Methyl succinate, reactions

Deng also showed that (DHQD)2AQN could catalyze the parallel KR (PKR) of a variety of monosubstituted succinic anhydrides via asymmetric alcoholysis [215]. The nature of the solvent was found to have a significant influence on the selectivity. Hence, increasing the size of the alcohol from methanol to ethanol resulted in increased levels of enantioselectivity, albeit with reduced reaction rates. In this context, 2,2,2-trifluoroethanol appeared to be the alcohol of choice as it allowed the ASD of 2-methyl succinic anhydride (58a) with a remarkable level of selectivity. Indeed, the use of (DHQD)2AQN (15 mol%) provided a mixture of two regioiso-meric hemiesters 59a and 60a in a 1 1 ratio with 93 and 80% ee respectively. 

Because the liquid phase enthalpy of formation of the corresponding t-butyl methyl succinate ester is available, —950.9 3.0 klmol", the enthalpy of reaction 16 can be calculated. The result, —72.8 3.9 kJ mol , is nearly the same as that for the esters and peresters above, —70.3 8.1 kJmol. ... 

The quinazolinone moiety (36-3) for the cardiotonic agent prindoxan (36-5) is formed by reaction of diamine (36-1) with carbonyl diimidazole (36-2). Friedel-Crafts acylation of the product with the half-acid chloride from methyl succinate gives the corresponding keto-ester (36-4). The pyridazinone (36-5) is then obtained by condensation of that product with hydrazine [38]. 

It might be anticipated that, if a racemic unsymmetrically substituted cyclic anhydride were to be used as a substrate for asymmetric alcoholysis, a KR would ensue. In fact, Deng has shown that for monosubstituted succinic anhydrides, because both carbonyl groups have comparable reactivity, what actually occurs on subjection to his (DHQD)2AQN-catalyzed asymmetric alcoholysis conditions, is a PKR [188]. Thus, the reaction of 2-methyl succinic anhydride (39a) with 2,2,2-trifluoroethanol (10 equiv.) in ether at —24 °C in the presence of (DHQD)2AQN (15 mol%) provided a mixture of two regioisomeric hemiesters... 

Ita-conic Acid.—There is, however, a third acid known of the same composition as the two preceding. It is called ita-conic acid and like the others is obtained from citric acid by distiUation. More than the two isomers just explained are not possible according to geometric isomerism. The isomerism, therefore, of this new acid with the other two must be explained in some other way and has been shown to be structural isomerism due to the different position of the double bond. We have spoken of the fact that both citra-conic and mesa-conic acids, by the addition of hydrogen, are converted into methyl succinic acid. This same result is obtained with ita-conic acid also as may be explained by the following reactions. 

Hydrogenation of methyl succinate obtained by the oxidative carboxyalkylation of etbylene by the following reactions ... 

The new 23-hydroxy-epimers of cholesterol have been prepared by boro-hydride reduction of the 23-ketone, and Grignard reactions on the cyanohydrin of pregnenolone acetate have been used to prepare both epimers of 20a,22-dihydroxycholesterol. Using optically pure half-esters of methyl succinic acid in Kolbe electrolytic coupling reactions with various bile acids the corresponding 25-d- and 25-L-cholestanoic acids have been prepared. ... 

In Section 31.6 we mentioned the enantioselective reduction of itaconic acid by a number of entrapped chiral organometallic catalysts [25]. A follow-up and major improvement of that study was reported by Volovych et al. [30]. These authors hydrogenated itaconic acid with sol-gel-entrapped Rh complexed with (2S,4S)-l-tert-butoxycarbonyl-4-diphenylphosphino-2-(diphe-nylphosphinomethyl)pyrrolidine catalyst in methanol solutions. The immobilization process was carried out with different sol-gel precursors TMOS, TEOS, triethoxyphenylsilane PhSi(OEt)3/TMOS, and trimethoxy (octyl)silane OcSi(OMe)3/TMOS. The choice of the precursor was found to influence the enantioselectivity and the rate of the reaction. The immobilized catalyst could be recovered and recycled several times under N2 atmosphere. About 90-99% ee was achieved for the hydrogenation of itaconic acid to (S)-(+)-2-methyl succinic acid. 

The emerging cyanopropyl radicals not only can initiate the polymerization reactions but may also recombine with the formation of dinitril tetra-methyl succinate or a corresponding ketenimine. 

With an activated C—C triple bond two successive additions can occur if the intermediate alkene is reactive enough. DMAD and 3,5-dimethylpyrazole give an initiaj fumarate (255) which reacts further at the other end to form regioselectively the succinates (256). On the other hand, methyl ethynyl ketone reacts twice at the same carbon atom with pyrazole to form 1,1-pyrazolylbutanone (258) (68ZC458). The probable intermediate, a pyrazolide vinylogue (257), can be prepared from methyl chlorovinyl ketone and pyrazole, in a reaction which is similar to acetylation (Section 4.04.2.1.3(x)). 

A basic ionic liquid, l-methyl-3-butylimidazolium hydroxide ([bmIm]OH) and l-butyl-3-methyl-methylimidazolium tetrafluoroborate ([bmim]BF4), has been introduced as a catalyst and reaction medium for the Markovnikov addition of imidazoles 116 to vinyl esters 115 under mild conditions to give imidazoesters 117 <06JOC3991 06TL1555>. A series of (nitroimidazolyl)succinic esters and diacids were prepared from the Michael-type addition of the nitroimidazole to the a,P-unsaturated ester <06S3859>. 

Dimethyl succinate derivatives 187 eliminate a molecule of methyl ethanoate upon heating to give 1,2,4-triazoles 188a-e in reasonable yield. The reaction also produces the corresponding triazines but these are readily separated from the desired triazoles (Equation 59 and Table 40) <2001EJM93>. 

DPP pigments are synthesized by reacting succinic ester with benzonitriles in the presence of alcoholate in the corresponding alcohol for base catalysis. Originally starting from sodium methylate/methanol an important step toward a significantly improved yield was achieved by reaction of succinic tert.-alkylester in sodium tert.-alkylalcoholate/tert.-alkylalcohol. 

Amine-terminated, G3 (PAMAM) dendrimer, (0.316 g 45.7 moles) was dissolved in anhydrous methyl sulfoxide (5 ml) in a 100 ml round-bottom flask flushed with dry nitrogen. After dendrimer had completely dissolved, succinic anhydride (Aldrich) (0.363 g 3.6 mmol) was added to the reaction mixture with vigorous stirring, and the mixture was allowed to react for 24 h at room temperature. The product solution was diluted with deionized water, transferred to 3500 MWCO dialysis tubing (Spectrum) and dialyzed against deionized water (18 Mil) for 3 d. The retentate solution was clarified by filtration through Whatman No. 1 filter paper, concentrated with a rotary evaporator, and lyophilized to yield a colorless powder (0.435 g, 94%). The product was analyzed by 13C-NMR, FT-IR, SEC and MALDI-MS. The analytical data were consistent with the expected carboxylic acid-terminated product. 

Though EM ratios are given for both reactions, the data are not independent. The EM s for the amide hydrolysis are based on a value (EM = 5.1 x 104 M) for the succinamic acid reaction which is assumed to be identical with that for the hydrolysis of monophenyl succinate monoanion. However, both sets of data show similar behaviour. The EM s for the rate processes, initially smaller by less then an order of magnitude than those for equilibrium anhydride formation, increase much less rapidly with increasing methyl substitution, so that the EM ratios decrease with increasing EM. 

Other alkali/alkaline earth metal iodides either cleave esters less efficiently or form insoluble carboxylate salts and are therefore not as effective as Lil. Addition of Li and l" compounds capable of forming Lil under reaction conditions works as well as initially charging Lil (Table IV). The acetaldehyde producing step. Equation 17, is carried out with the cobalt-based catalyst. Since the carboxylate half of the ester is not involved with the cobalt center, any methyl ester which can be cleaved by Lil should also show activity. We have found that methyl isobutyrate, dimethyl malonate, methyl propionate, and dimethyl succinate yield acetaldehyde and the corresponding carboxylic acids in high yield under the same conditions utilized with methyl acetate. 

Deaminase, adenosine, cattle, reaction prodnct with succinic anhydride, esters with polyethylene glycol mono-methyl ether [CAS] PEG-Adenosine Deaminase [SY]... 

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