The enzyme SpnF, involved in the biosynthesis of spinosyn A, catalyzes a formal [4+2] cycloaddition of a 22-membered macrolactone, which may proceed as a concerted [4+2] Diels-Alder reaction or a stepwise [6+4] cycloaddition followed by a Cope rearrangement. Quantum mechanics/molecular mechanics (QM/MM) calculations combined with free energy simulations show that the Diels-Alder pathway is favo...

Functionalization of endohedral metallofullerenes (EMFs) is an active line of research that is important for obtaining nanomaterials with unique properties that might be used in a variety of fields, ranging from molecular electronics to biomedical applications. Such functionalization is commonly achieved by means of cycloaddition reactions. The scarcity of both experimental and theoretical stud...

2+2] and [4+2] cycloaddition reactions of 1,3-cyclohexadiene on the Si(001) surface were studied. It is shown that not only the [4+2] cycloaddition reaction but also the [2+2] cycloadditions can occur on the Si(001) surface. Surface isomerization reactions connecting [4+2] and [2+2] are very unlikely due to a high energy barrier, implying that the surface reactions are kinetically controlled. T...

The first Diels-Alder cycloaddition of o-quinodimethane to SWNT has been performed under microwave irradiation.

The bioorthogonal chemical reporter strategy is emerging as a versatile method for the labeling of biomolecules, such as nucleic acids, lipids, carbohydrates, and proteins. In this approach, an abiotic chemical functionality (reporter) is incorporated into a target biomolecule and can then react with a complementary bioorthogonal functional group linked to one of a diverse set of probes. The az...

In this work, three possible mechanisms, including mechanisms A and B associated with the stereoselective [2 + 2] cycloaddition product and mechanism C associated with the [2 + 2 + 2] cycloaddition product, have been investigated for N-heterocyclic carbenes (NHCs) catalyzed cycloadditions of ketenes with isothiocyanates by using density functional theory (DFT). Our calculated results suggest th...

Natural products and their signature fragments are an enduring resource for identifying biological modulators. A number of biologically active alkaloids, such as strychnofoline and isorhynchophylline (Fig. 1), feature spiroindolizidine oxindoles. This fragment is considered ‘privileged’ for potential therapeutic investigation and there is much interest in developing expedient synthesis of such ...

the catalytic highly regio-, diastereo-, and enantioselective synthesis of a small library of spiropyrrolizidineoxindolesvia a four-component 1,3-dipolar cycloaddition reaction of azomethine ylides, derived from isatin, with electron-deficient dipolarophilewas described. the process occurs at room temperature in aqueous ethanol as a green solvent and in the presence of a bidendatebis(imine)–cu(...

Nitrile Oxide−Dehydroalanine Cycloaddition is a bioconjugation strategy between dehydroalanine-containing proteins and nitrile oxides, remarkably, in fully aqueous-buffered systems without an additional catalyst. This novel method of chemical protein modification forms isoxazoline ring enhancing the diversity function structure. The 1,3-dipolar cycloaddition reaction adds fluorescent label to f...

Key words (±)-talatisamine - Diels–Alder reaction [2+2] photo-cycloaddition Lemieux–Johnson oxidation retro-aldol–aldol Wagner–Meerwein rearrangement aza-Prins