Acetylenedicarboxylic acid ester synthesis

Quinoxalinones result from the reaction of o-phenylenediamines and acetylenedicarboxylic acid, as exemplified by the synthesis of 3,6,7-trimethylquinoxalin-2-one (18) The corresponding condensation reactions with acetylenedicarboxylic acid esters yield 3-alkoxycarbonyl-methylenequinoxalin-2-ones, which on hydrolysis and rearrangement give... 

In the earliest examples of this approach, Fiesselmann studied acetylenic esters, including acetylenedicarboxylic acid esters, the former producing 5-substituted 3-hydroxythiophene-2-esters whilst the latter giving rise to 3-hydroxythiophene-2,5-dicarboxylic esters (Scheme 60) [90-92] (Later work used milder conditions for this synthesis [93]). The final ring closing condensation to produce the 3-hydroxythiophene-2-esters is of the Claisen type and one can envisage the first cyclic intermediate as 36 which tautomerises. 

The synthesis of the heterocyclic dendrimer 181 was based on the intermolecular 1,3-dipolar cycloaddition of the azide 180 with acetylenedicarboxylic acid and its esters (39) (Scheme 9.39). 

Acetylenedicarboxylic acid, dimethyl ESTER, 32, SS Acetylenic glycols, 39, 57 2- -Acetylphenylhydroquinone, 84,1 S-ACETYL-n-VALERIC ACID, 31, 3 Acid chlorides, 39, 19 synthesis of, 37, 69... 

Wittig synthesis followed by acetylenedicarboxylic ester synthesis of benzene rings via dihydrophthalic acids—cis-frans-Rearrangement s. 16, 977... 

This classification is illustrated in Scheme 317. Imidazole synthesis under this category is uncommon, as noted in CHEC(1984) and CHEC-II(1996). One example, in which secondary amino-AT-carbothioic acid (phenyl- -tolylimino-methyl)amides 1258 react with dimethyl acetylenedicarboxylate to form 4-aminoimidazoles 1259, has been reported. A reaction mechanism including the formation of a seven-membered cyclic intermediate followed by the extmsion of thioglyoxylic ester has been proposed (Scheme 318) <2004TL8945>. 

Many ring-fused imidazole derivatives have been synthesized by various methods. Domino Michael addition retro-ene reaction of 2-alkoxyiminoimidazolidines and acetylene carboxylates provided a synthesis of 2,3-dihydroimidazo[l,2-a]pyrimidin-5-(l//)-ones <05T5303>. A single step synthesis of 3,5-dialkyl-9-nitroimidazo[l,2-c]quinazolin-2(3//)-ones from simple carbonyl compounds, primary amines or amino acid methyl esters and 2-azido-5-nitrobenzonitrile has been published <05TL5778>. Diels-Alder reaction of azadienes and benzimidazole-4,7-diones afforded imidazo[4,5-g ]quinoline-4,9-dione derivatives <05EJ01903>. Reaction between isocyanides and dialkyl acetylenedicarboxylates in the presence of 4,5-diphenyl-l,3-dihydro-2//-imidazol-2-one provided a one-pot synthesis of 5//-imidazo[2,l-ft][l,3]oxazine derivatives <05T2645>. Microwave irradiation was employed in the synthesis of 1-ary 1-3-acetyl-1,4,5,6-... 

Alkyl, cycloalkyl, arylalkyl acids and their derivatives. A facile, diastereoselective synthesis of highly functionalized y-lactone phosphonate esters (76) has been achieved in the reaction of trifluoromethylated-1,3-diones with dimethyl acetylenedicarboxylates in the presence of triphenyl... 

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