- Iron-catalyzed carbonylation-peroxidation of alkenes with aldehydes and hydroperoxides
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A three-component reaction of alkenes, aldehydes, and hydroperoxides catalyzed by FeCl2 to β-peroxy ketones has been achieved. This three-component reaction can be also applied to the synthesis of α-carbonyl epoxides, through either a stepwise base-induced epoxidation of the separated β-peroxy ketone products or a one-pot process by simply adding base to the reaction mixture after the completion of the three-component reaction.
- Liu, Weiping,Li, Yuanming,Liu, Kaisheng,Li, Zhiping
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p. 10756 - 10759
(2011/08/22)
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- Stereoselective synthesis of 3,5-dialkyl-3,5-dihydro-3,5-diphenyl-4H- pyrazol-4-ones
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We report stereoselective five-step syntheses of cis-3-ethyl-3,5-dihydro-3, 5-diphenyl-5-methyl-4H-pyrazol-4-one (cis-1b) and trans-3,5-diethyl-3,5-dihydro- 3,5-diphenyl-4H-pyrazol-4-one (trans-1c). The key synthon was 1,3-diphenylpent-2-en-1-one (5b) synthesized in a new one-pot crossed aldol/dehydration reaction of acetophenone with propiophenone using titanium(IV) chloride/tributylamine, followed by treatment with methanesulfonyl chloride and triethylamine. Georg Thieme Verlag Stuttgart.
- Moiseev, Andrey G.,Neckers, Douglas C.
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p. 2901 - 2905
(2007/10/03)
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- Synthesis, Structure, and Sterreoselective Reaction of a Chiral Hydroxy-Stabilized Metal-Free Enolate
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The reaction of acetophenone with tetrabutylammonium hydroxide affords the tetrabutylammonium enolate of phenyl (2-hydroxy-2-phenyl)propyl ketone.The crystal structure of this chiral enolate shows intramolecular hydrogen bonding between the hydroxyl group and the enolate oxygen atom.Furthermore, the α-methylene units of the ammonium counterion form hydrogen bonds to the basic enolate C and O atoms and to the O atom of the hydroxy group.This three-point bonding occurs selectively on the Re,Re side, a phenomenon which may be responsible for the direction of diastereoselectively in the epoxide-forming reaction of the enolate with N-bromosuccinimide. - Keywords: asymmetric synthesis; chirality; enolates; hydrogen bonds; structure elucidation
- Reetz, Manfred T.,Huette, Stephan,Goddard, Richard,Robyr, Chantal
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p. 382 - 384
(2007/10/03)
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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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