2R:3R-Tartaric acid

If more than one chiral center is present, the configuration at each is specified by the symbol R or S together with the number of the chiral atom. Thus the configuration of (+)-tartaric acid is known to be that designated in the name (2R,3R)-(+)-tartaric acid ... 

Figure 3 Newman projections of the staggered conformers of (A) (ft)-malic acid (X = H) and (2R,3R)-tartaric acid...

Kozma, D., Bocskei, Zs., Kassai, Cs., Simon, K., and Fogassy, E. Optical resolution of racemic alcohols by diastereoisomeric complex formation with 0,0 -dibenzoyl-(2R,3R)-tartaric acid, the crystal structure of the (-)-lR,2 S, 5R-menthol.O,0,-dibenzoyl-(2R,3R)-tartaric acid complex. J. Chem. Soc. Chem. Commun. 1996, 753-754. 

Nemak, K., Acs M., Jaszay M.Zs., Kozma, D., and Fogassy, E. Study of die diastereoisomers formed between pipecolic acid N-alkylanilides and 2R,3R-tartaric acid or 0,0 -dibenzoyl-2R,3R-tartaric acid. Do the tartaric acids form molecular complexes instead of salts during optical resolutions , Tetrahedron 1996, 52, 1637-1642. 

Figure 35, Top Enantiomorphous crystals of sodium ammonium tartrate. Hemihedral facets are marked by an h. Bottom (+)-(2R,3R)-tartaric acid (left) and (-)-(2S,35)-tartaric acid (right).

Asymmetric hydrocyanation of aldehydes.3 This reaction can be effected by reaction of aliphatic or aromatic aldehydes with cyanotrimethylsilane and an optically active reagent (1) derived from (2R,3R)-tartaric acid, and dichlorodiisopro-poxytitanium(IV). The actual chiral reagent may be 2, shown by H NMR to be... 

A study of the photochemical reactivity of salts of the amino ketone (44) with enantiomerically pure carboxylates has been reported. The irradiations involved the crystalline materials using A, > 290 nm and the reactions are fairly selective which is proposed to be the result of hindered motion within the crystalline environment. Some of the many results, using (S)-(—)-malic acid, R-(+)-malic acid and (2R,3R)-(+)-tartaric acid, are shown in Scheme 1. The principal reaction in all of the examples is a Norrish Type II hydrogen abstraction and the formation of a 1,4-biradical. This leads mainly to the cis-cyclobutanol (45) by bond formation or the keto alkene (46) by fission within the biradical. A very minor path for the malate example is cyclization to the trn 5-cyclobutanol (47). A detailed examination of the photochemical behaviour of a series of large ring diketones (48) has been carried out. Irradiation in both the solid phase and solution were compared. Norrish Type II reactivity dominates and affords two cyclobutanols (49), (50) and a ring-opened product (51) via the conventional 1,4-biradical. Only the diketone (48a) is unreactive... 

The nomenclature of optically active organic molecules has been revised since their absolute configuration has been determinable via X-ray diffraction (Chapter 6). The equivalent terms are (d)-tartaric acid = (-l-)-tartaric acid = (2R,3R)-tartaric acid (/)-tartaric acid = (—)-tartaric acid = (2S,3S)-tartaric acid mesotartaric acid = (2R,3S) tartaric acid = (2S,3R)-tartaric acid. 

Asymmetric halogenation of chiral acetals has been realized by C. Giordano (refs. 2-7). Using alkyl esters of optically active tartaric acids as chiral auxiliaries, a high diastereoselectivity is obtained even at room temperature. The results are best explained by a fast electrophilic addition of bromine on the electron rich enol ether, originating from an acid-catalyzed equilibrium with the chiral acetal. If (2R, 3R)-tartaric acid is involved, a S-configuration prevails at the new stereogenic center. Finally, cautious hydrolysis provides a set of 2-bromo alkyl aryl ketones, which can be obtained in enantiomerically pure form after crystallization (Fig. 2) ... 

Fuganti and co-workers used 2R 3R-tartaric acid for the synthesis of 3-benzamido-2,3,6-trideoxy-L-xy/o-hexose (393). The acid was converted according to a known procedure into 2,3-0-isopropylidene-4-0-p-toluenesulfonyl-L-threitol (388). Reduction of 388 with lithium aluminum hydride gave 4-deoxy-... 

The effectiveness of enantioselective hydrogenations on chiral modified RNi catalysts depends on many factors. It is influenced by variables of modification procedure, pH of solution modifier, structure of modifier, concentration of modifier, temperature of solution, period of action of modified solution, and presence of additional components. In the case of modifier (2R, 3R)-tartaric acid, it proved very important to add NaBr into the modifying solution. The amount of TA adsorbed on the catalyst determined the effectiveness of the resulting MRNi catalyst... 

Instead of the conventionally used modification by pre-immersion of the catalyst in a solution of modifier, Osawa et al. used an in situ modification during the enantioselective hydrogenation of MAA. Fine nickel powder modified with (2R,3R)-tartaric acid was used and sodium salt was added to the reaction media. By this method the optical yield was increased up to an ee of 79%. Improvement of this method consists in modification in situ of finely reduced Ni-powder by addition of (2R,3R)-tartaric acid and NaBr to the reaction media. In this case, an ee of 89% was obtained in the hydrogenation of MAA. The addition of small amounts of NaBr to the reaction media increased both the ee and the reaction rate, while, in contrast, the rate decreased with the addition of NaBr to the modification solution in... 

Table 4.4. Effects of inorganic salts, added to the (2R,3R)-tartaric acid modifying solution, on enantioselectivity in the hydrogenation of MAA on MRNi (mainly according to Harada ).

Table 4.7. Rate of formation of (R)-(-)-MHB (mmol h g ) and ee values in the enantioselective hydrogenation of methyl acetoacetate on deposited nickel-kieselguhr catalysts, promoted with 1% noble metals and modified with (2R,3R)-tartaric acid (according to summarized data of Orito et al. ).

The Ru-Cu catalysts modified with TA also proved to be not very effective. Skeletal Cu-Ru catalysts (1 1) were prepared by leaching a Cu-Ru-A1 alloy (15 15 70) at 60°C with a 20% aqueous NaOH solution. Modification of the Cu-Ru (1 1) catalyst was carried out in a 4% aqueous solution of (2R,3R)-tartaric acid at pH 4.4. Hydrogenation of EAA was carried out without solvent at 30°C and 140 bar for 5h. For comparison the hydrogenation of EAA using skeletal Ru and Cu catalysts were also examined under the same conditions. Results are summarized in Table 4.14. 

The effect of crystallite size on the optical yield was first observed by Vedenyapin et al. in the hydrogenation of ethyl acetoacetate into ethyl 3-hydrojg butyrate during progressive loading of Ru in Ru-silica catalysts that had been modified with (2R,3R)-tartaric acid. The reaction proved to be structure sensitive. The most effective catalyst proved to be the one with a 4.5 nm crystallite size, while catalysts with crystallite sizes 1.6 and 8.0 nm revealed lower asymmetric abilities. The sizes of the Ru crystallites were increased by increasing reduction times of the catalysts during their preparations. 

Figure 5.3. Effect of loading of Ru on enantioselectivity in the hydrogenation of ethyl acetoacetate into ethyl 3-hydroxybutyrate over Ru-silica catalysts modified with (2R,3R)-tartaric acid (reduction time 0.5 (upper curve) or 5 h (lower curve) crystallite sizes after 0.5h reduction time were 1.6 nm (at 1.5% Ru), 4.5 nm (at 4.2% Ru) or 8 nm (at 11.5% Ru) (according to Vedenyapin et al. ).

Nitta et al. also confirmed these effects using Ni-silica catalysts modified with (2R,3R)-tartaric acid in the hydrogenation of methyl acetoacetate (Figure 5.9.) They showed the effects on optical selectivity of the concentration of methyl (R)-(-)-3-hydroxybutyrate, which had been previously added to the reaction mixture. 

Figure 5.9. Effect of the amoimts of previously added methyl ( )-(-)-3-hydroxybutyrate to methyl acetoacetate before hydrogenation on Ni-silioa catalyst modified with (2R,3i )-tartaric acid ( ) (according to Nitta et al. and the hydrogenation of ethyl acetoacetate on Raney nickel catalyst modified with (2R,3R)-tartaric acid (o) (according to Chernysheva et al...

Electrodes made fi om Pt covered with Ni powder or Ni-black and modified with (2R,3R)-(+)-tartaric acid were more effective In die reduction of ethyl acetoacetate ee values of 8-12% were obtained. 

Table 7.1. presents the main characteristics of the process involving the reduction of beta-keio butyrate, i) acted upon by Baker s yeast, ii) using a Raney Ni catalyst modified by (2R,3R)-tartaric acid + NaBr, and iii) in the presence of a chiral Ru complex containing chiral diphosphine BINAP. 

Raney Nickel catalyst modified with (2R,3R)-tartaric acid... 

Bagi P, Kdllay M, Hessz D, Kubinyic M, Holczbauer T, Czugler M, Fogassy E, Keglevich G (2014) Resolution of l-n-propoxy-3-methyl-3-phospholene 1-oxide by diastereomeric complex formation using TADDOL derivatives and calcium salts of O, 0 -dibenzoyl-(2R,3R)-or O, 0 -di-P-toluoyl-(2R,3R)-tartaric acid. Tetrahedron Asymmetry 25 318-326... 

The Zambon process also starts from P-naphthol, and affords S-naproxen directly avoiding resolution and recycling. It is one of the few examples of a non-enzymatic, non-fermentation industrial asymmetric synthesis. Clearly, the early stages of the process produce similar waste streams to the Syntex process, with additionally waste from the Friedel-Crafts step. In principle, however, the aluminium salts can be recycled by work-up involving conversion back to aluminium chloride. The key step in this route is the highly diastereoselective (94 6) bromination of the ketal diester, derived from chirality pool 2R, 3R tartaric acid, which is used as an auxiliary. The subsequent acid catalysed 1,2-aryl shift occurs with complete inversion of configuration at the migration terminus [17]. The tartaric acid auxiliary can be efficiently recycled, but clearly there is a... 

R, 3S)-tartaric acid (2R. 3R)-tartaric acid (2S, 3S)-tartaric acid a meso compound a pair of enantiomers... 

Tartaric acid (pKi = 2.98 pK2 = 4.34) has a rough , hard sour taste. It is used for the acidification of wine, in fruit juice drinks, sour candies, ice cream, and because of its formation of metal complexes, as a synergist for antioxidants. The production of (2R,3R)-tartaric acid is achieved from wine yeast, pomace, and cask tartar, which contain a mixture of potassium hy-drogentartrate and calcium tartrate. This mixture is first converted entirely to calcium tartrate, from which tartaric acid is hberated by using sulfuric acid. Racemic tartaric acid is obtained by cis-epoxidation of maleic acid, followed by hydrolysis ... 

L-Malic and citric acids are the major organic acids of fruits (Table 18.13). Malic acid is predominant in pomme and stone fruits, while citric acid is most abundant in berries, citrus and tropical fruits. (2R 3R)-Tartaric acid occurs only in grapes. Many other acids, including the acids in the citric acid cycle, occur only in low amounts. Examples are cis-aconitic, succinic, pyruvic, citramalic, fumaric, glyceric, glycolic, glyoxylic, isocitric, lactic, oxalacetic, oxalic and 2-oxoglutaric acids. In fruit juices, the ratio of citric acid to isocitric acid (examples in Table 18.14) serves as an indicator of dilution with an aqueous solution of citric acid. 

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