| Autor: |
Xiaofei Xie, Yongmin Ma, Zhiming Wang, Tai-Ping Zhou, Rong-Zhen Liao, Hong Pan, Xiao Geng, Lei Wang, Pinhua Li, Jianguo Yang, Man-Yi Han |
| Rok vydání: |
2021 |
| Předmět: |
|
| DOI: |
10.21203/rs.3.rs-523200/v1 |
| Popis: |
A highly regioselective and diastereoselective [2+2] cross-photocycloaddition between the electron-poor and electron-rich/electron-neutral alkenes under visible-light irradiation was developed. In the absence of an external photocatalyst, the substrates 1 and 4 reacted with rigid cyclic alkoxyethenes to generate (cis,cis)-anti-head-to-head heterocoupled [2+2] products in high yields with regiospecificity and good diastereoselectivity. Meanwhile, the reactions of 1 and 4 with (Z)- and (E)-1,2-diphenylethenes yielded the desired products in good yields with a high ratio of d.r. It is important to note that no geometric isomerization of olefins was observed during the reaction. Mechanistic studies and DFT calculations suggested that 1 and 4 having ortho-ethynyl and cyano groups as a self-photocatalyst play a very important role in the reaction and a five-membered ring diradical intermediate (Int1) was formed via an intramolecular radical addition. The obtained regioselectivity and diastereoselectivity were confirmed by X-ray structural analysis of the representative products. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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