- Reductive Coupling of 2-Propyn-1-ones Promoted by Yb Metal or YbCl3-Zn
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Ytterbium metal promotes reductive coupling of 2-propyn-1-ones (1) to give cyclobutenes and 1,6-dioxo-2,4-hexadiene, whereas 1 is converted to 2,5-dihydrofurans on the treatment with YbCl3-Zn.
- Takaki, Ken,Nagase, Kyoko,Beppu, Fumikazu,Shindo, Takaaki,Fujiwara, Yuzo
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p. 1669 - 1672
(2007/10/02)
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- Exploratory Study on Photoinduced Single Electron Transfer Reactions of α,β-Epoxy Ketones with Amines
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Photoinduced single electron transfer (SET) reactions of α,β-epoxy ketones have been studied using alkylamine electron donors.Irradiation of chalcone epoxide 1 with triethylamine (TEA) afforded β-diketone 2 and β-hydroxy ketne 3.Photoreaction of 1 with TEA in MeOH resulted in a slightly increased product ratio (3/2) compared with that in MeCN.When 1,4-diazabicyclooctane (DABCO) was used instead of TEA, a decrease in the yield of 3 was observed.Only 2 was obtained on irradiation of a solution of 1 in TEA and MeCN containing LiClO4.Studies of photoreactions of dypnone epoxide 9, benzoylisopropylethylene epoxide 12, and acrylophenone epoxide 15 indicate that the nature of β-substituent also influences the product distribution.It was also found that 1,6-bis(dimethylamino)pyrene (BDMAP) sensitizes the photoreaction of 1 in the presence of TEA to produce 2.Based on the results obtained, a reaction mechanism involving selective Cα-O bond cleavage of intermediate α,β-epoxy ketone anion radicals is proposed.
- Hasegawa, Eietsu,Ishiyama, Kenyuki,Horaguchi, Takaaki,Shimizu, Takahachi
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p. 1631 - 1635
(2007/10/02)
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