Dimethyl acetylenedicarboxylate, reaction with

A few years after this initial report, Acheson and Foxton5 reinvestigated some of Letsinger s work and showed that the dimethyl acetylenedicarboxylate reaction with pyridazine was very solvent dependent. In a... 

Reaction of dimethyl acetylenedicarboxylate (DMAD) with extremely unstable mesomeric betaine 96, generated in situ from 95, gives in 30-36% yield of a 1 2 adduct, the structure of which was originally determined as 97 <1978CL1093>. However, a more recent reinvestigation based on the H and 13C NMR spectroscopy shows that the actual product is pyrazolo[l,5- ]azepine 98, formed probably by mechanism shown in Scheme 6 <1995JCM338>. 

Dimethyl acetylenedicarboxylate combines with itself in several ways to give compounds which have been reported occasionally as unexplained products (e.g., 16)17 from reactions of the esters with other... 

Attack at the heteroatoms was observed in the reactions of (1) and (2) with dimethyl acetylenedicarboxylate and with benzyne (78JCS(P1)1006). Compound (2) behaves as a heterodiene toward the acetylene ester, producing the quinoxaline (25) and selenium. The diester (25) was obtained only in trace amounts from (1). These reactions, and the failure of (1) and (2) to react with maleic anhydride, contrast with the behavior of naphtho[2,3-c] [l,2,5]thiadiazole which reacts with maleic anhydride across the center ring (64TL3815). 

Such reactions occur readily with alkynic esters, but the products isolated are often complex. Thus, the initial Michael adduct of type 79 from pyridine with dimethyl acetylenedicarboxylate reacts with a second equivalent of alkynic diester to yield 80, and thence 81 and other products. Quinoline and isoquinoline react similarly. 

Treatment of the pyrido-pyrimidines (346) with pyrrolidine gives the 1,8-naph-thyridines (347) (Scheme 133). The meso-ionic oxazines (349) that are formed by the reaction of chloroformyl-ketens with 2-pyridone undergo cycloaddition reactions with dimethyl acetylenedicarboxylate or with phenyl isocyanate, followed by loss of carbon dioxide, to yield quinolizines (350) and pyrido-pyrimidines (348), respectively (Scheme 134). Pyrido-pyrimidines (352) also result from the cycloaddition of anils of type (351) to ethyl vinyl ether (Scheme 135)."""... 

Dimethyl acetylenedicarboxylate reacted with the S,N-ylide (146) slowly to give a 10% yield of the product (230). The initial reaction corresponds to a [6 + 2] cycloaddition which need not be concerted (Scheme 41). In addition to this mode, the normal [4 + 2] cycloaddition also took place, leading to dimethyl tetrachlorophthalate in 30% yield <87JCS(Pl)2659>. The S,C-ylide (139a) does not undergo any such cycloaddition with dimethyl acetylenedicarboxylate. 

The reaction of dimethyl acetylenedicarboxylate (DMAD) with fullerene Ceo in the presence of hexamethylphosphorous triamide (HMPT, 291) or hexaethylphosphorus triamide (HEPT, 292) produced fullerene ylides (293) and (294), as described by Chuang et al These ylide derivatives exhibited unusual electronic absorptions in the visible region (435-660 nm), likely due to the presence of the ylide moiety (Seheme 67). 

Dimethyl acetylenedicarboxylate (DMAD) (125) is a very special alkyne and undergoes interesting cyclotrimerization and co-cyclization reactions of its own using the poorly soluble polymeric palladacyclopentadiene complex (TCPC) 75 and its diazadiene stabilized complex 123 as precursors of Pd(0) catalysts, Cyclotrimerization of DMAD is catalyzed by 123[60], In addition to the hexa-substituted benzene 126, the cyclooctatetraene derivative 127 was obtained by the co-cyclization of trimethylsilylpropargyl alcohol with an excess of DMAD (125)[6l], Co-cyclization is possible with various alkenes. The naphthalene-tetracarboxylate 129 was obtained by the reaction of methoxyallene (128) with an excess of DMAD using the catalyst 123[62],... 

Like pyridines (334), thiazoles undergo addition reactions with dimethyl acetylenedicarboxylate leading to 2 1 molar adducts, the structure of which has been a matter of controversy (335-339). 

Dicyanoacetylene, 2-hiitynedinitri1e, is obtained from dimethyl acetylenedicarboxylate by ammonolysis to the diamide, which is dehydrated with phosphoms pentoxide (44). It bums in oxygen to give a flame with a temperature of 5260 K, the hottest flame temperature known (45). Alcohols and amines add readily to its acetylenic bond (46). It is a powerhil dienophile in the Diels-Alder reaction it adds to many dienes at room temperature, and at 180°C actually adds 1,4- to benzene to give the bicyclo adduct (7) [18341 -68-9] C QHgN2 (47). 

The reactions of pyrroles with dimethyl acetylenedicarboxylate (DMAD) have been extensively investigated. In the presence of a proton donor the Michael adducts (125) and (126) are formed. However, under aprotic conditions the reversible formation of the 1 1 Diels-Alder adduct (127) is an important reaction. In the case of the adduct from 1-methylpyrrole, reaction with a further molecule of DMAD can occur to give a dihydroindole (Scheme 48) (82H(19)1915). 

Few isothiazoles undergo simple cycloaddition reactions. 4-Nitroisothiazoles add to alkynes (see Section 4.17.7.4). With 5-thiones (84) and dimethyl acetylenedicarboxylate, addition to both sulfur atoms leads to 1,3-dithioles (85) (77SST(4)339, 80H(14)785, 81H(16)156, 81H(16)595). Isothiazol-3-one 1-oxide and the corresponding 1,1-dioxide give normal adducts with cyclopentadiene and anthracene (80MI41700), and saccharin forms simple 1 1 or 1 2 adducts with dimethyl acetylenedicarboxylate (72IJC(B)881). 

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