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A COMPARISON OF CATALYTIC ACTIVITY FOR IMINE HYDROGENATION USING RU DITERTIARY PHOSPHINE COMPLEXES, INCLUDING CHIRAL SYSTEMS

TitleA COMPARISON OF CATALYTIC ACTIVITY FOR IMINE HYDROGENATION USING RU DITERTIARY PHOSPHINE COMPLEXES, INCLUDING CHIRAL SYSTEMS
Publication TypeJournal Article
Year of Publication1994
AuthorsFogg, DE, James, BR, Kilner, M
JournalInorganica Chimica Acta
Volume222
Pagination85-90
Date PublishedJul
Type of ArticleArticle
ISBN Number0020-1693
Keywords1’-BINAPHTHYL, 2, 2’-BIS(DIPHENYLPHOSPHINO)-1, ACIDS, ASYMMETRIC HYDROGENATION, BINAP, CATALYSIS, DIPHOSPHINE, ENANTIOSELECTIVE, HYDROGENATION, IMINE HYDROGENATION, LIGANDS, NITRILE COMPLEXES, PHOSPHINE COMPLEXES, ruthenium complexes, X-ray structure
Abstract

A family of ruthenium ditertiary phosphine complexes was investigated for catalytic activity toward imine hydrogenation. The diphosphines (PP) used include chiral (chiraphos, diop, binap) and achiral (dppe, dppb) systems (chiraphos = Ph2PCH(Me)CH(Me)PPh2; diop = Ph2PCH2CHOCMe2OCHCH2PPh2; binap = 2,2’-bis(diphenylphosphino)-1,1’-binaphthyl; Ph2P(CH2)(n)PPh2 (n = 2, dppe; n = 4, dppb)). Activity was observed in MeOH at low catalyst concentrations (0.77 mM Ru), under moderate conditions (room temperature (r.t.), 1000 psi H2). The air-stable Ru2Cl5(PP)2 complexes were more active than the commonly used dimeric Ru2(II,II) systems to which they give rise in situ. Asymmetric induction in the prochiral ketimine PhCH2N = C(Me)Ph was consistent, though modest, within the diop and binap series of neutral complexes, implying a common catalytic intermediate within each series. A maximum e.e. of 27% was found using Ru2Cl5(chiraphos)2 as catalyst; this represents a non-optimized figure for asymmetric induction, as no other prochiral ketimines were screened.

URL<Go to ISI>://A1994PD17400011