Tartrate, dimethyl

The (R)-(+)-chiral 1,4-diol 17b was easily prepared from L-(+)-dimethyl tartrate. Dimethyl tartrate was converted to the corresponding phenylethylidene derivative by treatment with 1,1-dimethoxy-l-phenylethane and cat. p-toluenesulfonic acid in refluxing benzene, followed by conversion to the diol 17b with excess phenylmagnesium bromide. The diol was purified by column chromatography on silica gel (hexane ethyl acetate =5 1), and recrystalization from a mixture of hexane and 2-propanol. 

Figure 1. VCD in the OH-stretching region of (—)-(2S,3S)-dimethyl tartrate, 0.01 M in CCl, at three temperatures. Sample path length 0.48 cm, time constant 10 s, resolution 16 cm. (Reproduced with permission from ref. 51. Copyright 1980 American Chemical Society.)...

Investigation of template poly condensation kinetics has only been studied within a very narrow scope. Polymerization of dimethyl tartrate with hexamethylene diamine was found to be enhanced by using as a template poly(vinyl pyrrolidone), poly(2-vinyl pyridine), or polysaccharides and poly(vinyl alcohol), poly(4-vinyl pyridine). In this case, the template can be treated as a catalyst. No information exists on the influence of the template on the order of reaction. The increase in molecular weight of the polymerization product by the template can be induced by a shift of equilibrium or by an increase in the reaction rate. A similar increase in the reaction rate was observed when poly(4-vi-nyl pyridine) was used in the synthesis of poly(terephtalamides) activated by triphenyl phosphite.The authors suggested that a high molecular weight template was involved in the increase of the local concentration of the substrate (terephthalic acid) by adsorption and activation via N-phosphonium salt of poly(4- vinyl pyridine). 

Dimethyl tartrate, 124 of arenes Bromine, 170 of other substrates N-Bromosuccinimide, 49 Dimethyl tartrate, 124 Tetrabutylammonium tribromide, 287... 

Dimethyl sulfate, 239 Halo carbonyl compounds Camphor-10-sulfonic acid, 62 Dimethyl tartrate, 124 Halohydrins... 

Dichlorobis( 1 -phenylethoxy)-titanium(IV), 12 Diethyl tartrate, 276 2,2 -Dihydroxy-l, 1 -binaphthyl, 113 Diisopropyl tartrate, 276 Dimethyl tartrate, 124 Ephedrine, 298... 

Diethyl tartrate is the best tartaric acid derivative for enantioselective oxidation of thioethers. This finding was established for the asymmetric oxidation of methyl p-tolyl sulfide with cumene hydroperoxide, that is, 96% ee (DET) 87% ee (diisopropyl tartrate) 62% ee (dimethyl tartrate) [24] and 1.5% ee (bis A, V-dimethy I tart rami de, r-BuOOH as the oxidant) [17]. 

The dimethyl derivative, Compound 27, was prepared from racemic 1,2 dimethylsuccinic acid by first resolving with quinine (14, 15, 16), preparing the dimethyl ester, and then proceeding exactly by the same sequence used for DIOP from dimethyl tartrate (7). Table VI gives melting points and rotations of the compounds in Table III. 

The known allylic alcohol 9 derived from protected dimethyl tartrate is exposed to Sharpless asymmetric epoxidation conditions with (-)-diethyl D-tartrate. The reaction yields exclusively the anti epoxide 10 in 77 % yield. In contrast to the above mentioned epoxidation of the ribose derived allylic alcohol, in this case epoxidation of 9 with MCPBA at 0 °C resulted in a 65 35 mixture of syn/anti diastereomers. The Sharpless epoxidation of primary and secondary allylic alcohols discovered in 1980 is a powerful reagent-controlled reaction.12 The use of titanium(IV) tetraisopropoxide as catalyst, tert-butylhydro-peroxide as oxidant, and an enantiopure dialkyl tartrate as chiral auxiliary accomplishes the epoxidation of allylic alcohols with excellent stereoselectivity. If the reaction is kept absolutely dry, catalytic amounts of the dialkyl tartrate(titanium)(IV) complex are sufficient. 

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