- Practical and Modular Construction of C(sp3)-Rich Alkyl Boron Compounds
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Alkyl boronic acids and esters play an important role in the synthesis of C(sp3)-rich medicines, agrochemicals, and material chemistry. This work describes a new type of transition-metal-free mediated transformation to enable the construction of C(sp3)-rich and sterically hindered alkyl boron reagents in a practical and modular manner. The broad generality and functional group tolerance of this method is extensively examined through a variety of substrates, including synthesis and late-stage functionalization of scaffolds relevant to medicinal chemistry. The strategic significance of this approach, with alkyl boronic acids as linchpins, is demonstrated through various downstream functionalizations of the alkyl boron compounds. This two-step concurrent cross-coupling approach, resembling formal and flexible alkyl-alkyl couplings, provides a general entry to synthetically challenging high Fsp3-containing drug-like scaffolds.
- Yang, Yangyang,Tsien, Jet,Ben David, Ayala,Hughes, Jonathan M. E.,Merchant, Rohan R.,Qin, Tian
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p. 471 - 480
(2021/01/13)
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- Copper-Catalyzed Monoorganylation of Trialkyl Borates with Functionalized Organozinc Pivalates
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Organozinc pivalates, a recently developed air- and moisture-stable organozinc species, were found for the first time as excellent organometallic species in the monoorganylation of trialkyl borates whereby boronic acids were prepared in high yields. The significant advantage of organozinc pivalates over another previously employed organometallic reagents, e. g., organolithium reagents, Grignard reagents and organozinc halides, is that the generation of multiorganylation byproducts such as borinic acids and trialkylboranes were completely suppressed. Additionally, the in situ generated boronates could be directly arranged into Suzuki-Miyaura type cross-coupling reactions to produce biaryls in high yields.
- Fu, Ying,Gou, Bei-Lei,Shi, Chun-Zhao,Du, Zhengyin,Shen, Tong
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p. 4253 - 4257
(2018/09/18)
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- Cyclic Iodine Reagents Enable Allylic Alcohols for Alkyl Boronate Addition/Rearrangement by Photoredox Catalysis
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All-carbon quaternary centers are prevalent in bioactive small molecules. However, their efficient construction remains a formidable synthetic challenge. Here we report cyclic iodine(III) reagents enable the synthesis of cyclopentanones, cyclohexanones, and dihydrofuranones bearing α-quaternary centers by photoredox catalysis. The reaction proceeds by the formation of the novel cyclic iodine(III) reagent-allylic alcohol complex, which enables the first alkyl boronate addition and semi-pinacol rearrangement of allylic alcohols with dual alcohol and olefin activation. The reaction is suitable for gram scale synthesis and is transformable to alcohols, olefins, oximes, and lactones with an α-quaternary center in one step.
- Liu, Mingshang,Huang, Hanchu,Chen, Yiyun
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supporting information
p. 1209 - 1212
(2018/11/06)
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- Visible-Light-Induced C2 Alkylation of Pyridine N-Oxides
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A photoredox catalytic method has been developed for the direct C2 alkylation of pyridine N-oxides. This reaction is compatible with a range of synthetically relevant functional groups for providing efficient synthesis of a variety of C2-alkylated pyridine N-oxides under mild conditions. Mechanistic studies are consistent with the generation of a radical intermediate along the reaction pathway.
- Zhang, Wen-Man,Dai, Jian-Jun,Xu, Jun,Xu, Hua-Jian
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p. 2059 - 2066
(2017/02/26)
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- Dichloroborane-dioxane: An exceptional reagent for the preparation of alkenyl- and alkylboronic acids
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Terminal alkynes and alkenes were conveniently hydroborated to the corresponding alkenyl- and alkyldichloroboranes using dichloroborane-dioxane in dichloromethane. These dichloroboranes were hydrolyzed by water to the corresponding alkenyl- and alkylboron
- Josyula, Kanth V. B.,Gao, Peng,Hewitt, Chris
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p. 7789 - 7792
(2007/10/03)
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- Organoboranes. 30. Convenient procedures for the synthesis of alkyl- and alkenylboronic acids and esters
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Alkyl- and alkenyldibromoborane-dimethyl sulfide complexes, readily obtained by the hydroboration of alkenes and alkynes with dibromoborane-dimethyl sulfide (HBBr2-SMe2), react with water, giving the corresponding boronic acids, and with alcohols and glycols to give the corresponding esters. Various procedures have been developed for the preparation of boronic esters with primary and secondary alcohols, glycols, and tertiary alcohols. Boronic acids react with primary and secondary alcohols reversibly to form the corresponding esters. The equilibrium may be conveniently displaced in favor of ester by carrying out the reaction in pentane, from which the water component separates. This procedure does away with the necessity of azeotrope distillation of a ternary mixture, extensively used previously for the esterification of boronic acids.
- Brown, Herbert C.,Bhat,Somayaji, Vishwanatha
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p. 1311 - 1316
(2008/10/08)
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