title: Pincer Ru and Os complexes as efficient catalysts for racemization and deuteration of alcohols.
abstract: The pincer complexes [MX(CNN)(PP)] (M = Ru, Os; X = Cl, OTf; HCNN = 1-(6-arylpyridin-2-yl)methanamine; PP = diphosphine) have proven to efficiently catalyze both racemization and deuteration of alcohols in the presence of a base. Chiral alcohols have been racemized at 30-50 °C using 1 mol% of Ru or Os pincer complexes and 5 mol% of KOtBu in 2-propanol. Primary and secondary alcohols are efficiently deuterated at the α position, with respect to the OH group, using 2-propanol-d(8) as solvent with Ru or Os pincer complexes and KOtBu at 30-50 °C. For secondary alcohols incorporation of deuterium at the β position has also been observed. In 2-propanol-d(8) the pincer complexes catalyze the simultaneous deuteration and racemization of (S)-1-phenylethanol, the two processes being strictly correlated. For both reactions much the same activity has been observed with the Ru and Os complexes. The pincer complexes display a superior activity with respect to the related compounds [MCl(2)(NN)(PP)] (NN = bidentate amine or pyridine ligand). The synthesis of the new complexes [MCl(CNN)(PP)] (M = Ru, 2, 4 and Os, 6, 7; PP = dppb, dppf) and [Ru(OTf)(CNN)(dppb)] (3) is also reported.
authors.affiliation: Dipartimento di Chimica, Fisica e Ambiente, Università di Udine, Via Cotonificio 108, I-33100, Udine, Italy.
authors.forename: Gianluca
authors.initials: G
authors.lastname: Bossi
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Putignano
authors.forename: Pierluigi
authors.initials: P
authors.lastname: Rigo
authors.forename: Walter
authors.initials: W
authors.lastname: Baratta