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An Olefinic 1,2‐Boryl‐Migration Enabled by Radical Addition: Construction of gem ‐Bis(boryl)alkanes
Author(s) -
Zhao Binlin,
Li Zexian,
Wu Yixiao,
Wang Yandong,
Qian Jiasheng,
Yuan Yu,
Shi Zhuangzhi
Publication year - 2019
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201903721
Subject(s) - chemistry , alkyl , radical , reagent , adduct , halide , boron , radical ion , photochemistry , cationic polymerization , medicinal chemistry , yield (engineering) , polymer chemistry , organic chemistry , ion , materials science , metallurgy
A series of in situ formed alkenyl diboronate complexes from alkenyl Grignard reagents (commercially available or prepared from alkenyl bromides and Mg) with B 2 Pin 2 (bis(pinacolato)diboron) react with diverse alkyl halides by a Ru photocatalyst to give various gem‐bis(boryl)alkanes. Alkyl radicals add efficiently to the alkenyl diboronate complexes, and the adduct radical anions undergo radical‐polar crossover, specifically, a 1,2‐boryl‐anion shift from boron to the α‐carbon sp 2 center. This transformation shows good functional‐group compatibility and can serve as a powerful synthetic tool for late‐stage functionalization in complex compounds. Measurements of the quantum yield reveal that a radical‐chain mechanism is operative in which the alkenyl diboronates acts as reductive quencher for the excited state of the photocatalyst.