Rhodium catalysts asymmetric hydroformylation

Styrene, a-ethyl-asymmetric hydroformylation catalysts, platinum complexes, 6, 266 asymmetric hydrogenation catalysts, rhodium complexes, 6, 250 Styrene, a-methyl-asymmetric carbonylation catalysis by palladium complexes, 6, 293 carbonylation... 

Platinum complexes with chiral phosphorus ligands have been extensively used in asymmetric hydroformylation. In most cases, styrene has been used as the substrate to evaluate the efficiency of the catalyst systems. In addition, styrere was of interest as a model intermediate in the synthesis of arylpropionic acids, a family of anti-inflammatory drugs.308,309 Until 1993 the best enantio-selectivities in asymmetric hydroformylation were provided by platinum complexes, although the activities and regioselectivities were, in many cases, far from the obtained for rhodium catalysts. A report on asymmetric carbonylation was published in 1993.310 Two reviews dedicated to asymmetric hydroformylation, which appeared in 1995, include the most important studies and results on platinum-catalogued asymmetric hydroformylation.80,81 A report appeared in 1999 about hydrocarbonylation of carbon-carbon double bonds catalyzed by Ptn complexes, including a proposal for a mechanism for this process.311... 

Chiral diphosphites based on (2R,3R)-butane-2,3-diol, (2R,4R)-pentane-2,4-diol, (25, 5S)-hexane-2,5-diol, (lS -diphenylpropane-hS-diol, and tV-benzyltartarimide as chiral bridges have been used in the Rh-catalyzed asymmetric hydroformylation of styrene. Enantioselectivities up to 76%, at 50% conversion, have been obtained with stable hydridorhodium diphosphite catalysts. The solution structures of [RhH(L)(CO)2] complexes have been studied NMR and IR spectroscopic data revealed fluxional behavior. Depending on the structure of the bridge, the diphosphite adopts equatorial-equatorial or equatorial-axial coordination to the rhodium. The structure and the stability of the catalysts play a role in the asymmetric induction.218... 

A chiral diphosphite based on binaphthol, coordinated with rhodium (I) forming a nine-member ed ring, led to an efficient hydroformylation of vinylarenes, although moderate ees were obtained (up to 46%) at mild pressure and temperature reaction conditions.364 Chiral diphosphites and phosphinite-phosphites derived from spiro[4.4]nonane-l,6-diol were synthesized. Using these catalysts in the asymmetric hydroformylation of styrene, high regioselectivity (97%) and... 

The monosulfonated PPh derivative, Ph2P(m-C6H4S03K) (DPM) and its rhodium complex, HRh(CO)(DPM)3 have been synthesized and characterized by IR and NMR spectroscopic techniques. The data showed that the structure was similar to [HRh(CO)(PPh3)3]. The catalytic activity and selectivity of [HRh(CO)(DPM)3] in styrene hydroformylation were studied in biphasic catalytic systems.420 421 Rh1 complexes [Rh(acac)(CO)(PR3)] with tpa (131), cyep (132), (126), ompp (133), pmpp (134), tmpp (135), PPh2(pyl), PPh(pyl)2, and P(pyl)3 were characterized with NMR and IR spectra. Complexes with (131), (132), and (126) were catalysts for hydrogenation of C—C and C—O bonds, isomerization of alkenes, and hydroformylation of alkenes.422 Asymmetric hydroformylation of styrene was performed using as catalyst precursor [Rh(//-0 Me)(COD)]2 associated with sodium salts of m-sulfonated diarylphosphines.423... 

TABLE 3.1. Asymmetric hydroformylation of styrene using polystyrene supported rhodium catalysts based... 

After the discovery of the high ee provided by rhodium/diphosphite and rhodium/phosphine-phosphite complexes, with total conversion in aldehydes and high regioselectivities, rhodium systems became the catalysts of choice for asymmetric hydroformylation. Important breakthroughs in this area have been the use of rhodium systems with chiral diphosphites derived from... 

Asymmetric rhodium catalysts are discussed in section 8.6. The most interesting ligand discovered for asymmetric hydroformylation is undoubtedly BINAPHOS, introduced by Takaya [18], but certain diphosphites also give high enantioselectivities [19,20],... 

The other three studies in the literature also deal with the asymmetric hydroformylation of styrene and all three applied water soluble rhodium -phosphine catalysts (Scheme 4.9). BINAS (44), sulfonated BIPHLOPHOS (43), tetrasulfonated (R,R)-cyclobutane-DIOP (37, m=0) and tetrasulfonated (S,S)-BDPP (36, m=0) were applied as ligands of the rhodium catalyst prepared in situ from [Rh(acac)(CO)2] or [ Rh( Li-OMe)(COD) 2] and the phosphines. The results are summarized in Table 4.4. 

Figure 6 Union Carbide chiral bis-phosphite-rhodium complexes used as catalysts for the asymmetric hydroformylation.

Figure 7 A rhodium complex of chiral phosphine-phosphite ligand (H,S)-BINAPHOS used as a catalyst for asymmetric hydroformylation.

Asymmetric Hydroformylation. Hydroformylation of Olefins in the Presence of Chiral Rhodium and Cobalt Catalysts... 

Optical yields up to 17% and 25%, respectively, have been reached in the styrene hydroformylation in the presence of cobalt or rhodium catalysts using N-alkylsalicylaldimine or phosphines as asymmetric ligands. Furthermore the hydroformylation of aliphatic and internal olefins have been achieved using rhodium catalysts in the presence of optically active phosphines. With the same catalysts, cis-butene surprisingly undergoes asymmetric hydroformulation with optical yields up to 27%. On the basis of the results obtained for cis-butene and the asymmetric induction phenomena in dichlor(olefin)(amine)platinum( 11) com-... 

To obtain information about the steps in which the asymmetric induction actually takes place, 1-butene, cis-butene, and trans-butene were hydroformylated using asymmetric rhodium catalyst. According to the Wilkinson mechanism, all three olefins yield a common intermediate, the sec-butyl-rhodium complex, which, if the asymmetric ligand contains one asymmetric center, must exist in the two diastereomeric forms, IX(S) and IX(R),... 

The majority of studies of asymmetric hydroformylation with rhodium and platinum complexes have made use of DIOP (49) as a ligand. With either the complex [RhCl(CO)(DIOP)] or [RhCl(C2H4)2]2 plus DIOP, styrene was hydroformylated to 2-phenylpropanal with optical yields of only 16%.366 When a-monodeuterostyrene was used as substrate, with DIOP and complex (34) as catalyst, essentially the same optical yield was obtained.367 The same catalyst with non-deuterated styrene under different conditions gave an optical yield of 25%.368... 

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