Synlett 2017; 28(14): 1733-1737
DOI: 10.1055/s-0036-1588494
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© Georg Thieme Verlag Stuttgart · New York

Bromine-Radical-Mediated Synthesis of β-Functionalized β,γ- and δ,ε-Unsaturated Ketones via C–H Functionalization of Aldehydes

Takashi Kippo
a   Department of Chemistry, Graduate School of Science, Osaka Prefecture University, Sakai, Osaka 599-8531, Japan   eMail: ryu@c.s.osakafu-u.ac.jp
,
Yuki Kimura
a   Department of Chemistry, Graduate School of Science, Osaka Prefecture University, Sakai, Osaka 599-8531, Japan   eMail: ryu@c.s.osakafu-u.ac.jp
,
Mitsuhiro Ueda
a   Department of Chemistry, Graduate School of Science, Osaka Prefecture University, Sakai, Osaka 599-8531, Japan   eMail: ryu@c.s.osakafu-u.ac.jp
,
Takahide Fukuyama
a   Department of Chemistry, Graduate School of Science, Osaka Prefecture University, Sakai, Osaka 599-8531, Japan   eMail: ryu@c.s.osakafu-u.ac.jp
,
Ilhyong Ryu*
a   Department of Chemistry, Graduate School of Science, Osaka Prefecture University, Sakai, Osaka 599-8531, Japan   eMail: ryu@c.s.osakafu-u.ac.jp
b   Department of Applied Chemistry, National Chiao Tung University, Hsinchu 30010, Taiwan
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This work has been supported by a Grant-in-Aid for Scientific Research from the MEXT (no. 15H05850). T.K. acknowledges the Research Fellowship of the Japan Society for the Promotion of Science for Young Scientists.
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Publikationsverlauf

Received: 26. April 2017

Accepted after revision: 15. Juni 2017

Publikationsdatum:
29. Juni 2017 (online)


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Published as part of the ISHC Conference Special Section

Abstract

The bromine-radical-mediated allylation reaction of aldehydes was studied. In the presence of V-65 as radical initiator, the reaction of aldehydes with allyl bromides gave β,γ-unsaturated ketones in good yields (13 examples, 45–84%). The reaction is triggered by hydrogen abstraction from the aldehyde by bromine radical to form an acyl radical, which undergoes an SH2′-type addition–elimination reaction with allyl bromides to give coupling products with liberation of bromine radical. Three-component coupling reactions comprising aldehydes, electron-deficient alkenes, and methallyl bromide also proceeded to give δ,ε-unsaturated ketones.

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