Sulfonated Chiral Phosphines

Sinou et al. prepared several water-soluble derivatives of chiral 1,2-, 1,3- and 1,4-diphosphines. The sulfonated counterparts 1-4, respectively, of (S,S)-CHIRA-PHOS [la], (S.S)-BDPP, (S,S)-CDB, and R-PROPHOS [lb] are shown. Except for 

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The dependence of the degree of sulfonation was also studied by the Vries and co-workers [4], A remarkable effect was observed in the hydrogenation of acetophenone N-benzylimine. While the use of monosulfonated (S,S)-BDPP in an EtOAc/ H20 mixture gave the corresponding amine with 94% ee in a very fast reaction, only 2% tt was achieved when the disulfonated ligand was applied. Furthermore, ap- 

Another sulfonated derivative of BINAP was mentioned in a patent of Takasago International Corporation [8]. Cationic complexes of ruthenium and or iridium with this ligand - sulfonated on the 5- and 5 -positions of the naphthyl rings - are claimed to affect asymmetric hydrogenation of olefins, ketones, and imines. 

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Chiral-sulfonated phosphines have also been synthesized and used in the preparation of water-soluble late transition-metal complexes. These complexes, like their analogs in nonaqueous solution, can be used as homogeneous catalysts for the hydrogenation of prochiral alkenes. When the phosphine ligand has a chiral center, the alkane product can potentially be obtained in enantiomeric excess. A variety of different approaches have been used to prepare chiral phosphines that are soluble in aqueous... 

Shi, M., Chen, L.-H. Chiral phosphine Lewis base catalyzed asymmetric aza-Baylis-Hillman reaction of N-sulfonated imines with methyl vinyl ketone and phenyl acrylate. Chem. Commun. 2003,1310-1311. 

An additional access to chiral sulfonated phosphines was also described [13a,b]. The method is based on the acylation of chiral hydroxyphosphines with commercial o-sulfobenzoic anhydride and was demonstrated on a number of diphosphines based on the DIOP skeleton (Eq. 1). The chelating properties of the diphosphines were studied by preparation of cationic rhodium complexes. The presence of the o-sulfobenzoate group is thought not to influence the catalytic properties. Chiral phosphines containing a sulfonate group (e.g., 8) were also obtained from BPPM by acylation with trimellitic anhydride followed by treatment with sodium tauri-nate [13 c],... 

Chiral phosphines can be made water soluble by using similar approaches and the two most important chiral diphosphines are sulfonated 2,2 -bis-(diphenylphosphinomethyl)-l,l -binaphthyl (BINAS)-8 15 and the BISBIS 16 (Figure 9). The preparation of these types of ligands involves sulfonation with fuming sulfuric acid, similarly to the other phosphines. The position of the sulfonate groups depends on the temperature and the SO3 concentration. The oxidation of the product can be hindered by the preparation of superacidic media from orthoboric acid and anhydrous sulfuric acid. ... 

Lu J, Ye J, Duan W-L (2013) Palladium-catalyzed asymmetric addition of diarylphosphines to a, p-unsaturated sulfonic esters for the synthesis of chiral phosphine sulfonate compounds. OrgLett 15 5016-5019... 

The commercial success of rhodium-trisulfonated triphenylphosphine (TPPTS) catalysts has prompted considerable interest in TPPTS and other water-soluble ligands. The potential for new applications for the synthesis of both bulk and fine chemicals in water has led to methods for the preparation of a wide variety of sulfonated phosphines including chiral phosphines and... 

Sulfonation can be applied to prepare hydrophilic derivatives of those chiral phosphines (in which chirality is defined by the saturated hydrocarbon skeleton) which can endure the harsh conditions of this reaction. Thus, sulfonation of the following chiral phosphines can be done by 20% oleum at 0°C to give mixtures of di-, tri- and tetrasulfonated products in moderate yields ... 

Furthermore, two recent reports were published concerning bifunctional chiral phosphine catalysts 69 and 70. In both cases, N-sulfonated imines and methyl vinyl ketone in the presence of either catalyst afforded the (5)-adducts 68b,c and 71-73 in high yields with excellent enantioselectivities. 

In general, the chiral ligands are water-soluble variants of those already studied in purely organic solvents (e.g., the sulfonated chiraphos, A, cyclobutane-diop, C, BDPP, F, MeOBIPHEP-TS, Q, BIFAPS, R and the quaternary ammonium derivatives of diop, D, BDPP, E). Solubility in water could also be achieved by attaching the parent phosphine molecule to a water-soluble polymer (J, M, P). The chiral phosphinites and phosphines derived from carbohydrates (e.g., K and L) have intrinsic solubility in water. During studies of one-phase... 

Recently, Hiroi and co-workers reported a palladium-catalyzed asymmetric transformation of chiral 2-alkynyl sulfmates 142 into allenyl sulfones 145 (Scheme 4.38) [58], Treatment of 142 with Pd(OAc)2 in the presence of a phosphine ligand afforded allenylsulfones 145 with high stereospecificities (73-89%) in good yields, probably through intermediates 143 and 144. 

Hydroxy-phosphines undergo benzoylation with o-sulfobenzoic anhydride in the presence of bases (Na2C03 or BuLi) affording sulfobenzoylated phosphine products. In such a way several mono- and dihydroxy phosphines could be made soluble in water, exemplified by the chiral bisphosphines 53. It should be noted, that this general method allows the preparation of water-soluble sulfonated derivatives of acid-sensitive phosphines, such as DIOP, too, which are not accessible via direct sulfonation [56]. 

M. Shi and Y.-L. Shi reported the synthesis and application of new bifunctional axially chiral (thio) urea-phosphine organocatalysts in the asymmetric aza-Morita-Baylis-Hillman (MBH) reaction [176, 177] of N-sulfonated imines with methyl vinyl ketone (MVK), phenyl vinyl ketone (PVK), ethyl vinyl ketone (EVK) or acrolein [316]. The design of the catalyst structure is based on axially chiral BINOL-derived phosphines [317, 318] that have already been successfully utilized as bifunctional catalysts in asymmetric aza-MBH reactions. The formal replacement of the hydrogen-bonding phenol group with a (thio)urea functionality led to catalysts 166-168 (Figure 6.51). 

Alternatively, the ambident oi-hetero substituted allyl anions have been utilized as homoenolate equivalents. For example, in the presence of HMPA, allyl phenyl sulfides (251),192 allyl phenyl sulfones (252)192b c and allyl phenyl selenides (253)192d e add to a,(3-enones in a l,4(0)-mode, while allyl phenyl sulfoxides (254) and allyl phosphine oxides (255) afford 1 A j-addition exclusively, irrespective of solvent used.193 Hua has shown that additions of either chiral sulfoxide (254 R1 = R2 = R3 = R4 = H, R5 = p-tolyl) or allyl oxazaphospholidine oxide (256) occur with excellent enantioselectivity (>95% ee).194 Similarly, Ahlbrecht reports that the a-azaallyl (257) adds exclusively in a 1 A j-mode to acceptor (59) to afford 1,5-diketones (Scheme 86).195... 

A number of chiral bisphosphines related to DiPAMP(l) were prepared and evaluated in asymmetric catalysis. Many variants were closely equivalent but none were superior to the parent compound. In addition, some monophosphines containing sulfone substituents were quite effective. These had the particular advantage of being usable in water solution. Several new DIOP derivatives were tried in the hydroformylation of vinyl acetate but only modest enantiomeric excesses were achieved. A 72% enantiomeric excess was achieved on dehydrovaline under relatively forcing conditions using DiCAMP(3). This result was remarkable since these phosphine ligands generally work very poorly, if at all, on tetrasubstituted olefins. 

Inherently cationic complexes of the type [L2Rh(cod)]+ can be directly exchanged onto sulfonated divinylben-zene-styrene resins, where L2 is a chiral chelating phosphine for example, [(propraphos)Rh(cod)]+ can be cation exchanged according to Scheme 4. ... 

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