Huan-Huan Zhao, Xu-Gang Zhang, Hao-Wen Jiang, Yong-Chun Luo,* and Peng-Fei Xu*
https://doi.org/10.1021/acs.orglett.5c00888
Herein, we report an Fe/Co dual-catalyzed strategy for synthesizing alkenyl unnatural amino acids and peptide modifications. This approach utilizes aspartic acid and glutamic acid derivatives as alkyl radical precursors. It avoids the use of expensive photoredox catalysts and substrate preactivation while preserving the chirality of the amino acids. Furthermore, this strategy enables both modification of peptides and the synthesis of amino-acid-based drug candidates for boron-neutron capture therapy (BNCT).
Hao-Ni Qin, Hao-Wen Jiang, Yi Zhao, Saira Qurban, Ke-Chun Wang and Peng-Fei Xu *
https://doi.org/10.1039/D4SC08085H
Substantial advancements have been achieved in the field of photocatalytic borylation utilizing 4c-7e Lewis base-boryl radicals. However, the utilization of 3c-5e neutral boryl radicals for C–B bond formation remains relatively underexplored due to their inherent instability. In this study, we successfully demonstrated the direct construction of C–B bonds using sodium tetraarylborate as a key reagent. This was accomplished by effectively stabilizing diaryl boryl radicals with nitrile compounds, thereby facilitating the synthesis of valuable boron-containing compounds. Overall, our research elucidates the significant role played by sodium tetraarylborate in enabling an efficient and versatile approach for synthesizing of 1,4,2- diazaborole analogs through a photocatalyzed [3 + 2]-annulation reaction. This mild and adaptable methodology expands synthetic strategies for obtaining diverse derivatives of 1,4,2-diazaboroles, with the RCN–BAr2 complex serving as an effective boron–nitrogen synthon that opens up pathways to multiple boron–nitrogen heterocycles. Furthermore, this breakthrough significantly enhances the applicability of sodium tetraarylborate in photoredox catalysis.
Dong-Sheng Ji,* Xin Zhang, Peiqin Zhang, Xiazhen Bao, Yong Yuan, Congde Huo,* and Peng-Fei Xu*
https://doi.org/10.1021/acs.orglett.4c04715
Herein, we present a visible-light-induced protocol for the synthesis of highly functionalized oxo-bridged oxocine skeletons. This method generates carbenes via visible-light-induced ortho-acyl diazo compounds, which are rapidly intercepted by the oxygen atom of an intermolecular acyl group to form a cyclic 1,3- dipole. The in situ generated highly reactive 1,3-dipole undergoes a facile formal [4 + 3] cycloaddition with alkenyl pyrazolinone, yielding [4.2.1]-oxo-bridged oxocine compounds.
