Photoswitchable Oxidopyrylium Ylide for Photoclick Reaction with High Spatiotemporal Precision: A Dynamic Switching Strategy to Compensate for Molecular Diffusion

• Published in: Angewandte Chemie 2023-04, Vol.135 (17), p.n/a
• Main Authors: Xie, Xinyu, Hu, Fuqiang, Zhou, Yuqiao, Liu, Zhihao, Shen, Xin, Fu, Jielin, Zhao, Xiaohu, Yu, Zhipeng
• Format: Article
• Language: English
• Subjects: Aqueous solutions; Bioorthogonal Ligation; Chemistry; Conjugation; Cycloaddition; Cycloadditions; Dipoles; Membranes; Molecular diffusion; Photoactivation; Photochromism; Photoclick Reactions; Reagents; Spatial discrimination; Spatial resolution; Stimulation
• ISSN: 0044-8249; 1521-3757
• DOI: 10.1002/ange.202300034

We describe a novel type of photoclick reaction between 2,3‐diaryl indenone epoxide (DIO) and ring‐strained dipolarophiles, in which DIO serves as a P‐type photoswitch to produce mesoionic oxidopyrylium ylide (PY) to initiate an ultra‐fast [5+2] cycloaddition (k2hν=1.9×105 M−1 s−1). The photoisomerization between DIO and PY can be tightly controlled by either 365 or 520 nm photo‐stimulation, which allows reversion or regeneration of the reactive PY dipole on demand. Thus, this reversible photoactivation was exploited to increase the chemoselectivity of the [5+2] cycloaddition in complex environments via temporal dual‐λ stimulation sequences and to recycle the DIO reagent for batch‐wise protein conjugation. A dynamic photoswitching strategy is also proposed to compensate for molecular diffusion of PY in aqueous solution, enhancing the spatial resolution of lithographic surface decoration and bioorthogonal labeling on living cells via a spatiotemporal dual‐λ photo‐modulation. The photoswitching equilibrium between 2,3‐diaryl indenone epoxide (DIO) and mesoionic oxidopyrylium ylide (PY) is governed by dual‐λ gating, in which PY can undergo fast [5+2] cycloaddition with BCN. A photoswitchable strategy for photoclick labeling with spatiotemporal control was developed, recycling the unreacted PY to minimize side‐effects. Also, molecular diffusion of the reactive PY was compensated for by improvement of the spatial accuracy.