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Search query: retro Diels-Alder reaction

22 articles match your search "retro Diels-Alder reaction"

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The crystal structure of the title penta­cyclo-substituted naphtho­quinone, C13H10O2 is described.

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Acta Cryst. (2014). A70, C923
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The early stages of molecular rearrangements are often apparent in the crystal structures of molecules susceptible to that rearrangement. For example, if a particular bond is broken, or if a particular group migrates during the rearrangement, then deviations of bond distances and angles from their `standard values' along the reaction coordinate are often observed. This is the structure correlation principle,1 which holds provided the molecule exists in the ground state, in a geometry, which is similar to the transition state geometry for the reaction. In this geometry the frontier orbitals whose interactions facilitate the reaction, can mix in the ground state. This paper discusses the application of this principle to pericyclic fragmentation reactions related to the retro Diels Alder reaction, using low temperature X-ray structural analysis of a range of model substrates. The substrates can be classified on the basis of this data into three groups: (i) those that undergo a synchronous retro Diels Alder reaction, (2) those that undergo an asynchronous retro Diels Alder reaction, and (3) those that react via a 2-step process. Examples of molecules falling into these three categories are given below.

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The tetra­zine derivative, as well as the water mol­ecule, of C12H9N7·H2O are involved in a hydrogen-bond network accompanied by π-stacking.

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The Diels–Alder cyclo­addition of cyclo­hepta­triene and maleic anhydride produces the title carb­oxy­lic anhydride; reaction of this anhydride with 4-bromo­phenyl­aniline forms the corresponding tetra­cyclic imide. The anhydride features C—H...O hydrogen bonds in the solid state, while the imide also features C—H...O hydrogen bonds as well as C—H...π and lone pair–π inter­actions.

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The title compound C15H20O2S, was identified as a product of di­allyl­ation of the meso-isomer of the corresponding norbornene sulfone, and it is an achiral compound. The five-membered heterocycle adopts an envelope conformation with the S atom deviating by 0.795 (3) Å from the other atoms of the ring (r.m.s. deviation = 0.0131). Both allyl groups are anti-oriented relative to the S atom but their double bonds are directed in opposite directions relative to the plane of the heterocycle.

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In the title di­epoxy­phenalene derivative, two di­hydro­furan and two tetra­hydro­furan rings, as well as one cyclo­hexane ring, are fused together with two methyl carboxyl­ate groups in positions 2- and 3-. In the crystal, two pairs of C—H...O hydrogen bonds link the mol­ecules to form inversion dimers, enclosing two R_{2}^{2}(6) ring motifs.

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The title compound, C17H22O4, is an oxabicyclo­[2.2.1]hept-5-ene with two exo-oriented hydroxy­methyl groups which are not parallel to each other. The mol­ecules are linked to each other by hydrogen bonds, resulting in a supra­molecular network. Inter­molecular O—H...O hydrogen bonding is observed between the hydroxyl groups.

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The title compound, C18H6Cl12O2, is a valuable precursor for the synthesis of mol­ecular tweezers. These tweezers require a tether part and two pincer units with syn orientation that can create a cavity large enough to include suitable guest compounds by noncovalent inter­action. The title compound is an ideal tether unit with syn-oriented double bonds, a π–π distance of 6.28 (1) Å, and the relative ease of functionalization of the two dichloro­ethene subunits.

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Methyl 2-benzamido-4-(3,4-dimeth­oxy­phenyl)-5-methyl­benz­o­ate, C24H23NO5, (Ia), and N-{5-benzoyl-2-[(Z)-2-meth­oxy­ethen­yl]-4-methyl­phenyl}benzamide, C24H21NO3, (IIa), were formed via a Diels–Alder reaction of appropriately substituted 2H-pyran-2-ones and methyl propiolate or (Z)-1-meth­oxy­but-1-en-3-yne, respectively. Each of these cyclo­additions might yield two different regioisomers, but just one was obtained in each case. In (Ia), an intra­molecular N—H...O hydrogen bond closes a six-membered ring. A chain is formed due to aromatic π–π inter­actions, and a three-dimensional framework structure is formed by a combination of C—H...O and C—H...π(arene) hydrogen bonds. Compound (IIa) was formed not only regioselectively but also chemoselectively, with just the triple bond reacting and the double bond remaining unchanged. Compound (IIa) crystallizes as N—H...O hydrogen-bonded dimers stabilized by aromatic π–π inter­actions. Dimers of (IIa) are connected into a chain by weak C—H...π(arene) inter­actions.

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In the structure of the title compound, C8H9ClOS, the six-membered ring has a boat conformation and the S-containing five-membered ring has an envelope conformation. The mol­ecules are linked only by weak van der Waals inter­actions.
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