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22 articles match your search "retro Diels-Alder reaction"Results 1 to 10, sorted by relevance:
data reports
Open access
The crystal structure of the title pentacyclo-substituted naphthoquinone, C13H10O2 is described.
abstracts
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.
research communications
Open access
The tetrazine derivative, as well as the water molecule, of C12H9N7·H2O are involved in a hydrogen-bond network accompanied by π-stacking.
research communications
Open access
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—HO hydrogen bonds in the solid state, while the imide also features C—HO hydrogen bonds as well as C—Hπ and lone pair–π interactions.
data reports
Open access
Crystal structure of 1,3-diallyl-1,3,3a,4,7,7a-hexahydro-4,7-methano-2-benzothiophene 2,2-dioxide
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.
research communications
Open access
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—HO hydrogen bonds link the molecules to form inversion dimers, enclosing two (6) ring motifs.
organic compounds
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—HO hydrogen bonding is observed between the hydroxyl groups.
organic compounds
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.
organic compounds
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—HO 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—HO and C—Hπ(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—HO hydrogen-bonded dimers stabilized by aromatic π–π interactions. Dimers of (IIa) are connected into a chain by weak C—Hπ(arene) interactions.
organic compounds
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.