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Photoredox‐Catalyzed Cyclopropanation of 1,1‐Disubstituted Alkenes via Radical‐Polar Crossover Process
Author(s) -
Luo Wenping,
Yang Yi,
Fang Yewen,
Zhang Xinxin,
Jin Xiaoping,
Zhao Guicai,
Zhang Li,
Li Yan,
Zhou Wanli,
Xia Tingting,
Chen Bin
Publication year - 2019
Publication title -
advanced synthesis and catalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.541
H-Index - 155
eISSN - 1615-4169
pISSN - 1615-4150
DOI - 10.1002/adsc.201900708
Subject(s) - chemistry , cyclopropanation , allylic rearrangement , bromide , halide , radical cyclization , alkyl , photoredox catalysis , radical , photochemistry , catalysis , cascade , medicinal chemistry , combinatorial chemistry , photocatalysis , organic chemistry , chromatography
The photoredox‐neutral catalyzed cyclopropanation of 1,1‐disubstituted alkenes via radical addition‐anionic cyclization cascade has been successfully developed. Another new protocol based on photocatalytic allylation and cyclopropanation cascade was also described between allylic halide and halomethyl radical. In addition to the successful use of bis‐catecholato silicates as the alkyl radical precursors, the acyl and alkyl radicals derived from 1,4‐dihydropyridines were also engaged in this radical‐polar crossover process. The competing experiments displayed that the 3‐ exo ‐ tet mode of cyclization preferred over 4‐ exo and 5‐ exo cyclization modes, allowing for the selective 3‐ exo ‐ tet cyclization. The superior nucleofuge character of bromide over chloride and tosylate has been demonstrated in the reaction of bromomethyl radical with homoallylic (pseudo)halides. This new protocol is characterized by its redox‐neutral process, broad substrate scope, mild conditions, and good functional‐group compatibility.