Kevin M. Gillespie

Catalyst structure and the enantioselective cyclopropanation of alkenes by copper complexes of biaryldiimines: the importance of ligand acceleration

Abstract The use of chiral non-racemic biaryl copper(I) complexes in the enantioselective cyclopropanation of a number of olefins with either ethyl or tert -butyl diazoacetate is described. Lack of ligand acceleration and the presence of equilibrium amounts of catalytically active uncomplexed Cu(I) ions account for lowered enantioselectivity when using certain ligands.

Complexes of zirconium with aryl substituted triamidoamines: molecular structures of amide and alkyl derivatives

Abstract Reactions of the arylated TREN derivatives N(CH 2 CH 2 NHAr) 3 [Ar=2,4,6-C 6 Me 3 H 2 (H 3 TMT), 3,5-C 6 Bu t 2 H 3 (H 3 TDT)] individually with Zr(NMe 2 ) 4 and Zr(CH 2 Ph) 4 give the azazirconatranes [Zr(TMT)(NMe 2 )], [Zr(TDT)(NMe 2 )] and [Zr(TDT)(CH 2 Ph)] and unexpectedly [Zr(HTMT)(CH 2 Ph) 2 ]. The molecular structures of [Zr(TMT)(NMe 2 )] and [Zr(TDT)(CH 2 Ph)] show that the triamidoamine ligand is arranged with the usual three-fold symmetry about the metal and that the aryl substituents form a bowl cavity with the apical ligand at the base. The reactions of the alkyl with dihydrogen lead to decomposition, and a hydride species such as that proposed in earlier studies could not be detected.

Stereoselective catalytic tishchenko reduction of β-hydroxyketones using scandium triflate

Abstract A number of aliphatic and aromatic β-hydroxyketones were reduced to 1,3-diol monoesters by aldehydes in the presence of a catalytic amount of scandium triflate. Chiral substrates were reduced with high 1,3-anti diastereoselectivity.

Mechanism of alkene aziridination in the [(biaryldiimine)CuI] catalyst system; precise substrate orientation via two-centre binding

The highly enantioselective (⩽98%) aziridination of cinnamate esters is achieved using the title catalyst system via a concerted non-polar mechanism involving ancillary binding of carbonyl group to copper.

Bidentate carbenoid ester coordination in ruthenium(II) Schiff-base complexes leading to excellent levels of diastereo- and enantioselectivity in catalytic alkene cyclopropanation.

Exceptionally high stereoselectivity (ee < or = 98%, dr < or = 99:1) in the cyclopropanation of alkenes with ethyl diazoacetate using a non-planar ruthenium(II) Schiff-base precatalyst is a result of eta 2C,O binding of the carbenoid ester intermediate, according to DFT calculations.

Chiral-at-metal organolanthanides: enantioselective aminoalkene hydroamination/cyclisation with non-cyclopentadienyls

Chiral non-racemic complexes [ML{N(SiMe2H)2}(thf)] (M = Y, La, H2L = salicylaldimine ligands derived from 2,2′-diamino-6,6′-dimethylbiphenyl) are found not to be effective catalysts for the intramolecular hydroamination of aminoalkenes, but new amino/phenoxide ligand designs without reducible functional groups led to long-lived and enantioselective catalysts.