The reactivity of 2-vinylindoles with dimethyl acetylenedicarboxylate

The overall rates of reaction of 1-substltuted-1- (1-methyl-2-indolyl)ethenes with dimethyl acetylenedicarboxylate are considerably lower than those of the corresponding 2-vinyl- pyrroles. Steric interaction between the N-methyl group on the indole ring and the 1-substituent on the ethenyl group prevents the diene system adopting a coplanar $\text{cisoid}$ configuration and, thereby, inhibits the _π4 + _π2 cycloaddition reaction of the system with dimethyl acetylenedicarboxylate. Under such conditions, the indolylethene preferentially undergoes a Michael addition reaction at the 3-position. The _π4 + _π2 cycloaddition reaction is promoted at elevated temperatures. No evidence was found for a Cope rearrangement of the Michael adducts to give the dihydrocarbazole.     

Cycloaddition reactions of polyfluoroalkylthioncarboxylic acid derivatives with dimethyl acetylenedicarboxylate (DMAD)

Polyfluoroalkyldithiocarboxylates react with dimethyl acetylenedicarboxylate (DMAD) to give 2-polyfluoroalkyl-1,3-dithioles and/or 2-polyfluoroalkylidene-1,3-dithioles depending on the substituent at the thiolic sulfur atom and on the length of the polyfluoroalkyl chain. Amides of polyfluoroalkylthioncarboxylic acids with DMAD give 2-methoxy-2-polyfluoroalkyl-5-methoxycarbonylmethylene-thiazolidin-4-ones.     

Condensation of azomethines with dimethyl acetylenedicarboxylate

The condensation of dimethyl acetylenedicarboxylate with benzylidene- and cyclohexylideneaniline, as well as with cyclohexylidene-p-toluidine and cyclohexylidene-p-anisidine, under various conditions gave 11, 12, and 13 adducts. The structures of the isolated substances, which are formed as a result of the addition of the ester to the azomethines with subsequent 1,5-prototropic rearrangement (arylcyclohexenylvinylamines), as well as by cycloaddition (substituted dihydropyridines and spiro-cyclohexanedihydropyridines), are discussed.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 366–371, March, 1984.     

Three-component coupling reactions of isoquinolines, dimethyl acetylenedicarboxylate and indoles: a facile synthesis of 3-indolyl-1,2-dihydro-2-isoquinolinyl-2-butenedioate

A three-component coupling of isoquinolines, dimethyl acetylenedicarboxylate (DMAD) and indoles is achieved for the first time to produce dimethyl (E)-2-[1-(1H-3-indolyl)-1,2-dihydro-2-isoquinolinyl]-2-butenedioates in excellent yields and with high selectivity. The reaction proceeds smoothly at room temperature without a catalyst. Quinoline, DMAD and indole also undergo smooth coupling to furnish dimethyl (E)-2-[2-(1H-3-indolyl)-1,2-dihydro-1-quinolinyl]-2-butenedioate under similar conditions. This method is very useful to functionalize both indoles and aza-aromatic compounds in a one-pot operation.     

Microwave assisted condensation reactions of 2-aryl hydrazonopropanals with nucleophilic reagents and dimethyl acetylenedicarboxylate

The reaction of methyl ketones 1a-g with dimethylformamide dimethylacetal (DMFDMA) afforded the enaminones 2a-g, which were coupled with diazotized aromatic amines 3a,b to give the corresponding aryl hydrazones 6a-h. Condensation of compounds 6a-h with some aromatic heterocyclic amines afforded iminoarylhydrazones 9a-m. Enaminoazo compounds 12a,b could be obtained from condensation of 6c with secondary amines. The reaction of 6e,h with benzotriazolylacetone yielded 14a,b. Also, the reaction of 6a,b,d-f,h with glycine and hippuric acid in acetic anhydride afforded pyridazinone derivatives 17a-f. Synthesis of pyridazine carboxylic acid derivatives 22a,b from the reaction of 6b,e with dimethyl acetylenedicarboxylate (DMAD) in the presence of triphenylphosphine at room temperature is also reported. Most of these reactions were conducted under irradiation in a microwave oven in the absence of solvent in an attempt to improve the product yields and to reduce the reaction times.     

Reaction of substituted selenoureas with dimethyl acetylenedicarboxylate

Mono and 1,3-disubstituted selenoureas react with dimethyl acetylenedicarboxylate to give in high yield substituted 3,4-dihydro-4-oxo-2H-1,3-selenazines whose structures were established by speclroscopic methods.     

Synthesis of dimethyl 1,2-dihydroisoquinolines through the reaction of isoquinoline and dimethyl acetylenedicarboxylate in the presence of amides

Isoquinoline reacts smoothly with dimethyl acetylenedicarboxylate (DMAD) in the presence of amides to produce dimethyl 2-[1-[aryl(alkyl)carbonylamino]-2(1H)-isoquinolinyl]-2-butenedioates. Reaction of quinoline with DMAD in the presence of benzamide led to dimethyl 2-[1-[(phenylcarbonyl)amino]-2(1H)-quinolinyl]-2-butenedioate.     

A novel bicyclic phosphonium ylide from the reaction of a 1,2-dihydrophosphorin with dimethyl acetylenedicarboxylate.

The reaction of 1,2,5-triphenylphospholium fluorenylide with dimethyl acetylenedicarboxylate gives two 1:1 adducts, one of which is shown by X-ray analysis to have a novel 1-phosphabicyclo[3.2.1]octatriene structure.     

A quantum chemical study on the reaction of 1-aryl-1,2-dihydrophosphinine oxides with dimethyl acetylenedicarboxylate

A β-oxophosphorane/ylide (2a) and an oxaphosphete (3a), the product and the possible intermediate of an inverse Wittig type reaction of 1-(2,4,6-triisopropylphenyl-)1,2-dihydrophosphinine oxide with dimethyl acetylenedicarboxylate were studied by quantum chemical calculations. The reaction of the title reagents following either a traditional [4 + 2] cycloaddition protocol to afford phosphabicyclo[2.2.2]octadiene 5 or a novel route yielding eventually β-oxophosphorane/ylide 2 was evaluated by energy calculations. The mechanism for the formation of intermediate 3a₂ was refined by HF/6-31G* transition state calculations. Analysis of the HOMO-LUMO orbitals of the reagents justified the reactivity experienced.     

Reactions of 16e CpCo half-sandwich complexes containing a chelating 1,2-dicarba-closo-dodecaborane-1,2-dichalcogenolate ligand with ethynylferrocene and dimethyl acetylenedicarboxylate

The reaction of the 16e half-sandwich complex [CpCo(S2C2B10H10)] (1S; Cp: cyclopentadienyl) with ethynylferrocene in CH2Cl2 at ambient temperature leads to [CpCo(S2C2B10H9)-(CH2CFc)] (2S; Fc: ferrocenyl) and 1,2,4-triferrocenylbenzene. In 2S, B substitution occurs at the carborane cage in the position B3/B6 with the formation of a C-B bond. In the presence of the protic solvent MeOH, 2S loses a CpCo fragment to generate [(CH2CFc)(S2C2B10H9)] (3S). On the other hand, 2S can take a free CpCo fragment to form [(CpCo)2(S2C2B9H8)-(CHCFc)] (4S) containing a nido-C2B9 unit. In sharp contrast, [CpCo-(Se2C2B10H10)] (1Se) does not react with the alkyne in CH2Cl2, but in MeOH [(CHCFc)(Se2C2B10H10)] (5Se) is generated without the presence of a CpCo unit. The reaction of 1 with dimethyl acetylenedicarboxylate at ambient temperature leads to insertion compounds [CpCo(E2C2B10H10){(MeO2C)-C=C(CO2Me)}] (6S, E=S; 6 Se, E=Se). Upon heating, 6S rearranges to two geometrical isomers [CpCo(S2C2B10H9){(MeO2C)C=CH(CO2Me)}] (7S) and [CpCo(S2C2B10H9){(MeO2C)-CHC(CO2Me)}] (8S). In both, B-H functionalization takes place at the carborane cage in the position B3/B6, but 7S is a 16e complex with an olefinic unit in a Z configuration, and 8S is an 18e complex containing an alkyl B-CH group. Further treatment of 7 S with dimethyl acetylenedicarboxylate at ambient temperature affords two B-disubstituted complexes at the carborane cage in the positions of the B3 and B6 sites, that is, [CpCo(S2C2-B10H8){(MeO2C)C=CH(CO2Me)}2] (9S) and [CpCo(S2C2B10H8){(MeO2C)-CHC(CO2Me)}{(MeO2C)C=CH-(CO2Me)}] (10S). Compound 9S is a 16e complex with two olefinic units in E/E configurations, whereas 10S is an 18e species containing both an olefinic substituent and an alkyl B--CH unit. The reaction of 7S with methyl acetylenemonocarboxylate at ambient temperature leads to the sole 16e compound [CpCo(S2C2B10H8){CH=CH(CO2Me)}-{(MeO2C)C=CH(CO2Me)}] (11S). In contrast, 6Se does not rearrange. All new complexes 2S-4S, 5Se, 6Se, and 7S-11S were characterized by NMR spectroscopy (1H, 11B, 13C) and X-ray structural analyses were performed for 2S-4S, 5Se, 6Se, and 7S-9S.     

Novel annulation reactions of aryl methyl ketenes with zwitterions derived from dimethyl acetylenedicarboxylate and N-alkylimidazoles

[reaction: see text] A novel three-component annulation reaction involving N-alkylimidazoles, dimethyl acetylenedicarboxylate, and in situ generated aryl methyl ketenes leading to the synthesis of 6-vinyl-1,3a-diazapentalene derivatives is reported.     

Further study on 1,3-dialkylaminouracil with dimethyl acetylenedicarboxylate

On the treatment of 1,3-dialkyl-6-alkylaminouracil (1) with dimethyl acetylenedicarboxylate (DMAD), we were able to develop a new synthesis of deazapurine (pyrrolo[2,3-d]pyrimidine, 4) , and proposed the plausible mechanism for the formation of 3 and 4 from the adduct [dimethyl 2-(1,3-dialkyl-6-alkylamino-2,4-dioxopyrimidin-5-yl)fumarate, 2] of 1 with DMAD.