Sulfonated 2,2 -bis diphenylphosphino

Special chelating ligands, such as BINAS (sulfonated 2,2 -bis(diphenylphosphino-methyl)-l,l -binaphthylene) [40, 41] and BISBIS (sulfonated 2,2 -bis(diphenylphos-phinomethyl)-1,1 -biphenyl) [42], were found to be very useful ligands for the two-phase hydroformylation of higher alkenes. Under standard conditions with BINAS a relatively high conversion of 36% is achieved (Table 11). In the presence of only 0.24 wt.% of tetradecyltrimethylammonium BINAS in the catalyst phase, the conversion rate rises to 77% (3 h) or 84% (6h). In addition it should be mentioned that no decrease of the excellent n/iso ratio of 99 1 is observed with BINAS, as opposed to TPPTS. 

The aqueous biphase hydrogenation of dimethyl itaconate is accomplished with an Ir-(7 )-(7 )-3-benzyl(/>-sulfonate)-2,4-bis(diphenylphosphino)pentane complex.605... 

It then became clear that only certain ortl o-substituted or heterocyclic carboxylic acids undergo this reaction. To overcome this limitation, Goossen and coworkers [33] employed aryl sulfonates instead of aryl halides as the coupling partners in combination with a catalyst generated in situ from Pdl2, tolyl-2,2 -bis(diphenylphosphino)-l,l -binaphthyl (Tol-BINAP) or P(p-Tol)3, CUjO, and phenanthroline. The weakly coordinating triflate ions, released in the cross-coupling step, are unable... 

Sulfonate groups can also be introduced during the course of the diphosphine synthesis. For example, as shown in Scheme 1, the surfactant sulfonate derivative of bis(diphenylphosphino)pentane is formed by reaction of Li P[C6H4(CH2)3C6H5]2 with (R,R)-2,4-pentanediylditosylate and subsequent sulfonation with sulfuric acid [10]. Here, the phenyl group that is not attached directly to phosphorus is less deactivated for sulfonation. 

Scheme 1 Synthesis of the surfactant sulfonate derivative of 2,4-bis(diphenylphosphino) pentane.

Enantioselective hydrogenation of imines in aqueous systems remains a challenge. iV-benzylacetophenoneimine could be hydrogenated in water-ethyl acetate biphasic mixtures with catalysts prepared from [Rh(COD)Cl]2 and various sulfonated diphosphines (Scheme 7). It was observed that when sulfonated (2S,4S)-bis-2,4(diphenylphosphino)pentane (BDPP) was used as ligand the enan-tioselectivity was a function of the degree of sulfonation (96,97). With the mono-sulfonated phosphine, BDPPMS 94% ee could be obtained whereas only 63% ee... 

Fig. 1 Reaction scheme for the synthesis of the 2 -0-allyluridine building block Reagents i, l,3-dichlorO l,l,3,3-tetraisopropyldisiloxane in pyridine ii, chlorotri-methylsilane, and triethylamine in 1,2-dichloroethane, iii, 2-mesitylenesulfonyl chloride, triethylamine, and 4-dimethyIaminopyndine in dichloromethane iv, 2,6-dichlorophenol, l,4-diazabicyclo[2 2.2]octane and triethylamine v, p-toluene sulfonic acid monohydrate in THF/dichloromethane, vi, allyl ethyl carbonate, l,4-bis(diphenylphosphino)butane and tris(dibenzylideneacetone)dipalladium(0) in tetrahydrofuran, vii, tetrabutylammonium fluoride in tetrahydrofuran viii, 2-nitro-benzaldoxime and 1,1,3,3-tetramethylguanidine in acetonitrile, ix, 4,4 -dimethoxytrityl chloride and triethylamine in pyridine x, 2-cyanoethoxy M -diisopropyl-aminochlorophosphine and //,iV-diisopropylethyiamine in 1,2-dichloroethane.

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