128310-70-3Relevant articles and documents
trans-RuH(η1-BH4)(binap)(1,2-diamine): A catalyst for asymmetric hydrogenation of simple ketones under base-free conditions
Ohkuma, Takeshi,Koizumi, Masatoshi,Muniz, Kilian,Hilt, Gerhard,Kabuto, Chizuko,Noyori, Ryoji
, p. 6508 - 6509 (2002)
(Chemical Equqtion Presentation) Reaction of a chiral RuCl2(diphosphine)(1,2-diamine) complex and NaBH4 forms trans-RuH(η1-BH4)(diphosphine)(1,2-diamine) quantitatively. The TolBINAP/DPEN Ru complex has been characterized by single crystal X-ray analysis as well as NMR and IR spectra. The new Ru complexes allow for asymmetric hydrogenation of simple ketones in 2-propanol without an additional strong base. Various base-sensitive ketones are convertible to chiral alcohols in a high enantiomeric purity with a substrate/catalyst ratio of up to 100 000 under mild conditions. Configurationally unstable 2-isopropyl- and 2-methoxycyclohexanone can be kinetically resolved with a high enantiomer discrimination. This procedure overcomes the drawback of an earlier method using RuCl2(diphosphine)(diamine) and an alkaline base, which sometimes causes undesired reactions such as ester exchange, epoxy-ring opening, β-elimination, and polymerization of ketonic substrates. Copyright
Asymmetric Transfer Hydrogenation of Ketones with Well-Defined Manganese(I) PNN and PNNP Complexes
Demmans, Karl Z.,Olson, Maxwell E.,Morris, Robert H.
supporting information, p. 4608 - 4618 (2019/01/04)
Three new manganese complexes trans-[Mn(P-NH-NH-P)(CO)2][Br], (14) P-NH-NH-P = (S,S)-PPh2CH2CH2NH-CHPhCHPhNHCH2CH2PPh2), fac-[Mn(P′-NH-NH2)(CO)3][Br], (15) P′-NH-NH2 = (S,S)-PPh2(C6H4)NHCHPhCHPhNH2, and syn-mer-Mn(P-NH-NH2)(CO)2Br, (16) P-NH-NH2 = (S,S)-PPh2CH2CH2NHCHPhCHPhNH2 were synthesized and tested for the asymmetric transfer hydrogenation (ATH) of acetophenone in 2-PrOH. The ligands have stereogenic centers derived from the starting diamine, (S,S)-DPEN. Complex 16 was shown by NOE NMR experiments to have Mn-Br syn to the N-H of the secondary amine. Only the precatalyst 16, upon reaction with potassium tert-butoxide (KOtBu) in 2-PrOH, generated an active system at 80 °C for the ATH of acetophenone to 1-phenylethanol in an enantiomeric excess (ee) of 42% and thus was selected for further investigation into the mechanism of transfer hydrogenation. The corresponding amido complex Mn(P-N-NH2)(CO)2 (17), a borohydride complex syn-mer-Mn(P-NH-NH2)(CO)2(BH4) (18), and an ethoxide complex anti-mer-Mn(P-NH-NH2)(CO)2(OEt) (19′) were independently synthesized and tested in the ATH of acetophenone. The amido complex 17 and the borohydride complex 18 displayed similar activity to 16 activated in basic 2-PrOH, but the anti NH OEt complex 19′ was completely inactive. This result suggested that the NH effect, as described by Noyori, was required to obtain catalytic activity. The syn NH BH4 manganese complex is one of the most active manganese ATH catalysts to date and can hydrogenate a variety of aromatic ketones, including base-sensitive substrates such as p-acetylbenzoate ethyl ester.
Applications of ruthenium hydride borohydride complexes containing phosphinite and diamine ligands to asymmetric catalytic reactions
Guo, Rongwei,Chen, Xuanhua,Elpelt, Christian,Song, Datong,Morris, Robert H.
, p. 1757 - 1759 (2007/10/03)
(Chemical Equation Presented) A series of novel trans-ruthenium hydride borohydride complexes with chiral phosphinite and diamine ligands were synthesized. They can be used in the asymmetric transfer hydrogenation of aryl ketones, including base-sensitive
