KOAc-promoted alkynylation of α-C–H bonds of ethers with alkynyl bromides under transition-metal-free conditions
作者:Jiajun Zhang、Pinhua Li、Lei Wang
DOI:10.1039/c4ob00002a
日期:——
KOAc-promoted α-position C–H activation and alkynylation of ethers with alkynyl bromides to 2-alkynyl ethers was developed under transition-metal-free conditions.
A metal-free direct alkylation of CâH bonds adjacent to an oxygen or nitrogen atom was developed. This reaction occurred between saturated heterocycles and ethynylbenziodoxolones under mild conditions. A series of 2-alkynyl cyclic alkanes that contain oxygen or nitrogen atoms were prepared in moderate to good yields.
Visible‐Light‐Induced Alkynylation of α‐C–H Bonds of Ethers with Alkynyl Bromides without External Photocatalyst
作者:Xiaofei Xie、Jie Liu、Lei Wang、Min Wang
DOI:10.1002/ejoc.201900872
日期:2020.3.15
An unprecedented direct alkynylation reaction of α‐C(sp3)–H bonds of ethers under visiblelight irradiation at room temperature withoutexternalphotocatalyst was developed.
Practical and Highly Selective CH Functionalization of Structurally Diverse Ethers
作者:Miao Wan、Zhilin Meng、Hongxiang Lou、Lei Liu
DOI:10.1002/anie.201407083
日期:2014.12.8
A trityl ion mediated CHfunctionalization of ethers with a wide range of nucleophiles at ambient temperature has been developed. The reaction displays high chemoselectivity and good functional group tolerance. The protocol also exhibits excellent regio‐ and diastereoselectivities for the unsymmetric ethers, thus stereoselectively generating highlyfunctionalized disubstituted 2,5‐trans tetrahydrofurans
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
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.