Dimethyl L -tartrate

5b) gave higher enantioselectivities than the corresponding (S,S) isomer (2-5a). 

Acyclic substrates were also investigated and promising results were obtained with tram -4-phenylbut-3-en-2-one (eq 6). 

Related Reagents. Phosphinoxazolines (PHOX ligands), BINAP, chiraphos, bisoxazolines. 

Pretot, R. Lloyd-Jones, G. C. Pfaltz, A. Pure Appl. Chem. 1998, 70, 1035. 

Jonathan A. Medlock Andreas Pfaltz University of Basel, Switzerland 

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Monoalkylation of a vic-glycol.1 Selective monoalkylation or monoacylation of the vic-glycol group of dimethyl L-tartrate is possible by conversion to the O-stannylene acetal (1) by reaction with dibutyltin oxide. The acetal is converted selectively to a mono derivative (3) by reaction with an alkyl halide or acyl chloride (excess) and CsF (about 2 equiv.). KF or Bu4NF are less effective than CsF. 

Dimethyl L-tartrate (17.8 g. 0.1 mol) and SF4 (43 g, 0.4 mol) were kept in a stainless steel cylinder at 20 C for 2 h. Volatile products were removed and the liquid from the cylinder was stirred in a polyethylene flask with NaF in CH2C12 for 3 h. The mixture was Filtered, the solvent removed and the residue vacuum distilled yield 17.8g (98%) bp 110-112 C/6Torr. 

The reaction of diethyl tartrate with sulfur tetrafluonde at 25 °C results in replacement of one hydroxyl group, whereas at 100 °C, both hydroxyl groups are replaced by fluonne to form a,a -difluorosuccmate [7(52] The stereochemical outcome of the fluorination of tartrate esters is retention of configuration at one of the chiral carbon atoms and inversion of configuration at the second chiral center [163,164, 165] Thus, treatment of dimethyl (+)-L-tartrate with sulfur tetrafluonde gives dimethyl meso-a,a difluorosuccinate as the final product [163, 164], whereas dimethyl meso tartrate is converted into a racemic mixture of D- and L-a,a -difluorosuccinates [765] (equation 80)... 

The stereoselective synthesis of (+)-polyoxin J is accomplished by Gosh in 24 steps and 3 % overall yield. The key intermediates are protected thymine polyoxin C 8 and the 5-Ocarbamoyl polyoxamic acid 2, which were synthesized from D-ribose and dimethyl L-tartrate. Key steps are two different epoxidation reactions, one carried out with MCPBA and the other under Sharpless conditions with the D-(-)-tartrate. Both epoxides are opened with diisopropoxytitanium diazide. The coupling of the two fragments was realized with the BOP reagent 37. This synthesis provides an easy access to the synthesis of various (+)-polyoxin J analogs for biological evaluation. 

Fig. 16.—Benzylation of dimethyl L-tartrate. Benzyl iodide gave 99% yield.69...

In an industrial asymmetric synthesis en route to the antiinflammatory agent naproxen, the dimethyl L-tartrate acetals of ethyl aryl ketones are brominated in high yield and selectivity to give the corresponding a-bromo derivatives. Subsequent stereospecific Ag -promoted 1,2-aryl migration provides the 2-alkyl-2-arylacetic acid after hydrolysis of the tartrate auxiliary, which is recovered (e.g. eq 4). 

The vicinal diol cyclic sulfate from dimethyl tartrate undergoes nucleophilic opening to give substituted malate esters., However, for this application diethyl and diisopropyl L-tartrates give superior yields and selectivities. The asymmetric cyclopropana-tion of the 1 -alkenylboronic ester derived from dimethyl L-tartrate (eq 5) is another example where other tartaric acid derivatives surpass the performance of dimethyl tartrate. ... 

Chiral Ligand for Asymmetric Catalysis. Dimethyl l-tartrate is a demonstrated chiral ligand for the Ti -catalyzed asymmetric epoxidation of allylic alcohols (Sharpless epoxidation), and the Zn -mediated asymmetric cyclo-propanation of allylic alcohols (Simmons-Smith reaction), see lodomethylzinc Iodide Enantioselectivities in these reactions... 

The synthesis of polytartaramides was first reported by Minoura and coworkers.79 During the 1970s, Ogata et a .80-81 described the polycondensation of tartaric acid itself or its 2,3-69-methylene derivative with diamines, by a variety of procedures. These authors also studied the copolymerizations of diethyl-L-tartrate with other diesters64 and reported that the rate of polymerization of dimethyl-L-tartrate with 1,6-diaminohexane in dimethyl sulfoxide at 60°C increased when the reactions were conducted in the presence of such polymer matrices as poly (vinyl pyrrolidone), pullulan, and poly (vinyl alcohol). The rate increased with increasing molecular weight of the matrix.82... 

One of the most potent frameworks for the synthesis of two contiguous stereochemically defined asymmetric centers is the chiral epoxy functionality. Prepared in molar-scale quantity from dimethyl L-tartrate (la), bromohydrin 860 is a shelf-storable solid that undergoes selective reduction at the a-hydroxy ester function with borane-dimethylsulfide complex in the presence of catalytic sodium borohydride to provide a 4 1 mixture of methyl (2S,3S)-2-bromo-3,4-dihydroxybutanoate (861) and methyl (2i, 3i )-3-bromo-2,4-dihydroxybutanoate (862). Without purification this mixture is treated with ert-butyldimethylsilylchloride and then exposed to sodium methoxide, which results in conversion to the single epoxide methyl (2i, 3iS)-4-( err-butyldimethylsilyloxy)-2,3-epoxybutanoate (863) in 95% yield and with 99% optical purity (Scheme 188). 

Chiral auxiliaries are particularly important in asymmetric synthesis. A bicyclic orthoester derived from dimethyl-L-tartrate (la) provides a novel auxiliary with useful applications. Treating la with phenylmagnesium bromide followed by reaction with methyl 2-methoxy-2,2-dichloroacetate (commercially available) affords in greater than 75% yield the methyl... 

Dimethyl L-(+)-tartrate has been converted in six steps and 63% overall yidd into 3-(p-methoxybenzyloxy)-l,2-0-(3-pentylidene)-L-//ireo-tetritol on a Idlogram scale. 

Polavarapu PL, Petrovic AG, Zhang P. Kramers-Kronig transformation of experimental electronic circular dichroism application to the analysis of optical rotatory dispersion in dimethyl-L-tartrate. Chirality 2006 18(9) 723-732. 

Acetals derived from Dimethyl L-Tartrate react with Me2BBr to generate a-bromo ethers which react further with cuprate reagents to give optically active secondary alcohol derivatives (eq 14). The alcohols may be liberated by treatment with Samarium(II) Iodide or by a straightforward sequence of reactions (mesylation and elimination to form an enol ether followed by exposure to methoxide in refluxing methanol). Selectivity is enhanced by the... 

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