There is currently a tremendous interest in developing bioorthogonal "click chemistry" methods for the modification of biopolymers. Very recently, inverse-electron-demand Diels-Alder reactions have received attention, but to date they have not been applied to nucleic acids. Here we describe the first example of DNA modification by inverse-electron-demand Diels-Alder reaction. We synthesized fou...

Stimuli-responsive polymers, with properties changing upon different environmental factor variations such as pH, light, mechanical stress or temperature, and polymeric nanoparticles have found many important applications in fields drug delivery, biosensing research. In this work, thermoresponsive that are able to react by Diels-Alder reaction (a diene-dienophile cycloaddition) were studied. The...

Renewable production of p-xylene from [4 + 2] Diels− Alder cycloaddition of 2,5-dimethylfuran (DMF) and ethylene with H−Y zeolite catalyst in n-heptane solvent is investigated. Experimental studies varying the solid acid catalyst concentration reveal two kinetic regimes for the p-xylene production rate: (i) a linear regime at low acid site concentrations with activation energy Ea = 10.8 kcal/mo...

Common cases of cycloaddition include concerted (2 + 4) and stepwise (2 + 2) reactions which latter are usually easily recognizable as involving biradicals or dipolar ions. The addition in situ of dichioroketene to 2,4-hexadiene and 2butene is stereospecific, as required by the (2 + 2a) mechanism, but is followed by rapid base-catalysed rearrangement of the resulting 2,2-dichiorocyclobutanones ...

Strain-promoted inverse electron-demand Diels-Alder cycloaddition (SPIEDAC) reactions between 1,2,4,5-tetrazines and strained dienophiles, such as bicyclononynes, are among the fastest bioorthogonal reactions. However, the synthesis of 1,2,4,5-tetrazines is complex and can involve volatile reagents. 1,2,4-Triazines also undergo cycloaddition reactions with acyclic and unstrained dienophiles at ...

o-Quinodimethanes have remarkable utility as reactive intermediates in Diels–Alder reactions, enabling significantly accelerated routes to complex polycyclic compounds. The discovery of different discrete precursors thermally generate o-quinodimethanes thereby greatly augmented their availability and versatility. However, due the required high temperatures immense reactivity o-quinodimethanes, ...

The [4+2] cycloaddition of 3-alkoxyfurans with Nsubstituted maleimides provides the first general route for preparing endo-cantharimides. Unlike the corresponding reaction with 3H furans, the reaction can tolerate a broad range of 2-substitued furans including alkyl, aromatic, and heteroaromatic groups. The cycloaddition products were converted into a range of cantharimide products with promisi...

The intrinsic reactivity of eight gaseous, mass-selected 2-azabutadienyl cations toward polar [4(+) + 2] cycloaddition with ethyl vinyl ether has been investigated by pentaquadrupole mass spectrometric experiments. Cycloaddition occurs readily for all the ions and, with the only exception of those from the N-acyl 2-azabutadienyl cations (N-acyliminium ions), the cycloadducts are found to dissoc...

One hundred years after the birth of Kurt Alder and seventy-five years after the discovery of his famous reaction, one of the most important and fascinating transformations in chemistry, research on that process continues to surprise, excite, delight, and inform the chemical community. This article is based on presentations given first at the University of Cologne, Germany (Kurt Alder lecture, ...

The [4+2] cycloaddition of 3-alkoxyfurans with N-substituted maleimides provides the first general route for preparing endo-cantharimides. Unlike the corresponding reaction with 3H furans, the reaction can tolerate a broad range of 2-substitued furans including alkyl, aromatic, and heteroaromatic groups. The cycloaddition products were converted into a range of cantharimide products with promis...