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Efficient Synthesis of Benzofurans via Cross‐Coupling of Catechols with Hydroxycoumarins Using O 2 as an Oxidant Catalyzed by AlPO 4 ‐Supported Rh Nanoparticle
Author(s) -
Maeno Zen,
Yamamoto Masanobu,
Mitsudome Takato,
Mizugaki Tomoo,
Jitsukawa Koichiro
Publication year - 2019
Publication title -
chemistryselect
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.437
H-Index - 34
ISSN - 2365-6549
DOI - 10.1002/slct.201903117
Subject(s) - benzofuran , catalysis , chemistry , nanoparticle , nucleophile , combinatorial chemistry , coupling reaction , stereochemistry , organic chemistry , nanotechnology , materials science
An efficient synthesis of benzofuran derivatives via the cross‐coupling of catechols and hydroxycoumarins in H 2 O using O 2 as an ideal oxidant is reported. The above reaction allows the direct use of substrates without prefunctionalization, involves formation of C−C and C−O bonds in cascade manner, and affords H 2 O as the sole by‐product. This simple and clean reaction is achieved by the development of an AlPO 4 ‐supported Rh nanoparticle catalyst. The catalyst was applicable to the synthesis of a wide range of benzofurans. We also successfully utilized this catalytic method for total synthesis of flemichapparin C, one of the naturally occurring coumestans exhibiting bioactivity. The combined functions of Rh nanoparticles and AlPO 4 play a key role in this reaction where in situ generated o ‐benzoquinone by Rh nanoparticles is possibly an intermediate for nucleophilic addition to hydroxycoumarins on AlPO 4 .