Phosphinite, oxazoline

The oxazoline-derived P,N ligands can be classified into four groups according to structure phosphino-oxazolines phosphite- and phosphinite-oxazolines catalysts containing a P-N bond and structurally related non-oxazoline catalysts. 

Reactions of the same substrate with several nucleophiles were also catalyzed by the water-soluble Pd-complex of a phosphinite-oxazoline ligand which was prepared from natural D-glucosamine (Scheme 6.23) [53]. The catalyst dissolves weU both in water and in CH3CN but not in diethyl ether. Therefore the reactions could be ran either in water/toluene biphasic systems or in homogeneous water/CHaCN solutions. In the latter case, phase separation could be induced by addition of diethyl ether upon which the catalyst moved quantitatively to the aqueous phase. The product was obtained from the organic phase by evaporation of the solvent(s) and the aqueous solution of the Pd-complex was recycled. In aqueous systems the... 

SYNTHESIS AND APPLICATION OF PHOSPHINITE OXAZOLINE IRIDIUM COMPLEXES FOR THE ASYMMETRIC HYDROGENATION OF ALKENES... 

Table 2.2 Enantioselective hydrogenation of franr-a-methylstilbene using a phosphinite oxazoline iridium complex at different catalyst to substrate ratios...

The extraction concept is also applicable to sophisticated syntheses of fine-chemicals as recently shown by Ohe, Uemura and co-workers [35], They prepared a novel amphiphilic phosphinite-oxazoline chiral ligand based on D-glucosamine. The corresponding palladium complex was an efficient catalyst for asymmetric allylic substitution reactions and could be recycled by simple acid/base extraction and reused in the second reaction without loss of enantioselectivity. 

Ohe and coworkers [47] developed the phosphinite oxazoline Hgands 78, derived from D-glucosamine. They appUed these hgands to the Mizoroki-Heck reaction of phenyl triflate... 

Yonehara, K., Mori, K., Hashizume, T. et al. (2000) Palladium-catalyzed asymmetric inter-molecular arylation of cyclic or acyclic alkenes using phosphinite-oxazoline ligands derived from D-glucosamine. J. Organomet. Chem., 603, 40-9. 

Uemura and coworkers used a carbohydrate-based phosphinite-oxazoline prepared from D-glucosamine as hgand for palladium in the alkylation of l,3-diphenyl-3-acetoxyprop-l-ene in water or in an aqueous/organic biphasic medium. High yields of alkylation products were obtained with up to 85% ee (Scheme 8.23). ... 

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