Maleate, methyl

A ver promising reactivity of A-2-thiazoline-4-one has been found recently. 5-Aryl-A-2-thiazoline-4-one (190) gives the 1.3-dipolar cycloaddition product (191) with methyl fumarate and methyl maleate... 

Methylmagnesium bromide, 55, 63 Methyl maleate, 56, 63 Methyl mercaptan, 56, 73 Methyl 4-methoxybenzoate, 55, 40 Methyl 5-methyl-2-hexynoate, 55, 76 7V-Methyl-2-methylthiothiazolium iodide,... 

A sequential cycloaddition, tandem cycloreversion-cycloaddition process is more efficient than the direct cycloaddition, especially in case of aliphatic aldehydes, where the corresponding ylides are rather unstable. The cycloreversion strategy lowers the concentration of the free ylide in the reaction mixture and avoids side reactions such as self-condensation of this reactive species. In some cases, this tandem cycloreversion-cycloaddition sequence provides improved chemical yields without any loss of diastereoselectivity. For example, compound 476 treated with methyl fumarate, methyl maleate, and methyl acrylate provides acceptable yields of compounds 477-479 (Scheme 80) <2000S1170, 2002S1885>. 

Another example of the retention of volatile DA reagents is that of cyclopentadiene in a tandem retro-DA/DA prime reaction [15, 16, 38], This reaction type is the thermal decomposition of a DA adduct (A) and the generation of a diene (generally the initial diene) which is trapped in situ by a dienophile leading to a new adduct (B) [39]. Cyclopentadiene (22) (b.p. 42 °C) is generated by thermolysis of its dimer at approximately 160 °C [40]. An equimolar mixture of commercial crude dicyclopenta-diene (21) and dimethyl maleate was irradiated in accordance with the GS/MW process, in an open reactor, under 60 W incident power, for 4 min (8 x 30 s). The expected adduct 23 was isolated in 40% yield (Scheme 7.1). The isomeric composition of 23 (endo-endoIexo-exo = 65/35) was identical with that obtained under classical conditions from 22 and methyl maleate [41]. The overall yield of this tandem reaction can be increased from pure dimer 21 (61%) and the same tandem reaction has also been reported using ethyl maleate as dienophile [31]. 

In a similar way to the addition of zirconacyclopentadienes to DMAD, their addition to methyl maleate gives cydohexadiene derivatives. It is noteworthy that the two COOMe groups are cis in the starting material and trans to one another in the product, as shown in Eq. 2.63 [7k]. 

Monoiodination of a zirconacyclopentadiene with one equivalent of iodine followed by the addition of one equivalent of CuCl gives the dimer of the cyclobutadiene and the Diels—Alder product in the presence of methyl maleate. This indicates the formation of a l-iodo-l,3-dienyl copper compound and the subsequent elimination of Cul to give a cyclobutadiene equivalent. Direct reductive elimination of zirconacydopentadienes affording cyclobutadienes has not yet been observed. 

Methyl maleate 113 FALSE FALSE FALSE FALSE... 

Frye and his co-workers have continued their tracer investigations of PVC stabilisation (67) and claim to have synthesised (68) a whole series of compounds Bu2SnY2 with labelled butyl groups, labelled tin atoms or labelled Y groups where Y = oxo-octylthioglycollate, mono-methyl-maleate, 2-ethylhexanoate or /S-mercapto-propanoate. They sought to learn a) Do any chemical reactions occur between stabiliser and polymer b) If so what are their natures c) Do the reactions contribute to polymer stabilisation ... 

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),530 and various attempts have been made to model this reaction.21 The cobalt Ill) complexes derived from methyl maleate (171) and methyl fumarate (172) have been prepared531 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... 

THF, ethyl acetate, and methanol. In contrast, use of other chlorinated solvents, e.g. CCI4, and cyclohexane resulted in higher enantioselectivity, comparable with that for chloroform. The range of dienophile substrates was also studied. Replacing N-methylmaleimide by N-phenylmaleimide, in the presence of quinidine as a catalyst, also led to a good yield, although enantioselectivity was lower (20% ee compared with 61% ee). Much slower reaction rates were observed when methyl acrylate and methyl fumarate were used and enantioselectivity was low (0% ee for methyl acrylate and 30% ee for methyl fumarate). With methyl maleate as a dienophile no reaction was observed. Mechanistic studies were also conducted by Kagan et al. results were in accordance with a concerted [4+2]-cycloaddition process. 

The second type is oxidative dicarbonylation of acetylene with PdCb in benzene, which produces chlorides of maleic, fumaric and muconic acids [130], Methyl maleate (215), fumarate (216) and muconate (217) are obtained in MeOH containing thiourea by passing acetylene and oxygen in the presence of a catalytic amount of PdCb [131]. 

N1 - ERGOLINE-6-b ta-CARBOXAMIDE, 9,10-01DEHTORO-M-( (S )-2-HTDROXY-l-METHTLETHYL )-6-METHYL-, MALEATE (i i> (salt)... 

Chemical Name 2H,10H-Parazino[l,2-a]pyrrolo[2,l-c][l,4]benzodiazepine, l,3,4,14b-tetrahydro-2-methyl-, maleate (1 1)... 

Other dipolarophiles (yield, ratio 2-Ph 3-COOMe cis trans) methyl maleate (91%, 5 4) methyl fumarate (83%, 2 3) AMnethyl maleimide (85%, 1 2) methyl acrylate (83%, 5 4). 

The reaction of maleimide does not work in dichloromethane and gives polymers in HMPA or MeCN at room temperature. Itaconides are transformed quantitatively into citraconimides on treatment with traces of NEt3 in chloroform. 2,3-Dibenzoylpropene isomerizes rapidly into cis and trans 1,2-dibenzoylpropenes. Reactions with olefin need to be performed in refluxing solvent. However, reaction with methyl maleate does not appear to work at all. 

Diorthohydroxazo, 153 1,3-Dipolar cyclo additions, with dimethyl acetylenodicarboxylate, 426, 427 with methyl fumarate, 425,426 with methyl maleate, 425, 426 of A-2-thiazoline-4-one, 425, 426 Dipole moment, 2-ammothiazole. 29 2-imino-4-thiazoline, 29 A-4-thiazoline-2-one, 389 in A-4-thiazoline-2-thione, in relation with protomery, 379 Disproportionation, 107 2-Disubstituted aminothiazoles, 259-267... 

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