- Bromomethyl Silicate: A Robust Methylene Transfer Reagent for Radical-Polar Crossover Cyclopropanation of Alkenes
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A general protocol for visible-light-induced cyclopropanation of alkenes was developed with bromomethyl silicate as a methylene transfer reagent, offering a robust tool for accessing highly valuable cyclopropanes. In addition to α-aryl or methyl-substituted Michael acceptors and styrene derivatives, the unactivated 1,1-dialkyl ethylenes were also shown to be viable substrates. Apart from realizing the cyclopropanation of terminal alkenes, the methyl transfer reaction has been further demonstrated to be amenable to the internal olefins. The photocatalytic cyclopropanation of 1,3-bis(1-arylethenyl)benzenes was also achieved, giving polycyclopropane derivatives in excellent yields. With late-stage cyclopropanation as the key strategy, the synthetic utility of this transformation was also demonstrated by the total synthesis of LG100268.
- Luo, Wenping,Fang, Yewen,Zhang, Li,Xu, Tianhang,Liu, Yongjun,Li, Yan,Jin, Xiaoping,Bao, Jiakan,Wu, Xiaodong,Zhang, Zongyong
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p. 1778 - 1781
(2020/03/11)
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- Palladium-Catalyzed Divergent Arylation with Triazolopyridines: One-Pot Synthesis of 6-Aryl-2-α-styrylpyridines
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We have developed a new strategy for palladium-catalyzed arylation reactions with triazolopyridines, wherein two different chemical transformations (C-3 vs. C-7) are observed by differentiating the substrates using different bases. The reactive palladium carbenoids were directly generated from triazolopyridines and underwent denitrogenative arylations with aryl bromides. Intriguingly, when potassium carbonate was replaced with potassium tert-butoxide, direct C-H arylation occurred at the most acidic position (C-7). Moreover, two different catalytic arylation events were successfully performed in a one-pot sequence, providing a convenient access to 6-aryl-2-α-styrylpyridines.
- Moon, Youngtaek,Kwon, Soonhyung,Kang, Dahye,Im, Honggu,Hong, Sungwoo
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p. 958 - 964
(2016/04/05)
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- A masked diboron in Cu-catalysed borylation reaction: Highly regioselective formal hydroboration of alkynes for synthesis of branched alkenylborons
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The use of a masked diboron as a boron source in the presence of a Cu-N-heterocyclic carbene (NHC) catalyst enables alkyl-, aryl-, heteroatom- and silyl-substituted terminal alkynes to undergo α-selective formal hydroboration to give diverse branched alkenylboron compounds exclusively. Synthetic potential of this α-selective hydroboration has been demonstrated by total synthesis of pharmaceutically significant bexarotene and LG100268. This journal is the Partner Organisations 2014.
- Yoshida, Hiroto,Takemoto, Yuki,Takaki, Ken
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supporting information
p. 8299 - 8302
(2014/07/22)
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