Hui Zhang, Ke-Chun Wang, Wei-Jun Cao, Ying-Jie Wang, Peng-Fei Xu*
https://doi.org/10.1002/ejoc.70504
Abstract
Herein, we report a synthetic strategy that relies on a self-developed organic photocatalyst for the efficient construction of imidazolines and oxazolidines. Using readily available 4-methyl-N-(2-phenylallyl)benzenesulfonamide alkenes and redox-active esters (RAEs) or aryl diazonium tetrafluoroborates as substrates, the reaction proceeds in acetonitrile/acetone via photoredox-initiated radical addition followed by ionic cyclization, which involves the formation of a key nitrilium/imidate-type ionic intermediate. This transformation features mild reaction conditions and facile operation, not only expanding the application scope of the developed photocatalyst, but also providing a practical technical platform for the photocatalytic synthesis of structurally diverse bioactive molecules containing imidazoline and oxazolidine motifs.
Teng-Fei Xiao, Ming-Ming Li, Dong Xie, Yu-Cheng Gu, Pan-Pan Zhou*, Guo-Qiang Xu* & Peng-Fei Xu*
https://doi.org/10.1007/s11426-025-3052-7
Abstract
Bicyclo[1.1.1]pentanes (BCPs) have emerged as valuable saturated bioisosteres of arenes in drug discovery. While 1,3-disubstituted BCPs are increasingly accessible, the pharmaceutical value of 2-substituted BCPs as replacements for MIMIC ortho-/meta-substituted arene rings, modular access to these scaffolds remains elusive. Here we report a visible-light-mediated σ-bond insertion strategy that exploits triplet energy transfer catalysis to convert readily available bicyclo[1.1.0]butanes (BCBs) into 2-substituted BCPs. The reaction proceeds via triplet carbene intermediates that engage in regioselective insertion into the central C–C σ-bond of BCBs. Mechanistic studies, supported by radical trapping experiments, Stern-Volmer analysis, light-dependence assays, and density functional theory (DFT) calculations, reveal a radical mechanism. The key challenges in this transformation include: controlling the highly reactive radical intermediates; achieving regioselective addition to the highly strained BCB (strain energy: 53.8 kcal/mol), and reconstructing the highly strained BCP ring (strain energy: 54.4 kcal/mol) during radical coupling.
Hui Zhang, Ying-Jie Wang, Hao-Wen Jiang,* and Peng-Fei Xu*
https://doi.org/10.1021/acs.orglett.5c05168
ABSTRACT: Herein, we report a strategy for the methylalkylation of unactivated alkenes via synergistic photoredox/nickel catalysis. This mild transformation employs di-tert-butyl peroxide (DTBP) as a bifunctional reagent, which serves simultaneously as a hydrogen atom transfer (HAT) reagent and a source of methyl radical, thereby facilitating the coupling of malonate-derived radicals with alkenes. By integrating HAT with radical selectivity control, the method enables the formation of two C(sp 3 ) bonds in a single synthetic operation, offering a streamlined route to valuable three-dimensional scaffolds.
Ai-Lian Wang, Yi-Fan Yao, Xu-Gang Zhang,* and Peng-Fei Xu*
https://doi.org/10.1021/acs.orglett.5c04773
ABSTRACT:
Herein, we report a catalyst-free, photosensitized strategy for synthesizing 1,2-amino alcohols. This transformation proceeds via the addition of an α-hydroxymethyl radical to an in situ-generated alkyliminium ion. The α-hydroxymethyl radical is formed by the radical Brook rearrangement of a (trimethylsilyl)- methoxy radical generated from an electron donor-acceptor (EDA) complex between Hantzsch ester and N-((trimethylsilyl)- methoxy)phthalimide. Therefore, this Mannich-type reaction establishes an additive-free, modular, and simple approach for the synthesis of 1,2-amino alcohols.
Teng-Fei Xiao, Ke-Rui Jian, Yu-Cheng Gu, Guo-Qiang Xu and Peng-Fei Xu
https://doi.org/10.1039/D5SC06987D
ABSTRACT
Existing strategies are typically limited to modifying a C–H site (a or b-position) of saturated cyclic amines, but the asymmetric difunctionalization of vicinal C–H bonds remains a formidable challenge. To address this challenge, this work introduces a synergistic catalytic system that merges visible-light photocatalysis with asymmetric copper and chiral phosphoric acid catalysis. This system enables the enantioselective synthesis of ring-fused amine skeletons by activating vicinal C–H bonds in straightforward saturated cyclic amines. The reaction proceeds in good yields (up to 76%) and excellent enantioselectivity (up to 92% ee). This work describes detailed mechanistic studies that identify the specific dual chiral catalytic system that forms the basis for the enantioselectivity.
