Ligands glucose-derived

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. 

The bifunctional catalysts developed by Shibasaki and coworkers effective in the asymmetric cyanation of aldehydes and ketones (see Section 6.2) have been applied to good effect in the cyanation of imines. For instance, aluminium BINOL (6.65) catalyses the cyanation of aromatic and a,p-unsaturated N-fluorenylaldimines using TMSCN in good ee, while gadolinium complexes of the glucose-derived ligand (6.71) and derivatives have been used in the enantioselective cyanation of ketimines. ... 

On the other hand, with 1,2-disubstituted or certain trisubsti-tuted olefins, the chiral ligand also influences the trans/cis selectivity. For example, treatment of a glucose-derived enol ether with diazomethyl acetate in the presence of Cu[(5, 5)-/-Bu-box] (OTf) complex affords the cyclopropanation product with an excel-... 

The potential naproxen precursor 23 is accessible in 96 % yield and in 85 % ee by asymmetric hydrocyanation (cf. Section 2.5) of the aromatic olefin 22 catalyzed by a Ni° complex with a glucose-derived phosphinite ligand (Scheme 6) [27]. 

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... 

The as5mimetric hydrocyanation of alkenes has also received considerable atten-tion.h " In a representative example by RajanBabu, the glucose-derived phosphine ligand 94 allows useful enantioselectivities to be obtained in the hydrocyanation of aiyl-substituted alkenes (Scheme 72). 

Chiral Catalysts Containing Group 10 Metals (Ni, Pd, and Pt). The catalyst formed in situ from Ni(acac)2 and bomane aminoalcohols (DAB or DAIB) catalyze the enantioselective addition of diethylzinc to chalcones (254) (Fig. 21). Nickel(II)-chiral Schiff-base (the ligand derived from 1,2-diaminocyclohexane or 1,2-diaminopropane with pyrone derivative) complexes were efficient in epoxida-tion of nonfunctionalized olefins (255). Bis-ferrocenyl-triphosphane (PIGIPHOS) formed catalytically active complex with Ni(II) (256). Nickel-catalyzed asymmetric hydrocyanation of vinylarenes using glucose-derived phosphinite ligands was observed (257). 

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. 

---