Jiajing Tan

We have developed an electrophotochemical strategy that enables the facile synthesis of cross-benzoins via the decarboxylative cross-coupling of α-keto acids with aldehydes.

Sigmatropic rearrangements play a pivotal role in organic synthesis, providing a robust method for bond reorganization and the construction of complex molecular architectures with high precision and efficiency. An electrophilic aryne activation-based approach has enabled the development of a unique N -to- N [2,3]-sigmatropic rearrangement of allylhydrazines. This transition-metal free method demonstrated good selectivity control, and en route to versatile rearrangement products. Key advances also included the identification/isolation of the crucial aminimide intermediates, which empowered the further development of propargyl/benzyl rearrangement. Moreover, the synthetic value was demonstrated through scale-up experimentation, downstream derivatization, and DFT calculations that shed light on the mechanistic underpinnings.

The Sc(OTf)₃-catalyzed (3 + 3) annulation of quinoxaline-2(1H)-thiones and donor-acceptor cyclopropanes was achieved in the presence of DBU under air to give functionalized 2,3-dihydro-4H-thiopyrano[2,3-b]quinoxaline derivatives in moderate to high yields. The annulation includes tandem nucleophilic ring opening, nucleophilic addition, and radical oxidative aromatization. It provides not only a new (3 + 3) annulation strategy but also a new synthetic method for fused tricyclic quinoxaline derivatives.

This work presents a photoinduced radical addition of 4-alkyl-1,4-DHPs to vinyl azides for ketone synthesis. Single- and dual-parameter Hammett analysis clarifies the silver-mediated activation of vinyl azides for low-reactivity radicals.

A facile catalyst-free regioselective 1,6-aza-Michael addition of para-quinone methides with tetrazoles was efficiently developed using water as a green solvent. This process exhibited broad substrate compatibility, including benzotriazole, pyrazole, and indazole, yielding the corresponding N-substituted azoles with excellent efficiency and regioselectivity. To demonstrate the practicality of this methodology, gram-scale reactions were successfully conducted. The possible mechanistic pathway is elucidated based on the preliminary results from control experiments as well as discrete fourier transform (DFT) calculations, which reveal that the solvent water plays a crucial role in facilitating the reaction by forming hydrogen bonds with the substrate, thereby enhancing the reaction progress.

This work presents a novel, eco-friendly, transition metal-free method for synthesizing β-enaminones via visible-light-induced photo-acylation of vinyl azides. The reaction mechanism has been thoroughly investigated using Hammett analysis.

Organoboron fluorophores have emerged as promising functional dyes with versatile photophysical properties. The innovative strategy of incorporating multiple boron coordination units has significantly broadened their application potential. Herein, a new array of quinoxaline-based organoboron fluorophores was designed and developed. The bis-boron coordination anchored core displays remarkable stability, and enables diversity-oriented post-complexation functionalization (PCF) through various transition metal catalyzed couplings, thereby facilitating the subsequent structure–activity relationship (SAR) study. The obtained innovative dyes exhibit wavelength-tunable fluorescence ranging from 490 nm to 600 nm, with large Stokes shifts and quantum yields up to 91% in toluene. Furthermore, the practical applications of the methylthio-substituted bis(BF₂) complexes as the highly efficient hypochlorite detection probes are demonstrated.

We reported a sunlight-promoted, three-component reaction involving glyoxal hydrates, anilines, and 4-alkyl DHPs for the synthesis of α-aminoketones with high yields under ambient conditions without additional photocatalysts or additives.

A visible-light-induced photocatalyst-free acylative pyridylation of styrenes with 4-acyl-1,4-dihydropyridines (DHPs) and 4-cyanopyridines has been described, featuring mild reaction conditions, a broad substrate scope, and good functional group tolerance. The reaction could also be performed under sunlight irradiation albeit with a slightly lower conversion. 4-Acyl-1,4-DHPs serve a dual role, acting as both a photoreductant to reduce the cyanopyridine to its radical anion intermediate and a radical precursor to produce the acyl radical. The mechanism was especially elucidated through the Hammett analysis, with the quadratic linear regression analysis by using radical dual parameters, σ_mb and σ_jj·. The findings from Hammett analysis further demonstrate that the rate-limiting step of the process is the single electron transfer between 4-acyl-1,4-DHPs and 4-cyanopyridines.