Dimethyl- -malate

The diastereoselective alkylation of dialkyl malates has been frequently used in the past [65]. However, according to the original procedure [63] (dialkyl malate, base, -78 -20 °C, then -78 °C, electrophile, then -78 0 °C, 16 h), the alkylation proceeded in average yields of about 50-60% and in diastereoselectivities in the range of 9 1 anti / syn. In our hands, application of this procedure to the reaction of benzyl bromide 23 with dimethyl malate 106 produced the alkylated compounds in only 20% yield. The yield of the alkylation was easily improved (>75%) when the ester was deprotonated with LHMDS in the presence of the electrophile at -78 °C and the reaction mixture was allowed to warm to 10 °C (Scheme 26 and Table 2). 

Dimethyl malate presents two ester functions a and p with respect to a hydroxy group, and PLE is able to regioselectively discriminate between these two moieties. ... 

Figure 1.13 GC analysis of organic acid methyl esters in a) standard solution, b) Chardonnay wine, c) Asti sparkling wine. 1. methyl lactate, 2. dimethyl succinate, 3. dimethyl maleate (i.s.), 4. dimethyl malate, 5. dimethyl tartrate, 6. trimethyl citrate. Chromatographic conditions poly(ethylene) glycol fused silica capillary column (30m x 0,25mm 0.25 xm), injector and detector temperature 250°C, flame ionization detector. Oven program 2min at 50 °C, from 50 to 200 °C at rate 4°C/min, 200°C isotherm for lOmin (Di Stefano and Bruno, 1983)...

The copper-mediated O-alkylation of alcohols with It, I i affords a mixture of alkyl ethers and aldehydes derived from the R group [286]. Dimethyl malate can be O-phenylated by combined use of PhsBi and OXONE in the presence of copper(II) pivalate (Scheme 14.138) [287]. The 0-phenylation of phenols with PhjBi proceeds smoothly in the presence of Cu(OAc)2 and EtjN [281a]. 

Other issues stereochemistry for OH on side chain was determined as R by conversion of the side chain to dimethyl malate. Total synthesis of spirastrellolide A methyl ester has been achieved. 

Butanedioic acid, hydroxy-, dimethyl ester (dimethyl malate malic acid dimethyl ester H3C-OOC-CHOH-CH2-COO-CH3 Butanedioic acid, hydroxy-, dipotassium salt KOOC-CHOH-CH2-COOK Butanedioic acid, (hydroxymethylene)-Butanedioic add, 2-hydroxv-2-(1-methylethyl)-Butarredioic add, 2,3-dihydroxy- tartaric acid HOOC-CHOH-CHOH-COOH... 

Triol 370 can also be prepared by reduction of EE-protected dimethyl malate 9a [14,15] or diethyl malate 9b [16] to give (5)-2-(l-ethoxyethoxy)-1,4-butanediol (371) in high yield. Deprotection under acidic conditions then furnishes 370 (Scheme 49). Cyclization of 370 (obtained by this route) under acidic conditions results in the formation of ( S)-( + )-3-... 

The shortest synthesis of dimethyl (/ )-malate (203) is a two-step process in which 889, upon treatment with thiocarbonyldiimidazole, is converted to thionocarbonate 898, which is then reduced with tri- -butyltin hydride to optically pure 203 in 67% overall yield [200]. 

Regio- and Diastereoselective Hydrolysis. Regiospecific hydrolysis of dimethyl malate at the 1-position could be effected with PLE as catalyst (Scheme 2.23) [209], Similarly, hydrolysis of an exo/endo-mixture of diethyl dicarboxylates with a bicyclo[2.2.1]heptane framework occurred only on the less hindered exo-position [210] leaving the endo-ester untouched, thus allowing a facile separation of the two positional isomers in a diastereomeric mixture. 

Dimethyl 3,4-0-isopropylidene-2,5-di-0-methyl-D-glucajate, G-241 Dimethyl 3,4-0-isopropylidene-i>glucarate, G-241 Dimethyl malate, M-6 Dimetl l tartrate, T-12... 

The absolute configuration of eldanolide, the pheromone from the wing glands of the male African sugar-cane borer, has been determined by a chiral synthesis of both of its enantiomers. (-t-)-Pantolactone (141) has been synthesized (in 40% yield) by a short sequence from (—)-(5 )-dimethyl malate. 1,2-0-Isopropyl-idene-D-glyceraldehyde is a useful chiral starting material for the synthesis of butyrolactones such as (142). The keto-lactone (143) is a useful intermediate in the synthesis of (+)-D-pantothenic acid it is prepared from readily available starting materials. ... 

Fig. 3.1 Chromatogram of extracted acids as their methyl esters prepared using boron trifluoride/methanol separated on a 3 m (0.0025 m i.d.) stainless-steel column packed with 5 per cent di(ethylene glycol) adipate on Chromosorb W (AW, DMCS, 100-120 mesh) using temperature programming from 60°C to 185°C at 7°C min, with an initial isothermal delay of 6 min and a final delay at 185°C until elution of trimethyl citrate. Peak identifications are 1, position of methyl pyruvate 2, methyl lactate 3, methyl-2,2-dimethoxypropionate 4, dimethyl fumarate 5, dimethyl succinate 6, methyl laurate (internal standard) 7, dimethyl malate 8, trimethyl citrate. (Redrawn with modifications from Hautala and Weaver, 1969)...

Fig. 3.4 Chromatogram of methyl esters obtained from a solution of pure adds and salts, separated on a 6 ft (0.004 m i.d.) glass column packed with 12.5 per cent di(ethylene glyclol) succinate on AW Chromosorb W (45-60 mesh), using temperature programming as follows 80°C for 1 min, 80-100 C at 2.9°C min S 100-133°C at 4.7 C min S 133 220°C at 4.8°C min and 220°C for 2.5 min. Peak identifications are 1, solvent 2, methyl pyruvate 3, methyl lactate 4, methyl 2,2-dimethoxypropionate 5, dimethyl-fumarate 6, methyl benzoate 7, dimethyl succinate 8, methyl laurate 9, dimethyl malate 10, dimethyl 2-ketoglutarate 11, dimethyl 2,2-dimethoxyglutarate 12, trimethyl citrate. (Redrawn with modifications from Zaura and Metcoff, 1969)...

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