Dimethylacetylene dicarboxylate, addition

The dimer heated with dimethylacetylene dicarboxylate (DMAD) gives the adduct D, resulting from the addition to the tellurophene moiety of A. The adduct E resulting from the addition to the thiophene moiety of A was not detected. 

Indole reacts with dimethylacetylene dicarboxylate giving tetramethylcar-bazol-l,2,3,4-tetracarboxylate as a major product,formed via 384 (R = H, and/or geometric isomer) and then Diels-Alder addition and dehydrogenation. /V-Acetylindole undergoes an extraordinary double condensation and cyclization with methyl acrylate in the presence of palladium(II) acetate in acetic acid giving 9% of the dimethyl 9-acetylcarbazole-2,3-dicar-boxylate 393 as well as 394 and 395, the products of monosubstitution at the indole a and S-positions. ... 

Some aspects of the reactivity of the A-frames formed by Reaction 1 have been explored. Carbon monoxide and sulfur dioxide are readily lost from the respective adducts upon mild heating or exposure to vacuum. The insertions of isocyanides or sulfur have not been reversed. However the oxidation of Pd2(dpm)2(/Lt-S)Cl2 to Pd2(dpm)2-(/x-S02)Cl2 can be effected by using m-chloroperbenzoic acid as oxidant. Acetylene addition is photoreversible photolysis of Pd2(dpm)2-(/Lt-C2 C02CH3 2)C12 forms dimethylacetylene dicarboxylate and Pd2(dpm)2Cl2 (14). Pd2(dpm)2X2 is a catalyst for converting dimethyl-acetylene dicarboxylate into hexamethyl mellitate, and Pd2(dpm)2-(/it-C2 C02CH3 2)X2, which forms during the reaction, is presumed to be an intermediate. 

An alternative synthesis of 295 involves (175) the addition of diisoamyl-lithium cuprate to dimethylacetylene dicarboxylate. The major product (89%) was the required 295 together with some 297. The mixture was separated by chromatography. 

The products derived from guanidines show aromatic reactivity. They are strongly nucleophilic and may be brominated and methylated in the heterocyclic ring. Reaction occurs with dimethylacetylene dicarboxylate to form the eight-membered insertion product 85. However, this is possibly produced by a two-step process involving electrophilic substitution of the heteroring rather than direct Diels-Alder addition, and this proposal is supported by the simultaneous formation of the substitution product 86. 

Thiazoles, addition with dimethylacetylene dicarboxylate, 95 alkylation, 101... 

Stereoselective Additions of Phenols to DMAD. Phenols are prone to add on activated acetylenic compounds such as dimethylacetylene dicarboxylate (DMAD) [Eq. (20)]. 

Aromatization of the Diels-Alder adduct 303, obtained by addition of dimethylacetylene dicarboxylate to the 2-]8-D-ribofuranosylfuran 49, gave the 6-hydroxy-3-)8-D-ribofuranosylphthalate ester 304, which was O-... 

The classic Diels-Alder reaction continues to be applied to steroidal dienes and has been used to prepare benzene-fused compounds (277) (from 6-methylene testosterone ), and (278) and (279) [from the furano-steroid (217) ] and adducts between A -dienes and methyl acrylate, hexafluorobut-2-yne, dimethylacetylene dicarboxylate, and methyl propiolate have been obtained. In this last reaction the mono-adduct (280) was accompanied by a diadduct, assigned the structure (281), which arises from homo-conjugate Diels-Alder addition and which appears to be the first example of homo-conjugate addition to a substituted bicyclo[2,2,l]heptadiene. The diadduct was also obtained in good yield by treatment of the mono-adduct with more methyl propiolate. 

These observations support the view that the protonation occurs by initial oxidative addition at the metal atom and subsequent transfer of hydrogen to the coordinated alkyne which is argued on the basis of theory as well as experiment . In fact, the reaction of CH3COOH with (Ph3P)2Pt(DMA) (DMA = dimethylacetylene dicarboxylate) in the presence of PPh3 proceeds by addition of triphenylphosphonium acetate across the acetylenic triple bond ... 

Crank and Kahn reported a rare example of an isolable Diels-Alder adduct from the reaction of an oxazole with an acetylene in 1985. Thus 2-aminooxazole reacted with dimethylacetylene dicarboxylate to give a mixture of the cycloadduct 159 in 44% yield together with the bicyclic Michael addition product 160 in 16% yield... 

Pyridon-l-yl fumarates (XII-707), products of addition of 5,6-dimethyl-2-pyridone to dimethylacetylene dicarboxylates are rapidly saponified in cold aqueous alkali to the acids (XII-708), presumably by an intramolecular catalysis involving the pyridone oxygen. ... 

Sonication facilitates Diels-Alder reaction. Therefore, the addition of dimethylacetylene dicarboxylate to furan in water at 22-45 °C gives quantitative yield of the adduct (Scheme 23). 

Three rotameric forms of (26) have been isolated at room temperature. In fact Diels Alder addition of dimethylacetylene dicarboxylate to 2,3-dichloro-9-(l,l-dimethyl-2-phenylethyl)anthracene produces only the ap-rotamer (26). The other rotamers can be isolated by thermal equilibrium at 150 °C and subsequent chromatographic separation. Reaction of benzyne with the above anthracene yields only the d,/-triptycene derivative, and 4,5-dichlorobenzyne addition to 9-(l,l-dimethyl-2-phenylethyl)-... 

Figure 4 Experimental facial selectivity in the addition of three species to a cage diene. The structures include maleic anhydride (left), dimethylacetylene dicarboxylate (center), and iY-phenyltriazo-line dione (right)...

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