-anethole. The use of cetyl-trimethylammonium chloride (CTAC) as phase transfer agent inhibits the isomerization reaction, reaching high selectivity for the hydroformylation products (80–94%). The catalytic phase can be recycled up to four times with a decrease in the activity over time but maintaining its high selectivity.