Dicarbomethoxy

The enamino ketone 5,5-dimethyl-l-pyrrolidinocyclohex-l-en-3-one (49) on treatment with dimethyl acetylenedicarboxylate and subsequent hydrolysis yielded 2,3-dicarbomethoxy-7,7-dimethyl- 1-hydroxy-5-oxo-1,3-cyclooctadiene (79). 

Ethyl 3-anilinocrotonate (82) undergoes reaction with dimethyl acetylene-dicarboxylate (57) with the formation of two products, ethyl 5-anilino-3,4-dicarbomethoxy-trfl s,cM-2,4-hexadienoate (83) and ethyl 5-anilino-3,4-dicarbomethoxy-ci5, cw-2,4-hexadienoate (84). 

The reaction of diacetylene with cyanic acid (HCNO) proceeds at room temperature in the presence of sulfuric acid in aqueous methanol to give 3-formyl-5,5 -diisoxazol-3 -aldoxime (85) and 3,3 -diformyl-5,5 -diisoxazoldioxime (86), whose oxidation with potassium permanganate followed by esterification results in 3,3 -dicarbomethoxy-5,5 -diisoxazoles (87) (59G598). 

An analogous sequence leads to the anthelmintic agent, etibendazole (50). Reaction of the benzophenone 47, which can be obtained by acylation of o-nitroaniline with g-fluorobenzoyl chloride, with ethylene glycol leads to acetal 48. Sequential reduction of the nitro group and cyclization of the resulting diamine (49) with N,N-dicarbomethoxy-S-methylthiourea gives the benzimidazole etibendazole (50) fl6]. 

Alder/retrograde Diels-Alder reaction sequence of a diaryl alkyne with a 3,6-dicarbomethoxy tetrazine. The resulting diazine (14) is then reduced, cleaved and cyclized with Zn/acetic acid to the 2,3,4,5-tetrasubstituted pyrrole (15), which is then N-alkylated with a-bromo-4-methoxyacetophenone to give a pentasubstituted pyrrole (16). The synthesis of lukianol A is completed by ester hydrolysis, decarboxylation, ring closure and deprotection. 

Thus we find that the reaction is a syn (suprafacial) addition with respect to both the diene and dienophile. The frontier orbitals involved shows that the reaction occurs by interaction of HOMO and LUMO. So there is no possibility of substituents to change their position. Substituents which are on the same side of the diene or dienophile will be cis on the newly formed ring as is seen between the reaction of dimethyl maleate (a cis dienophile) with 1,3 butadiene. The product formed is cis 4,5 dicarbomethoxy cyclohexane. 

A commercially available product is Pigment Yellow 155, a yellow pigment which is prepared by coupling the diazonium salt of 1 -amino-2,5-dicarbomethoxy-benzene onto the bifunctional coupling component 1,4-bisacetoacetylaminoben-zene [10] ... 

Crawford and Raap generated A,Af -dicarboalkoxy-Af,Af -dialkoxyhydrazines (212, = alkoxyl) in good yields using AgiO in diethyl ether. Af,Af -Dicarbomethoxy-A,Af -dimethoxyhydrazine was also prepared by oxidation of the A-chloro-A-methoxy-nrethane (213, X = Cl, R = Me, R = MeO) with triethylamine in methanol . 

In the reaction of o-azidoaniline with DMAD, it has been observed that both the amino and azido groups participate, giving rise to dimethyl 2-(4,5-dicarbomethoxy-l,2,3-triazol-l-yl)anilinofumarate (55) [Eq. (15)]. ... 

Krespan and McKusick have studied the addition reaction of dithietenes to various oleflnes and acetylenes. Thus, the reaction of 3,4-bis(trifluoromethyl)-l,2-dithiete (378) with DMAD gives a dithiin derivative (379), which loses sulfur on heating to give 2,5-dicarbomethoxy-4,5-bis(trifluoromethyl)thiophene (380) [Eq. (57)]. 

The reaction of a cyclic sulfonium ylide such as dimethylsulfonium-2-oxocyclohexylide (411) with DMAD gives rise to a ring-expanded product, namely, dimethylsulfonium-2,3-dicarbomethoxy-4-oxo-2-cyclooctenylide (414), probably through the intermediates 412 and 413 (Scheme 65). By carrying out the reaction in benzene, it was possible to isolate a compound assumed to be 413, which was subsequently transformed in polar solvents to 414. The reaction of an andogous ylide... 

Dicarbadodecaborane, preparation and structure of, 5 342-343 Dicarbomethoxy acetylene, 45 48, 49 Dicarbon decaboranes, 26 85 base degradation, 26 90 bonding, 26 62 dianions, 26 78-79 reaction with Lewis bases, 26 85 1,2-Dicarbonic acid dichlorides, 33 300 Dicarbon nonaborane anion, oxidative coupling, 26 73... 

Divalent metal ions, reversible binding, 38 153 Dixenon cation, 46 68 Dizinc enzymes, 40 351-354 DMA, see Dicarbomethoxy acetylene DMAD complexes, see Dicarboxymethoxy dithiolene complexes DMAE, see Dimethylarsinoylethanol DMF, reduction potentials, 33 57 DMSO, see Dimethylsulfoxide DNA... 

N,N Dicarbometboxy ethylenediamine [called N.N Dicarbomethoxy-athylendiamin Athylen-diurethylan or a./3-Bis(carbomethoxy-amino)-athan in Get],... 

The esters of l,3-dicarboxy-4-quinolizones show a tendency to undergo ester interchange on treatment with sodium alkoxides. For example, l,3-dicarbethoxy-4-quinolizone on treatment with sodium methoxide in methanol affords the corresponding dicarbomethoxy derivative in high yield.27 On treatment of the latter with sodium ethoxide, the original dicarbethoxy derivative is obtained. A similar observation was also made with the l-carbethoxy-3-nitro-4-quino-lizone as outlined in Scheme II. 

A related entry to the 1,7-phenanthroline ring system involves reaction of m-phenylenediamine with dimethyl acetylenedicarboxylate in methanol at ambient temperature.177 This affords the intermediate bis-fumarate which cyclizes in diphenyl ether at 250° giving, in 95% yield, 2,8-dicarbomethoxy-4,10-dihydroxy-1,7-phenanthroline. The angular... 

When l-benzoyl-2-phenyl-4,8-diazapentalene (8) was treated with dimethyl acetylenedicarboxylate under dehydrogenating conditions, 1-phenyl-2-benzoyl-5,6-dicarbomethoxy-2a-azacycl[2,2,2]azine (9a) was... 

The characteristics of the 1,3-dipolar cycloaddition mechanism of azides and other 1,3-dipoles (such as diazoalkanes, azo-methine imines, nitrones, nitrile imines, nitrile oxides) have been described in detail by Huisgen.191 19 According to the author, the addition of a 1,3-dipole (a b c) to a dipolarophile (d e) occurs by a concerted mechanism in which the two new a bonds are formed simultaneously although not necessarily at equal rates (32). As a consequence, a stereoselective cis addition is observed. Thus, the addition of p-methoxyphenyl azide to dimethyl fiynarate (33) yields l-(p-methoxyphenyl)-4,5-froiw-dicarbomethoxy-AMriazoline (34),194 and 4-nitrophenyl azide gives exclusively the respective cis-addition products 35 and 36 on addition to irons- and cis-propenyl propyl ether.196... 

Acetylenic esters react with alkyl azides, aryl azides, carbo-alkoxy azides, and tosyl azide yielding triazoles in all cases studied.102-302-306 When dimethyl acetylenedicarboxylate (92) is the starting material, the 1-substituted 4,5-dicarbomethoxy-1,2,3-triazoles 93 are obtained. 

The dicarboxy acids from the diene substrates were characterized functionally by chromatographic, elemental, and mass spectral analyses as 2. The dicarbomethoxy esters from carboxylated linoleate consist mainly of the 1,3-disubstituted 10,12- and 11,13-isomers, and 1,4-disub-stituted 9,12- and 10,13-isomers (Table II). The 1,3-dicarboxy acids (8,10 9,11 10,12 and 11,13) are the principal products of conjugated linoleate. Therefore, the 1,3-dicarboxy acids identified in the products of linoleate can arise from the conjugation process 1,4-diene — 1,3-diene. 

It is indeed unfortunate that the authors of Reference 110 chose to study the dicarbomethoxy derivative and the authors of Reference 111 chose the monocarbomethoxy derivative. Had the degree of substitution been the same, then equation 40 could have been rewritten... 

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