Search results for "Acetylenedicarboxylate"
showing 10 items of 32 documents
Theoretical study on the mechanism of the domino reactions of tertiary α-cyano-enamines and dimethyl acetylenedicarboxylate
2001
Abstract The mechanisms of the domino reaction between dimethyl acetylenedicarboxylate, 1 , and 2-( N , N -dimethylamino)acrylonitrile, 2 , and these in presence of acrylonitrile have been theoretically studied using ab initio methods. These domino reactions comprise several pericyclic-type reactions. The geometrical and electronic analysis of the HF/6-31G ∗ transition structures and intermediates allows characterizing the processes that take place along these domino reactions. B3LYP/6-31G ∗ energetic results are in agreement with the experimental outcomes.
Theoretical Study on the Molecular Mechanism of the Domino Cycloadditions between Dimethyl Acetylenedicarboxylate and Naphthaleno- and Anthracenofura…
2001
AM1, B3LYP/6-31G//AM1, and B3LYP/6-31G computational studies were performed to select the reaction pathway controlling the reactions between dimethyl acetylenedicarboxylate (DMAD) and two furanophanes, naphthalenofuranophane and anthracenofuranophane. For these domino reactions, several pathways have been characterized on the potential energy surface corresponding to two consecutive cycloadditions. The first step corresponds to a [4 + 2] intermolecular cycloaddition of DMAD with the furan ring or with the naphthalene or anthracene ring of both furanophane systems to yield an oxabicyclo[2.2.1]heptadiene or a bicyclo[2.2.2]octadiene intermediate, respectively. The second step corresponds to […
ChemInform Abstract: Diels-Alder Reactions of Methyl- and π-Acceptor-Substituted 2- Vinylindoles with Dimethyl Acetylenedicarboxylate and Tetracyanoe…
2010
The Diels-Alder reactions of the 2-vinylindoles 1a-1d, which are now readily accessible, with dimethyl acetylenedicarboxylate and tetracyanoethylene give rise to the novel 1,2-dihydro- and 1,2,3,4-tetrahydrocarbazoles 2, 4, and 5 as well as the fully aromatized carbazoles 3. With regard to the product spectrum, the mechanistic rationale comprises a Diels-Alder step, formal 1,3-hydrogen shift, ene reaction, and dehydrogenation. Conformational aspects of the 1,2-dihydrocarbazoles 2b and 2c are also discussed.
Regiospecific and stereoselective ene reaction of the A-ring methylcyclohexene moiety of polycyclic terpenoid systems with dimethyl acetylenedicarbox…
2001
Polycyclic terpenoid compounds with a methylcyclohexene moiety at the A-ring, such as 1 and 7, give a regio- and stereoselective ene reaction when heated at low temperatures with dimethyl acetylenedicarboxylate. The structure and stereochemistry of the compound formed in the case of 1, e.g. 5, is determined by X-ray analysis.
Diels-alder reactions of methyl- and π-acceptor-substituted 2-vinylindoles with dimethyl acetylenedicarboxylate and tetracyanoethylene: Novel functio…
1991
The Diels-Alder reactions of the 2-vinylindoles 1a-1d, which are now readily accessible, with dimethyl acetylenedicarboxylate and tetracyanoethylene give rise to the novel 1,2-dihydro- and 1,2,3,4-tetrahydrocarbazoles 2, 4, and 5 as well as the fully aromatized carbazoles 3. With regard to the product spectrum, the mechanistic rationale comprises a Diels-Alder step, formal 1,3-hydrogen shift, ene reaction, and dehydrogenation. Conformational aspects of the 1,2-dihydrocarbazoles 2b and 2c are also discussed.
Theoretical Study of the Reaction of Dimethyl Acetylenedicarboxylate with 1-Methyl-2-(1-substituted vinyl)pyrroles
1995
Abstract A theoretical study of the transition structure for the electrophilic attack step of the 1-methyl-2-vinylpyrrole to dimethyl acetylenedicarboxylate is reported with analytical gradients at AM1 and PM3 semi-empirical levels and ab initio at 3-21G level. The geometry, electronic structure, and vector components are qualitatively computer level and model independent The competition of the Michael addition reactions and Diels-Alder reactions of 1-methyl-2-(1-substituted vinyl)pyrroles with dimethyl acetylenedicarboxylate has been studied at the PM3 semi-empirical level.
Synthesis and Chemical Reactivity of 5-Methoxy-2-vinyl-4-azaindoles
1997
Abstract 2-Vinyl-4-azaindoles are less reactive with dienophiles than 2-vinylindoles. 5-Methoxy-2-vinyl-4-azaindole 2a and its 1-methyl derivative 2a reacts with N-phenylmaleimide to yield cycloadducts only under vigorous conditions. 2b produces a cycloadduct with dimethyl acetylenedicarboxylate, while 2a yields a Michael-type adduct. Reactions with more reactive dienophiles gave only polymeric products.
The reactivity of 2-vinylindoles with dimethyl acetylenedicarboxylate
1984
Abstract 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 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 Co…
Aminobisphenolate supported tungsten disulphido and dithiolene complexes
2015
Dioxotungsten(vi) complexes with tetradentate amino bisphenolates were converted into the corresponding Cs-symmetric amino bisphenolate disulphido complexes by a reaction with either Lawesson's reagent or P2S5. Further reaction with diethyl acetylenedicarboxylate leads to the formation of diamagnetic tungsten(iv) dithiolene compounds. The syntheses, crystal structures, spectroscopic and electrochemical characterization of such disulphido and dithiolene complexes are presented.
ChemInform Abstract: Cycloaddition Reactions with Vinyl Heterocycles
2010
Publisher Summary The Diels-Alder reaction is one of the most common and elegant methods for the construction of six-membered rings. Although the number of Diels-Alder cycloadditions with open-chain and alicyclic dienes is very large, the number of examples with aromatic heterocyclic compounds is relatively small. The introduction of a vinyl group as a substituent onto a heterocycle increases the number of possible reactions. This new possibility, however attractive for synthetic purposes, is successful only with π-excessive five-membered heterocyclic derivatives with a few exceptions. The chapter discusses the reactions of vinyl heterocycles with carbodienophiles. The endocyclic and exo-en…