- β-Bromoenol phosphate as a new precursor for the modular regioselective synthesis of substituted furans
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Owing to its importance in various realms of chemistry, furan occupies a position of eminence among heterocycles. Despite the availability of many methodologies for the synthesis of variably substituted furans, a modular convenient synthesis of 2,4-disubstituted furans remains challenging. The present work attempts to bridge that gap through a novel annulation-based approach using feedstock chemicals such as methyl ketones and their easily available derivatives, β-bromoenol phosphates. We have demonstrated a hitherto unknown reactivity of β-bromoenol phosphates which is responsible for the observed regioselectivity. The reaction requires only sodium hydride as the base under mild conditions. The scope of the reaction was found to be broad with the possibility of obtaining even tri-substituted furans besides a variety of 2,4-disubstituted furans. The methodology was applied to obtain synthetically challenging 3-acylfuran derivatives as well. The newly developed methodology is characterized by the modularity, regioselectivity as well as its practicality owing to easily available starting materials and fast reaction times.
- Fernandes, Rushil,Mhaske, Krishna,Narayan, Rishikesh
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- Suzuki-Miyaura cross-coupling reaction of 1,2-oxaborol-2(5H)-ols with carboxylic anhydrides: A new method to furans
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An efficient one-step method has been developed to construct furans via a Suzuki-Miyaura cross-coupling reaction of 1,2-oxaborol-2(5H)-ols with carboxylic anhydrides. In the presence of Pd(OAc)2/PCy3, the multi-substituted alkenylboron compounds could couple with anhydrides to obtain furans in moderate-to-good yields. The addition of bases promoted the coupling reaction, and the plausible reaction mechanism was proposed.
- Yu, Tao,Wu, Xin-Yan,Yang, Jun
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supporting information
p. 4071 - 4074
(2014/07/22)
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- Oxidative cross-coupling of allenyl ketones and organoboronic acids: Expeditious synthesis of highly substituted furans
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Allenyl ketones are employed as coupling partners in palladium-catalyzed oxidative cross-coupling reactions with organoboronic acids. This reaction constitutes an efficient methodology for the synthesis of highly substituted furan derivatives. Palladium-carbene migratory insertion is proposed as the key step in this transformation. Migration patterns: Allenyl ketones are employed as a coupling partner in a palladium-catalyzed oxidative cross-coupling reaction with organoboronic acids. This reaction constitutes an efficient methodology for the synthesis of highly substituted furan derivatives. Palladium-carbene migratory insertion is proposed as the key step in this transformation. BQ=1,4-benzoquinone.
- Xia, Ying,Xia, Yamu,Ge, Rui,Liu, Zhen,Xiao, Qing,Zhang, Yan,Wang, Jianbo
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supporting information
p. 3917 - 3921
(2014/05/06)
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- Synthesis of 2,4-disubstituted furans and 4,6-diaryl-substituted 2,3-benzo-1,3a,6a-triazapentalenes
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Reactions of acylacetylenes 1a-h with benzotriazole 2 give intermediates 3a-h. The treatment of 3a-h with trimethylsulfonium iodide in the presence of base give intermediate oxiranes 4a-h and 2,3-benzo-1,3a,6a-triazapentalenes 7d-g depending on substituent. Acid-catalyzed rearrangement of crude 4a-h give 2,4-disubstituted furans 5a-h.
- Katritzky, Alan R.,Hür, Deniz,Kirichenko, Kostyantyn,Ji, Yu,Steel, Peter J.
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p. 109 - 121
(2016/07/15)
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