Visible Light-Induced Direct S<sub>0</sub> → T<sub><i>n</i></sub> Transition of Benzophenone Promotes C(sp<sup>3</sup>)–H Alkynylation of Ethers and Amides
                                
                                    
                                        作者:Koki Matsumoto、Masaya Nakajima、Tetsuhiro Nemoto                                    
                                    
                                        DOI:10.1021/acs.joc.0c01573
                                    
                                    
                                        日期:2020.9.18
                                    
                                    Benzophenone has an S-0 -> S-1 absorption band at 365 nm. However, the rarely reported S-0 -> T-n transition occurs upon irradiation at longer wavelengths. Herein, we employed benzophenone as a catalyst and exploited its S-0 -> T-n transition in C(sp(3))-H alkynylations with hypervalent iodine reagents. The selective benzophenone excitation prevented alkynylating reagent decomposition, enabling the reaction to proceed under mild conditions. The reaction mechanism was investigated by spectroscopic and computational studies.