Theoretical calculations of formation and reactivity of o-quinomethide derivatives of resorcin[4]arene with reference to empirical data

This paper describes theoretical reaction pathways of alkoxybenzyl derivatives of resorcin[4]arene leading to the formation of o-quinomethide derivatives of resorcin[4]arene (o-QMR[4]A). For each case, the activation energies for the formation of one o-QMR[4]A unit and the activation energies for the backward reaction were calculated. Based on the calculated reaction pathways, the reaction mechanism of o-QMR[4]A formation was proposed. Using the example of o-QMR[4]A generated from a methoxy derivative of resorcin[4]arene, the activation energies with selected nucleophiles were calculated and the reaction mechanisms discussed. Reaction path calculations were performed using the nudged elastic band method and semiempirical extended tight-binding method (GFN2-xTB). Using hydroxybenzyl derivatives of resorcin[4]arene as an example, a comparison of calculated activation energies by selected density-functional theory methods with GFN2-xTB and B97-3c geometries was performed. B97-3c and wB97XD methods were used to calculate the energies of the reactants (R), transition states (TS) and products (P) of the analysed reactions. Theoretical reaction mechanisms were discussed with respect to the orbital-weighted Fukui dual descriptor (Δfw ) and experimental data.

New insights into the reactivity of aminomethylene derivatives of resorc[4]arene: amine group transfer, conformational analysis, reaction mechanism

Using the example of aminomethylene derivatives of resorc[4]arene and their Michael reaction with 4-hydroxycoumarin, the possibility of transferring an amine molecule from substrate to product is demonstrated. The conformation of the aminocoumarin derivatives of resorc[4]arene formed is controlled by the polarity of the solvent. For one of the products, conformational analysis was performed by kinetic sampling using metadynamics (MTD). The energies of the final set of conformers were calculated by DFT (r2scan-3c). A reaction mechanism based on multiscale (ONIOM) Nudged Elastic Band (NEB-TS) reaction profile calculations is discussed.

Using the example of aminomethylene derivatives of resorc[4]arene and their Michael reaction with 4-hydroxycoumarin, the possibility of transferring an amine molecule from substrate to product is demonstrated.

Functionalized resorcin[4]arene-based coordination polymers as heterogeneous catalysts for click reactions

One Cu(i) and two Cd(ii) coordination polymers have been achieved using a 4-mercaptopyridine-functionalized resorcin[4]arene. 1 exhibits predominant efficiency and excellent recyclability for the synthesis of 1,2,3-triazoles and β-OH-1,2,3-triazoles.

Enaminone Substituted Resorcin[4]arene—Sealing of an Upper-Rim with a Directional System of Hydrogen-Bonds

The paper presents the synthesis of an enaminone resorcin[4]arene via a thermally activated o-quinomethide. The crystal structure indicates that in the solid state all enaminone units participate in a unidirectional seam of 12 intramolecular hydrogen bonds that are formed around the cavity. The molecule exhibits C₂ symmetry, with two opposite-laying enaminone units directed inside the cavity (“in”), and the other two units outside the cavity (“out”). In the solution the enaminone resorcin[4]arene exists as a mixture of conformers with distribution controlled by temperature and solvent. The experimental data are compared with the results of theoretical calculations using DFT B3LYP/6-31G(d,p) and fast semi-empirical DFTB/GFN2-xTB method in various solvents.

Synthesis of a coumarin derivative of resorcin[4]arene with solvent-controlled chirality

This paper presents the synthesis of a coumarin derivative of resorcin[4]arene (1) using a cascade thermolysis/Michael reaction. The influence of the hydrogen bonding system on the conformational rigidity and cyclochirality of the coumarin derivative of resorcin[4]arene was discussed; these properties depended on the proton-donor–acceptor properties of the solvent. Significant differences, which depended on the environment, in the coumarin derivative of resorcin[4]arene fluorescence were observed and discussed.

This paper presents the synthesis of a coumarin derivative of resorcin[4]arene (1) using a cascade thermolysis/Michael reaction.

Recent Advances in Organocatalyzed Asymmetric Synthesis of Benzopyran and Benzodihydropyran (Chromane) Nuclei

Benzopyran and benzodihydropyran (chromane) nuclei are the core structure of many natural products, in particular flavonoids. Many compounds possessing this structure are nutraceuticals, pharmaceutical nutrients. Therefore, benzopyran and chromane scaffolds are important building blocks in organic synthesis and many efforts have been made to set up efficient methods for their synthesis. In particular, asymmetric methods are of great importance, being natural products, and generally chiral substances. This review aims to cover literature in the range 2017–first half of 2019.