- Chromium-Catalyzed Linear-Selective Alkylation of Aldehydes with Alkenes
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We developed a chromium-catalyzed, photochemical, and linear-selective alkylation of aldehydes with alkylzirconium species generated in situ from a wide range of alkenes and Schwartz's reagent. Photochemical homolysis of the C-Zr bond afforded alkyl radicals, which were then trapped by a chromium complex catalyst to generate the alkylchromium(III) species for polar addition to aldehydes. The reaction proceeded with high functional group tolerance at ambient temperature under visible-light irradiation.
- Hirao, Yuki,Kanai, Motomu,Katayama, Yuri,Mitsunuma, Harunobu
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supporting information
(2020/11/18)
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- Photochemical oxidation of benzylic primary and secondary alcohols utilizing air as the oxidant
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A mild and green photochemical protocol for the oxidation of alcohols to aldehydes and ketones was developed. Utilizing thioxanthenone as the photocatalyst, molecular oxygen from air as the oxidant and cheap household lamps or sunlight as the light source, a variety of primary and secondary alcohols were converted into the corresponding aldehydes or ketones in low to excellent yields. The reaction mechanism was extensively studied.
- Nikitas, Nikolaos F.,Tzaras, Dimitrios Ioannis,Triandafillidi, Ierasia,Kokotos, Christoforos G.
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supporting information
p. 471 - 477
(2020/02/13)
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- Olefin-assisted iron-catalyzed alkylation of aryl chlorides
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A selective and operationally simple ironcatalyzed cross-coupling of aryl chlorides with alkylmagnesium halides has been developed. The reaction tolerates various functional groups and exhibits high chemoselectivity even in the presence of aryl bromides. Mechanistic studies indicate the essential role of the olefin substituent for substrate activation. Competing polymerization and reduction are effectively suppressed.
- Guelak, Samet,Gieshoff, Tim N.,Von Wangelin, Axel Jacobi
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supporting information
p. 2197 - 2202
(2013/10/01)
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- Iron-catalyzed chemo- and stereoselective hydromagnesiation of diarylalkynes and diynes
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Diarylalkynes are chemo- and stereoselectively hydromagnesiated in high yields at room temperature with an iron species generated in situ from FeCl 2and EtMgBr. Functional groups such as bromide, iodide, amine, phenoxide, and alkene are well tolerated. Under similar conditions, diynes are chemo-, regio-, and stereoselectively hydromagnesiated. The resulting alkenylmagnesium compounds are a platform for further functionalization as a one-pot reaction.
- Ilies, Laurean,Yoshida, Takumi,Nakamura, Eiichi
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supporting information
p. 16951 - 16954,4
(2020/09/02)
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- Chromium(ii)-mediated reactions of iodonium tetrafluoroborates with aldehydes: Umpolung of reactivity of diaryl-, alkenyl(aryl)-, and alkynyl(aryl)iodonium tetrafluoroborates
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The method described herein allows us, for the first time, to perform umpolung of reactivity of diaryl-, alkenyl(aryl)-, and alkynyl(aryl)iodonium tetrafluoroborates. The method involves generation of organochromium(III) species via reaction of iodonium salts with anhydrous chromium dichloride, followed by their nucleophilic addition to aldehydes to yield alcohols. In contrast to the reaction of aryl and alkenyl halides with chromium dichloride, these iodonium salts are so active that organochromium(III) could be generated without using a nickel catalyst. Substituent effects of unsymmetrically substituted diaryliodonium salts on the product profiles are in good agreement with the reported mode of decomposition of the intermediate unsymmetrical diaryliodanyl radicals. Alkenyl(mesityl)iodonium tetrafluoroborates undergo exclusive alkenylation of aldehydes with no signs of the formation of an arylation product.
- Chen, Da-Wei,Ochiai, Masahito
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p. 6804 - 6814
(2007/10/03)
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- The first example for reactivity umpolung of diaryliodonium salts: Chromium(II)-mediated arylation of aldehydes
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Reported is the reactivity umpolung of diaryliodonium salts mediated by anhydrous chromium dichloride in the presence of a NiCl2 catalyst, which involves generation of an arylchromium(III) species, followed by the nucleophilic addition to aldehydes yielding benzyl alcohols.
- Chen, Da-Wei,Takai, Kazuhiko,Ochiai, Masahito
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p. 8211 - 8214
(2007/10/03)
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- Phenyl substituted-2,4,6,8-nonatetraenoic acid
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The compounds 9-phenyl-3,7-dimethyl-2,4,6,8 nonatetraenoic acids wherein the phenyl group is substituted with an alkyl, aminoalkyl, hydroxyalkyl, alkoxy, hydroxyalkylamino, and a hydroxy alkoxy group, and derivatives thereof which are used as disease modifying anti-rheumatic agents and as immunosuppressants.
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- Oxidation of sec-Alcohols to the Corresponding Ketones by Corynebacterium equi
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Corinebacterium equi IFO 3730 was found to oxidize a wide variety of sec-alcohols, including alkanols, substituted alkanols, alkenols and cyclic alcohols, in moderate to high yields.Among them, the sec-alcohols which have longer carbon chains were oxidized more smoothly than those with smaller numbers of carbon.Although both enantiomers of unsymmetrically disubstituted carbinols were oxidized, the S form of 2-dodecanol was converted to the corresponding ketone a little faster than the other enantiomer.
- Ohta, Hiromichi,Fujiwara, Hidenori,Tsuchihashi, Gen-ichi
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p. 1509 - 1516
(2007/10/02)
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