Methyl maleate, preparation

Unfortunately this ingeneous mechanism remains speculative since there is some doubt as to the identity of some of the labelled compounds. Thus, Mufti and Poller were unable to repeat the preparation of dibutyl tin bis (methyl maleate) but obtained instead dibutylchlorotin methyl maleate (93). Also there was no clear indication of either the chemical purity or the radiochemical purity (see Section 5 c) of the compounds BuaSnY2 (94). 

The enzyme aconitase catalyzes the isomerization of citric acid to isocitric acid via the intermediate cis-aconitic acid (Scheme 46), and various attempts have been made to model this reaction. The cobalt Ill) complexes derived from methyl maleate (171) and methyl fumarate (172) have been prepared to study intramolecular attack by coordinated hydroxide on the alkene. Generation of the hydroxo species of the maleic acid complex leads to rapid cyclization to give the... 

A solution of N-(2-aminobenzvl)-1-phenyl-2-metKylaminoethanol-1 was prepared by the reaction of a-bromo-acetophenone and (2-nitrobenzyl)methylamine, followed by hydrogenation of the nitro group by means of nickei on diatomaceous earth at room temperature and reduction of the CO group by means of sodium borohydride. The intermediate thus produced was dissolved in 100 ml of methylene chloride and introduced dropwise into 125 ml of sulfuric acid at 10° to 15°C. After a short standing, the reaction mixture was poured onto ice and rendered alkaline by means of a sodium hydroxide solution. Dy extraction with ether, there was obtained 1,2,3,4-tetrahydro-2-methyl-4-phenyl-8-amino-iso-quinoline. The base is reacted with maleic acid to give the maleate melting point of the maleate 199° to 201°C (from ethanol). 

Pyrrolidines have been prepared by 1,3-dipolar cycloaddition of N-(benzyli-dene)trimethylsilylamine/TMSOf 20 and methyl acrylate, N-methylmaleimide, or dimethyl maleate [35]. More recently, methyl trans-3-cyanociruiamate 1479 was reacted with N-benzyl-N-(trimethylsilylmethyl)aminomethyl methyl ether 1480 and trifluoroacetic acid in CH2CI2 at 0°C and 24°C to afford, via 1481, the pyrrolidine derivative 1482 in high yield and MeOSiMe3 13a [35a] (Scheme 9.20). Several... 

Following are the percentage yields obtained in the preparation of other esters ethyl maleate, 73 ethyl salicylate, 70 ethyl oxalate, 80 ethyl benzoate, 92 methyl benzoate, 87. In the preparation of ethyl maleate troublesome emulsions were encountered in working up the product. Occasionally this hap-... 

Huisgen et al.165 prepared the methyl pyrido[l,2-u]pyrimidine-2-carboxylate (100) from tetrazolo[5,l-u]pyridine and dimethyl maleate or fumarate at 160 C. The reaction presumably proceeds via the intermediates (97-99). Compound 100 was also obtained from 2-aminopyridine and dimethyl acetylenedicarboxylate. 

Weather-resistant ABS can be obtained either by the incorporation of EVAc [Fukushima and Mitarai, 1971], or by replacing PB with EPDM, to obtain AES [Wefer, 1984, 1985, 1988]. Alternatively, blends of SAN with maleated EPDM and CPE may be used [JCim et al., 1994]. However, the non-weatherable styrenics are frequentiy prepared by dissolving an elastomer in methyl methacrylate, and either styrene or a-methylstyrene, then polymerizing them into methyl methacrylate-butadiene-styrene graft copolymers... 

The experimental procedure described here for the preparation of Ru(ti -methyl acrylate)(C0)4 is applicable to a variety of other olefins as manifested by the syntheses of Ru(Ti -olefin)(CO)4 complexes of, for example, dimethyl fumarate, dimethyl maleate, allyl acrylate, methyl vinyl ketone (3-butene-2-one), and acrylonitrile. ... 

Substituted nitrothiophenes serve as precursors for a variety of condensed thiophenes. The synthesis of thienopyrroles has been reviewed <85S143>. Treatment of (2-nitro-3-thienyl)methyl phenyl sulfone (497) with diethyl maleate in the presence of K2CO3 and 18-crown-6 gave the thienopyridine A -oxide (498) in 38% yield <92acs689>. The reaction apparently proceeds by Michael addition, followed by elimination of phenylsulfinate and cyclization. The starting material can be prepared by vicarious nucleophilic substitution discussed earlier. 

To a flask equipped with a condenser were added 10 mL dry toluene, 3.0 mmol acetic anhydride, 0.15 mL dimethyl maleate (1.27 mmol), and a catalytic amount of p-toluenesulfonic acid. Under argon, 100 mg 2,6-dichloro-4-[(phenyl-sulflnyl)methyl]nicotinaldehyde (0.32 mmol) in toluene was added to above solution, dropwise over a period of 10 min. After the addition was complete, the yellow mixture was refluxed for an additional hour. The reddish yellow solution was cooled and washed with saturated aqueous NaHC03 solution. The organic layer was concentrated and purified by preparative layer chromatography to give dimethyl l,3-dichloro-5-(phenylthio)isoquinoline-6,7-dicarboxylate, in a yield of 44% yield, m.p. 109-111°C. 

Crystallization. The crystallization procedure is taken from that described by Fujii et For crystallization experiments, the Sulfolobus sp. ferredoxin solution obtained from a preparative Sephadex G-50 gel filtration column (Amersham Pharmacia Biotech) is concentrated by pressure filtration through an Amicon YM3 or YMIO membrane at 4° and made to 5 mg/ml in 0.5 M Tris-maleate-NaOH buffer, pH 5.0, containing 1% 2-methyl-2,4-pentanediol. Crystals suitable for X-ray diffraction analysis are obtained by a batch method performed under aerobic conditions. Fine-powdered ammonium sulfate is slowly added to 300 p.1 of 5 mg/ml protein solution until the turbidity is observed to persist (1.9-2.1 M). The crystallization solution is stored at 37° in an incubator. Dark brown crystals with appropriate dimensions of 0.3 x 0.3 x 0.5 mm are obtained in 3-5 weeks. Fujii etaO reported that reproducibility of the crystallization is enhanced by seeding a drop of the mother liquor containing microcrystals into the crystallization solution just before the crystallization begins. 

Pindur and Haber explored the chemistry shown in equation 2 and synthesized several new cycloadducts (Scheme 7, 6-12) from IQD 4 [52], The observed regiochemistry with unsymmetrical dienophiles (methyl acrylate, nitrosoben-zene, l,l-bis(phenylsulfonyl)ethane, methyl vinyl sulfone, and methyl vinyl ketone) was low to modest, with the major isomer as predicted by simple FMO theory. However, dienophiles acrolein, propynoates, and diethyl maleate were unreactive relative to dimerization of IQD 4. Pindur and Meyer prepared several bis(tetrahydropyrrolo[3,4- ] carbazoles) by exposing IQDs (generated as shown in equation 2) to alkane-tethered bismaleimides [53]. In two... 

Ethoxy-4-methyloxaole has been used to form pyridoxine (MI-286, R = H). With maleic anhydride it gives an adduct that, on treatment with ethanolic hydrogen chloride, forms the products W-287 and XII-288 (R = R - Et) and a monoester (XII-288 R = Et, R = H or R = H, R = Et). The diethyl ester MI-288 is also formed from ethyl maleate or ethyl fumarate and 5-ethoxy-4-methyloxazole. Fumaronitrile and ethoxy-4inethyloxazol ve 4,5-dicyano-2-methyl-3-pyridinol, ° also a known precursor to pyridoxine. 5-Ethoxy 4-irethyloxaolesand 2-butene-1,4-diol give pyridoxine (XII-286, R = H), which is difficult to purify when prepared in this way (assay, 23%). 

Blended matrices of maleated natural rubber and poly(methyl methacrylate) were prepared by mechanical mixing, and the fractured surface morphology of... 

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