Phosphites hydroformylation catalyzed

Rhodium precipitation in solubilized rhodium-phosphite complex catalyzed liquid recycle hydroformylation may be minimized or prevented by carrying out product recovery in the presence of an organic polymer containing polar functional groups such as amides, ketones, carbamates, ureas and carbonates.[20] Patent examples include the use of polyvinylpyrrolidone and vinylpyrrolidone-vinyl acetate copolymer with diorganophosphite-modified rhodium catalysts. 

Asymmetric hydroformylation catalyzed by highly cross-linked polystyrene-sup-ported RS-BINAPHOS-Rh(I) complexes (phosphin-phosphite catalysts including dinaphtho-l,3,2-dioxaphosphepine ligands) 03YGK694. 

A phosphite-modified calixarene with unsubstituted hydroxyl groups was used as a ligand in 1-hexene hydroformylation catalyzed by rhodium complexes [224], The reaction was carried out at a synthesis gas pressure of 6.0 MPa and 160 °C. Rh(acac)(CO)2 was a catalyst precursor. In 3 h, the conversion of the initial alkene virtually reached its theoretically predicted value the yield of aldehydes was 80-85%, and the normal-to-isomeric aldehyde ratio was approximately 1 1. Some similar phosphites 83 were also studied as components of catalytic systems for 1-octene hydroformylation [225]. It was shown that the nature and steric volume of substituent R have no essential effect on the main laws of the process. For example, the conversion was 80-90% at a selectivity with respect to nonanal of about 60% in all cases. The regioselectivity with respect to nonanal was considerably increased to 90-92% by using the chelate biphosphite 84 [220]. 

HP-NMR) and in situ high-pressure infrared (HPIR) characterizations of intermediates on asymmetric hydroformylation catalyzed by rhodium phosphine-phosphite, diphosphites and diphosphines allowed to elucidate mechanistic aspects of the reaction, especially the steps determining the reaction rate and the formation of the intermediates of the reaction [9,12]. 

Rhodium catalyzed reaction of A -butenyl-l,3-propanediamines 397 with a mixture of H2 and CO gave usually a mixture of hydroformylated 398 and 399 and carbonylated products 400 and 401 in the presence of a phosphite [PPha, PBu3, PCCgHiOa, P(o-tol)3] (97TL4315, 97T17449). When the hindered biphosphite, BIPEPHOS, and a 9 1 or 1 1 mixture of H2 and... 

Olivier-Bourbigou s group, for example, has recently shown that phosphite ligands can be used in Rh-catalyzed hydroformylation in ionic liquids as well as the well loiown phosphine systems [81]. Since phosphite ligands are usually unstable in aqueous media, this adds (apart from the much better solubility of higher olefins in... 

Phosphites have been used as ligands in Rh-catalyzed hydroformylation from the early days since their introduction in 1969.205 206 Identification of complexes occurred more recently. Ziolkowski and Trzeciak have studied extensively the use of phosphite ligands in the Rh-catalyzed hydroformylation of alkenes.207-210 The ligand tris(2-/er/-butyl-4-methylphenyl) phosphite (65) leads to extremely fast catalysis and in situ spectroscopy showed that under the reaction conditions only a mono-ligated complex [Rh(H)(CO)3(65)], (66), is formed due the bulkiness of the ligand.211-213... 

Chiral thioureas have been synthesized and used as ligands for the asymmetric hydroformylation of styrene catalyzed by rhodium(I) complexes. The best results were obtained with /V-phenyl-TV -OS )-(l-phenylethyl)thiourea associated with a cationic rhodium(I) precursor, and asymmetric induction of 40% was then achieved.387,388 Chiral polyether-phosphite ligands derived from (5)-binaphthol were prepared and combined with [Rh(cod)2]BF4. These systems showed high activity, chemo- and regio-selectivity for the catalytic enantioselective hydroformylation of styrene in thermoregulated phase-transfer conditions. Ee values of up to 25% were obtained and recycling was possible without loss of enantioselectivity.389... 

Chiral thioether-phosphite ligands (125) derived from 1,2-O-isopropylidenexylofuranose have been synthesized. Reaction of these chiral ligands with [Rh(cod)2]BF4 yielded [Rh(cod)(125)]BF4. These ligands were tested in the Rh-catalyzed hydroformylation of styrene. The hydroformylation results (ee values were insignificant) are discussed according to the solution structure of the species formed under hydroformylation conditions. HP NMR studies show that only the phosphite is coordinated during the catalytic reaction.390... 

Inspired by the excellent results using the BINAPHOS ligands, new phosphine-phosphite ligands with different backbones have been developed in recent years. Unfortunately, their Rh-catalyzed hydroformylation provided low-to-moderate enantioselectivity (ee s from 20 to 62%) [35,36,65]. 

The phosphine-phosphite BINAPHOS ligand was first used in the Rh-catalyzed asymmetric hydroformylation of heterocyclic olefins such as 2,5-dihydrofuran, 3-pyrroline derivatives, and 4,7-dihydro-1,3-dioxepin derivatives. It provided the optically active aldehydes as single products with enantioselectivity between 64-76% ee. In the hydroformylation of 2,5-di-... 

In order to assess structural influences on the catalytic performance of mono-cyclic PEG-modifled phosphites, the monocyclic phosphites 14a,c, 17a-e, and 19b,c were used in the rhodium-catalyzed hydroformylation of 1-octene (Scheme 6). The catalysts were prepared in situ by adding a solution of [Rh(acac)(CO)2] as a catalyst precursor in toluene to the phosphite ligands... 

Schemes Rh-catalyzed hydroformylation of -octene using phosphites 14,17, and 19...

Generally, one would expect that increasing steric hindrance in the catalytically active rhodium complex would result in lower reaction rates. In this respect, the results of Van Leeuwen and Roobeek seemed at first to be contradictory. They used the very bulky tris(ortho tert-butylphenyl)phosphite la (Chart 6.1) as a ligand and found high reaction rates in the rhodium catalyzed hydroformylation of other-... 

Chart 6.2 Intermediates in the tris (2-tert-butyl-4-methyl phenyl) phosphite modified Rhodium catalyzed hydroformylation. 

Slagt. V.F., van Leeuwen, P.W.N.M. and Reek, f.N.H. (2003) Midticomponent porphyrin assemblies as functional bidentate phosphite ligands for regioselective rhodium-catalyzed hydroformylation. Angew. Chem., Int. Ed., 42, 5619-5623. 

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