700875-91-8Relevant academic research and scientific papers
Distinctive meta-directing group effect for iridium-catalyzed 1,1-diarylalkene enantioselective hydrogenation
Bess, Elizabeth N.,Sigman, Matthew S.
, p. 646 - 649 (2013/04/10)
An iridium-catalyzed asymmetric hydrogenation of 1,1-diarylkenes is described. Employing a novel, modular phosphoramidite ligand, PhosPrOx, in this transformation affords biologically relevant 1,1-diarylmethine products in good enantiomeric ratios (96.5:3
Modular syntheses of oxazolinylamine ligands and characterization of group 10 metal complexes
Caputo, Christine A.,Carneiro, Florentino D S.,Jennings, Michael C.,Jones, Nathan D.
, p. 85 - 95 (2008/02/12)
The syntheses of aminoalkyloxazoline and pyrrolidinyloxazoline ligands, each of which bear a pair of chiral centres, by both known and new routes are reported. Variable temperature NMR studies show that the known stepwise syntheses of the pyrrolidinyl compounds are not complicated by epimerization; however, coordination of one of the aminoalkyl derivatives to Pt(II) under conditions of prolonged heating to 80°C does give mixtures of diastereomeric N,N′-chelated complexes that result from inversion of the chiral centre associated with the aminoalkyl fragment. A new synthesis of pyrrolidinyloxazoline ligands that involves the Zn-catalyzed cyclization of Cbz-protected 2-cyanopyrrolidine and β-amino alcohols is also reported. This procedure offers the advantages of economy, shorter time, and fewer purification steps over the previously reported synthesis. In addition, the crystal structure of an enantiopure Pd(II) complex of an N.N′-chelated pyrrolidinyloxazoline is disclosed. This compound has a pseudo-C2 axis of symmetry, which may make it suitable for asymmetric catalytic applications.
Synthesis of all-cis-3-(2-diphenylphosphinoethyl)-1,2,4-tris(diphenylphosphinomethyl)cyclopentane (Ditricyp) from dicyclopentadiene
Kondolff, Isabelle,Feuerstein, Marie,Doucet, Henri,Santelli, Maurice
, p. 9514 - 9521 (2008/02/11)
A new tetraphosphine, all-cis-3-(2-diphenylphosphinoethyl)-1,2,4-tris(diphenylphosphinomethyl)cyclopentane (Ditricyp), has been synthesised in seven steps from commercially available dicyclopentadiene. The ozonolysis of dicyclopentadiene occurred first on the double bond of the bicycloheptene moiety. A very high chemoselective ozonolysis was observed at -60 °C leading to the diol after reductive treatment. From this diol, cis,cis,cis-3-(2-hydroxyethyl)-1,2,4-tri(hydroxymethyl)cyclopentane was obtained after a second ozonolysis. Mesylation and substitution with Ph2PLi led to the title tetradiphenylphosphine Ditricyp. The efficiency of this new tetraphosphine ligand for palladium-catalysed coupling reactions has been studied. Satisfactory results in terms of substrate/catalyst ratio have been obtained for Suzuki, Negishi and Sonogashira couplings and also for Heck vinylation reaction. After chromatographic separation, one enantiomer of this ligand associated to palladium was able to induce enantioselective allylic alkylation with modest enantiomeric excess.
Preparation of pyrrolidine-oxazoline containing ligands and their application in asymmetric transfer hydrogenation
McManus, Helen A.,Barry, Sarah M.,Andersson, Pher G.,Guiry, Patrick J.
, p. 3405 - 3416 (2007/10/03)
Nine members of a new ligand class incorporating both an oxazoline ring and a pyrrolidine unit were prepared in an efficient four-step synthesis starting from readily available chiral amino alcohols and proline. A study of these ligands in the asymmetric transfer hydrogenation of acetophenone showed that the catalysts formed from [Ir(cod)Cl]2 were the most active while those derived from [Ru(p-cymene)Cl2]2 gave the highest enantioselectivities (up to 61% ee).
