Acetylenedicarboxylic esters condensation with

Reaction of thione 276 (R = H) with diethyl acetylenedicarboxylate in acetic acid or ethanol similarly gives both thiazolidinone (277) and thiazinone (278) as expected (79TL53) (Scheme 67). Condensation of 276 (R = Me, Cl, NO2, CO2H) and 280 with acetylenedicarboxylic esters gives a cyclized product in each case for which respective thiazolidinone structures 279 and 281 were assigned (77M11). This work warrants reinves-... 

Condensation of alkynes with carboxylic acids. Addition of RC(X)H to alky-nes forms enol carboxylates. On the other hand, heterocyclization occurs with acetylenedicarboxylic esters. ... 

From Oxathiazolones (Type B).—3-Phenyl-l,2,4-oxathiazol-5-one (17) is decomposed thermally to benzonitrile and sulphur, but condenses with activated dipolarophiles to yield 1,3-dipolar adducts that may arise from the intermediate benzonitrile sulphide (18). Thus, interaction of the oxathiazolone (17) and dimethyl acetylenedicarboxylate in chlorobenzene at 130 °C produces dimethyl 3-phenylisothiazole-4,5-dicarboxylate (19) in excellent yield. The use of ethyl propiolate (HC=CCOaEt) similarly affords the expected isomeric esters (20) and (21), each in 35% yield. The... 

The structure of the products of the condensation of thiourea or 1,3-disubstituted thioureas with acetylenedicarboxylate esters has been in dispute (see these Reports, Vol. 2, pp. 617, 760). The compounds have now been shown, by X-ray studies and chemical evidence, to be 2-imino-4-thiazolidinones (194), and not the six-membered alternatives. Hydrolysis of... 

Dimethyl acetylenedicarboxylate and the oxindole anion gave 295 (R = H), which was hydrogenated to 296,185 but oxindole with DMAD at 200° gave the furan 297,186 clearly derived by self-condensation of the ester, and the benzazepine 298 the structure and origin of which require further investigation. 

Approaches that represent a type (ii) synthesis of 277-pyran-2-ones include the self-condensation of 1,3-dicarbonyl compounds, the reaction of cyclopropanones with pyridinium enolbetaines and the reaction of activated methylene groups with acetylenic esters <1984CHEC, 1996CHEC-II>. 4-Perfluoroalkyl-6-aryl-pyran-2-ones are formed by the reaction of the phosphonium salts 631 with 2-perfluoroalkynoates (Equation 254) <1999JFC(95)135, 1998JFC(91)99>. Dimedone reacts with dimethyl acetylenedicarboxylate to afford the pyran-2-one 632 in excellent yield (Equation 255) <2003PS2627>. 

Condensations of chloroacetyl chloride (and similar compounds) with substituted ethylenediamines to give 1,4-disubstituted piperazin-2-ones have been described, and a number of 4-alkyl(or aralkyl)- -arylpiperazin-2-ones has been prepared either by catalytic debenzylation or pyrolytic debenzylation (or demethylation) of I,l-dialkyl(or l,l-diaralkyl)-3-oxo-4-arylpiperazinium halides (1609). 3-Ethoxy-carbonylmethylene-6-methylpiperazin-2-one has been synthesized by the reaction of diethyl acetylenedicarboxylate with propylenediamine (1610), and treatment of diethyl fumarate with propylenediamine has been shown to give 3-ethoxycarbonyl-methyl-6-methylpiperazin-2-one, also prepared from the diethyl ester of N- 2 -hydroxyiminopropyl)aspartic acid (84) (1611). 

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... 

Huisgen and Herbig condensed A -benzylphenylazomethine (X-18) with two moles of dimethyl acetylenedicarboxylate to obtain the corresponding 1,2-dihydropyridinetetracarboxylic acid ester (X-19). Oxidation with bromine afforded tetramethyl 2-phenylpyridine 3,4,5,6-tetracarboxylate (X-20). 

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