Synthesis of new chiral diphosphine ligand (BisbenzodioxanPhos) and its application in asymmetric catalytic hydrogenation

Substituent electronic effects in chiral ligands for asymmetric catalysis

“…It has been determined by several research groups that narrow bite angles (and therefore dihedral angles) are desirable for achieving high enantioselectivity in metal-catalysed hydrogenations [50][51][52]. As regards the electronic nature of the ligand, the majority of the most successful diphosphines for asymmetric hydrogenation have possessed biaryl backbones that are more electron-rich than the parent BINAP ligand [49][50][51]53]. Fewer examples of effective electron-deficient ligands have been reported [54,55].…”

Fast and efficient tritium labelling of the nonsteroidal anti‐inflammatory drugs naproxen, tolmetin, and zomepirac

“…However, a number of issues arise with this synthetic strategy. First, although impressive enantioselectivities have been obtained in the asymmetric reduction of this compound using chiral ruthenium catalysts, 3,4 the reaction is highly dependant on the hydrogen pressure. In general, high pressures (>100 atm) are needed in order to achieve high ee's, 4 which is incompatible with the use of tritium manifold equipment.…”

Reduction of Functionalized Alkenes

“…More recently several chiral Ru -(bisphosphine) catalysts have been used in this reaction as shown in Table 1 The bis -steroidal atropisomeric phosphine (13) has been developed from equilenine and gives up to 87% ee in the hydrogenation of ( Z ) -α -acetamidocinnamic acid [44] . A new atropisomeric ligand containing a bis -benzodioxane core Synphos was reported independently by Genet and Vidal [45] and by Chan [46] . A Ru -( S ) -Synphos complex catalyzes asymmetric hydrogenation of ( Z ) -(acylamino)cinnamate giving ( S ) -protected phenylalanine in 86% ee [45c] .…”

“…Ru( R ) -P -Phos 1 88 3( R ) [46] perfl uoroalkylated BINAP which is a useful catalyst in the asymmetric hydrogenation of methyl -2 -acetamidoacrylate in supercritical carbon dioxide with full conversion and high enantioselectivity (74% ee) [48] . The Ru -complexes of the atropisomeric family exhibit slight differences in enantioselectivity toward the same substrate.…”