BINAP complex catalysts

Dupont et al. were able to obtain up to 80 % ee in the conversion of 2-phenyl-acrylic acid into (S)-2-phenylpropionic acid with the chiral [RuCl2(S)-BINAP]2NEt3 complex as catalyst in [BMIM][Bp4] melts (Scheme 5.2-9) [54]. 

Reaction experiments were performed at the substrate to catalyst ratios between 250 and 5000 (Table 1). The immobilized catalyst showed a rather constant values of TOP and enantioselectivity in spite of the increase in the S/C ratio, even though these values were slightly lower than those of the homogeneous Ru-BINAP catalyst. After the reaction, the Ru content in the reaction mixture was measured by ICP-AES and was found to be under 2 ppm, the detecting limit of the instrument, indicating the at Ru metal didn t leach significantly during the reaction. These results show that the immobilized Ru-BINAP catalyst had stable activity and enantioselectivity and that the Ru metal complex formed a stable species on the alumina support. 

Ruthenium complexes containing this ligand are able to reduce a variety of double bonds with e.e. above 95%. In order to achieve high enantioselectivity, the reactant must show a strong preference for a specific orientation when complexed with the catalyst. This ordinarily requires the presence of a functional group that can coordinate with the metal. The ruthenium-BINAP catalyst has been used successfully with unsaturated amides,23 allylic and homoallylic alcohols,24 and unsaturated carboxylic acids.25... 

Asymmetric hydrogenation of 3,4-hydroisoquinolines with Ir-chiral phosphorus ligand complexes has been studied. Although the highest enantioselectivity to date is obtained with a chiral titanocene catalyst,308,308a 308c chiral BCPM-Ir or BINAP-Ir complexes with additive phthalimide or F4-phthalimide have shown some good selectivity. Some examples are listed in Table 24. 

BINAP-Ru is effective for the diastereoselective hydrogenation of some chiral yS-keto esters (Fig. 32.13). Reaction of N-Boc-protected (S)-y-amino / -keto esters 13A catalyzed by the (R)-BINAP-Ru complex results in the syn alcohols 13B exclusively [52]. The stereocenter at the / -position is controlled by the chirality of the catalyst therefore, use of the S catalyst affords the anti isomer, as predicted. Derivatives of statine, a key component of the aspartic proteinase inhibitor pep-... 

Enantioselective hydrogenation of / -keto phosphonates in the presence of an ( R)-BINAP-Ru complex under 1-4 atm H2 and at room temperature provides the (R)-yS-hydroxy phosphonates in up to 99% ee (Fig. 32.20) [69]. The sense of enantioface selection is the same as that observed in the reaction of / -keto carboxylic esters (see Fig. 32.14). A BDPP-Ru catalyst is also usable [70]. Similarly, / -keto thiophosphonates are hydrogenated with a MeO-BIPHEP-Ru catalyst with up to 94% optical yield [69 b]. 

More recently, Noyori [2] [9] has developed a "second generation" of soluble chiral catalysts of Wilkinson-type, such as the Ru-BINAP dicarboxylate complexes which greatly extended the utility and applications of asymmetric hydrogenation. 

It is worth noting that an opposite sense of enantioface selection is observed in going from the BINAP-Rh complex to the Ru catalyst. Hydrogenation of methyl (Z)-2-(acetamido)cinnamate with the (7 )-BlNAP-Ru catalyst in CH3OH gives the R (not S) product selectively (Figure pq) p g j-g illustrates the... 

In the presence of a cationic Rh[((/ )-binap)(cod)] complex, geranyl or neryl amides isomerize slowly to give a mixture of the corresponding enamide and dienamide (Scheme 20) (2). The optical purity of the chiral enamide is high, but the chemical yield is low. Certain cyclic allylic amides give the enamide isomers in a high ee. With a DIOP-Rh catalyst, prochiral allylic alcohols are converted to optically active aldehydes with low ee (31). 

The synthesis of the C20—C26 fragment started with a 4-alkylation of methyl aceto-acetate The first stereocentre was introduced by enantioselecuve catalytic hydrogenation with Noyort s (S)-binap rhodium complex (cf p 102f.) Stereoselective Frater-Seebach alkylation with allyl bromide introduced the second stereocentre in 90% yield (cf p 27) Stereospecifid introduction of the stereocentres C24 and C2 was achieved by a chelation controlled addition of an allylstannane to an aldehyde (see p 66f) After some experimentation with Lewis acid catalysts and reaction conditions a single diastereomer of the desired configuration was ob-... 

Trimethylindolenine was hydrogenated with a catalyst consisting of [IrCl(COD)]2, (R,R)-BICP, and phthalimide in CH2C12 under 68 atm of H2 to afford the chiral cyclic amine in 95.1% ee (Scheme 9) [20]. The addition of phthalimide remarkably increased the optical yield [21]. Hydrogenation of a dihydroisoquinoline compound with a neutral (R)-BINAP/Ir complex in... 

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