Arene–Ruthenium Chemistry and Brønsted Acid Catalysis of a Chiral Phosphane-Hydroxyl Ligand
The phosphane-hydroxyl ligand (SC1,RC2)-Ph2PC(Ph)HC(OH)HCH2OMe (POH) displays κ1P, κ2P,O, κ3P,O,O′, and anionic deprotonated κ3P,O,O′ coordination modes toward the metallic (η6-p-MeC6H4iPr)Ru moiety. The hydroxyl group in [(η6-p-MeC6H4iPr)Ru(κ3P,O,O′-POH)][SbF6]2(3) has strong acidic properties. This complex catalyzes the Diels–Alder reaction between cyclopentadiene and trans-β-nitrostyrene or methacrolein as well as the Friedel–Crafts reaction between indole and methyl 3,3,3,-trifluoropyruvate or trans-β-nitrostyrene. Solution studies strongly indicate that complex 3 acts as a metallic Lewis acid assisted Brønsted-acid catalyst.