位阻效应
化学
反应性(心理学)
光化学
非对映体
准分子
电子效应
超快激光光谱学
立体选择性
反应机理
选择性
组合化学
计算化学
光谱学
立体化学
催化作用
有机化学
荧光
病理
替代医学
医学
物理
量子力学
作者
Javier Mateos,Francesco Rigodanza,Paolo Costa,Mirco Natali,Alberto Vega‐Peñaloza,Elisa Fresch,Elisabetta Collini,Marcella Bonchio,Andrea Sartorel,Luca Dell’Amico
标识
DOI:10.1038/s44160-022-00191-5
摘要
Information gained from in-depth mechanistic investigations can be used to control the selectivity of reactions, leading to the expansion of the generality of synthetic processes and the discovery of new reactivity. Here, we investigate the mechanism of light-driven [2+2] heterocycloadditions (Paternò-Büchi reactions) between indoles and ketones to develop insight into these processes. Using ground-state UV-Vis absorption and transient absorption spectroscopy (TAS), together with DFT calculations, we found that the reactions can proceed via an exciplex or electron-donor-acceptor (EDA) complex, which are key intermediates in determining the stereoselectivity of the reactions. We used this discovery to control the diastereoselectivity of the reactions, gaining access to previously inaccessible diastereoisomeric variants. When moving from 370 to 456 nm irradiation, the EDA complex is increasingly favoured, and the diastereomeric ratio (d.r.) of the product moves from >99:<1 to 47:53. In contrast, switching from methyl to ipropyl substitution favours the exciplex intermediate, reversing the d.r. from 89:11 to 16:84. Our study shows how light and steric parameters can be rationally used to control the diastereoselectivity of photoreactions, creating mechanistic pathways to previously inaccessible stereochemical variants.
科研通智能强力驱动
Strongly Powered by AbleSci AI