Visible Light Promoted [3+2]-Cycloaddition for the Synthesis of Cyclopenta[b]chromenocarbonitrile Derivatives.

In the manuscript, a novel method for the preparation of cyclopenta[b]chromenocarbonitrile derivatives via [3+2] cycloaddition reaction of substituted 3-cyanochromones and N-cyclopropyloamines initiated by visible light catalysis has been described. The reaction was performed in the presence of Eosin Y as a photocatalyst. The key parameters responsible for the success of the described strategy are visible light, a small amount of photoredox catalyst, an anhydrous solvent, and an inert atmosphere.

Doubly vinylogous and doubly rearomative functionalization of 2-alkyl-3-furfurals.

The manuscript describes a straightforward functionalization of 2-alkyl-3-furfurals via simple aminocatalytic conjugate addition. The reaction proceeds through the formation of dearomatized dienamine-like intermediate that undergoes 1,6-addition to 4-alkylidene-2,6-dialkylcyclohexa-2,5-dienones. This process can be described as doubly rearomative as it proceeds with the re-formation of both furan and phenyl aromatic moieties. Target products have been obtained in a highly stereoselective manner, providing an interesting example of 2-alkyl-3-furfural functionalization via doubly vinylogous Michael addition. The mechanism of the reaction has been studied by means of computational methods.

On the origins of stereoselectivity in the aminocatalytic remote alkylation of 5-alkylfurfurals.

In the manuscript, computational studies on the remote alkylation of 5-alkylfurfurals proceeding via formation of the corresponding trienamine intermediate are presented. By the means of density functional theory (DFT) calculations and the symmetry-adapted perturbation theory (SAPT) method, interesting insights into the mechanism of the reaction have been provided explaining the influence and contribution of different molecular interactions on the observed reactivity as well as on the enantio- and diastereoselectivity of the process. The studies have been extended to the thiophene analogue of the starting furfural derivative and the results obtained verified experimentally.

Dearomative, aminocatalytic formal normal-electron-demand aza-Diels-Alder cycloaddition in the synthesis of tetrahydrofuropyridines.

In the manuscript the application of dearomative formal normal-electron-demand aza-Diels-Alder cycloaddition in the synthesis of tetrahydrofuropyridines is described. The developed approach utilizes aminocatalytic activation of 2-alkyl-3-furfurals that proceeds via formation of the dearomatized dienamine intermediate. Initially obtained cycloadducts have been subjected to subsequent transformations providing access to tetrahydrofuropyridines or functionalized cinnamates. The mechanism of the process has been confirmed by DFT calculations.

Dearomative Michael addition involving enals and 2-nitrobenzofurans realized under NHC-catalysis.

In this manuscript, the first enantioselective dearomative Michael addition between α,ß-unsaturated aldehydes and 2-nitrobenzofurans realized under N-heterocyclic carbene activation has been described. The reaction proceeds via addition of homoenolate to Michael acceptors leading to the formation of biologically important heterocycles with high yields and stereoselectivities. Their functionalization potential has been confirmed in selected, diastereoselective transformations.

Enantioselective H-bond-directed vinylogous iminium ion strategy for the functionalization of vinyl-substituted heteroaryl aldehydes.

In this work the first H-bond-directed vinylogous iminium ion strategy has been developed as a convenient strategy for the γ,δ-functionalization of vinyl-substituted heteroaromatic aldehydes. Their reaction with α-mercaptoketones proceeds in a cascade manner involving 1,6-addition followed by intramolecular aldol reaction. Excellent stereoselectivities have been obtained as a result of the H-bond interactions controlling the outcome of the cyclization step. The application of the strategy for the synthesis of tricyclic compounds bearing furan, tetrahydrothiophene and dihydropyran moieties has also been demonstrated.