D-glucose-derived ligand

We reported a catalytic enantioselective cyanosUylation of ketones that produces chiral tetrasubstituted carbons from a wide range of substrate ketones [Eq. (13.31)]. The catalyst is a titanium complex of a D-glucose-derived ligand 47. It was proposed that the reaction proceeds through a dual activation of substrate ketone by the titanium and TMSCN by the phosphine oxide (51), thus producing (l )-ketone cyanohydrins ... 

We began our synthesis by finding the optimum reaction conditions for the catalytic asymmetric cyanosilylation of ketone 28 (Table 1). Based on previous studies,30 the titanium complex of a D-glucose derived ligand (catalyst 32 or 33) generally gives (/ )-ketone cyanohydrins, which is required for a synthesis of natural fostriecin. 

An important development is the use of D-glucose-derived alkoxy ligands on titanium in cyciopentadi-enyldi(alkoxy)titanium enolates, which undergo efficient enantioselective aldol reactions with aldehydes. The chiral titanium reagent (30), prepared from reaction of cyclopentadienyltitanium trichloride with two equivalents of (l,2 5,6)-di-0-isopropylidene-a-D-glucofuranose, can be used to transmetal late the lithium enolate of t-butyl acetate in ether solution (equation 10). The titanium enolate generated is then... 

Scheme 5.15 Hydrocyanations of various 1,3-dienes with in situ generated nickel catalysts from D-glucose-derived diaiyldiphosphinite ligands.

Scheme 7.7 Alkylations of aromatic aldehydes with AlR and (AlR 3)2-DABCO in the presence of an in situ generated nickel catalyst from a D-glucose-derived phosphoramidite ligand.

Dieguez M, Pamies O, Ruiz A, Castillon S, Claver C. Chiral diphosphites derived from D-glucose new ligands for the asymmetric catalytic hydroformylation of vinyl arenes. Chem. Eur. J. 2001 7 3086-3094. 

A modified 14 with perfluoralkylphenyl groups increased the selectivity up to 96%.280 Both high enantioselectivity (91%) and high regioselectivity (98.8%) were achieved under mild conditions with a new chiral diphosphite ligand derived from D-(+)-glucose.281... 

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