- First examples of hypervalent enhancement of photoallylation by allylsilicon compounds via photoinduced electron transfer
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Hypervalency (pentacoordination) of silicon atom enhanced photoallylation of 1,2-diketones with allylsilicon reagents, while normal tetracoordinated ones could not. This reaction seems to proceed via photoinduced electron transfer from the silicon reagent
- Nishigaichi, Yutaka,Suzuki, Akira,Saito, Takahiro,Takuwa, Akio
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Read Online
- COMPLEXES AND CATALYTIC PROCESSES
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The present application is directed towards complexes of formula (I), to methods for preparing such complexes, and to use of such complexes in catalysis. The complexes show utility in a range of catalytic cycles, including Pd(ll)/Pd(IV) cycles. (Formula (I))
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Page/Page column 48; 49
(2015/06/25)
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- Photo-allylation and photo-benzylation of carbonyl compounds using organotrifluoroborate reagents
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Allyl- and benzyl-trifluoroborates can be applied to the photoreaction of carbonyl compounds to afford the corresponding alcoholic adducts in acceptable yields via a photo-induced single electron transfer pathway. The results were confirmed from the react
- Nishigaichi, Yutaka,Orimi, Takayuki,Takuwa, Akio
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experimental part
p. 3837 - 3839
(2010/03/04)
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- Assembly of functionalized α-hydroxy carbonyl compounds via combination of N-heterocyclic carbene and Pd catalysts
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Functionalized α-hydroxy carbonyl compounds were prepared from various aldehydes and allylic acetates via a multicomponent reaction, which were catalyzed by N-heterocyclic carbene and Pd catalysts in one pot.
- He, Jinmei,Tang, Shibing,Tang, Shouchu,Liu, Jian,Sun, Yongquan,Pan, Xinfu,She, Xuegong
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experimental part
p. 430 - 433
(2009/05/11)
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- Palladium-catalyzed C-allylation of benzoins and an NHC-catalyzed three component coupling derived thereof: Compatibility of NHC- and Pd-catalysts
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(Chemical Equation Presented) A large range of benzoins was successfully applied as C-nucleophiles in the palladium-catalyzed allylic alkylation with several allyl acetates, resulting in functionalized tertiary homoallylic alcohols. A number of unsymmetrical benzoins can be coupled with high levels of regio- and chemoselectivity. Finally, the challenging compatibility of free N-heterocyclic carbenes with a palladium catalyst has been utilized in a number of metal- and organocatalyzed three-component coupling reactions.
- Lebeuf, Raphael,Hirano, Keiichi,Glorius, Frank
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scheme or table
p. 4243 - 4246
(2009/06/06)
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- Remarkable enhancement of photo-allylation of aromatic carbonyl compounds with a hypervalent allylsilicon reagent by donor molecules
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Photo-allylation of various aromatic carbonyl compounds with a penta-coordinated allylsiliconate reagent was remarkably accelerated by the addition of a donor molecule. As the oxidation potential of the allylsiliconate was significantly decreased in the p
- Nishigaichi, Yutaka,Suzuki, Akira,Takuwa, Akio
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p. 211 - 214
(2007/10/03)
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- Highly regio- and stereoselective allylation of α-diketones via the fluorosilicate route
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A1lylation of enolizable α-diketones with allyltrifluorosilanes in the presence of triethylamine gave the corresponding tertiary homoallyl alcohols in good yield in a highly regio- and stereospecific manner. The reaction proceeds as diallylation with allyltrifluorosilanes yielding the 1,2-diols with high diastereoselectivity. The more sterically demanding crotyl- and prenyltrifluorosilanes lead exclusively to monoallylated products with the allyl group being added γ-regioselectively. In addition, highly diastereoselective crotylation was observed in the formation of the monoallylated α-hydroxy ketones. Asymmetric α-diketones were generally allylated at the less enolized ketone group except when both diketone and allylsilane were sterically hindered.
- Gewald, Rainer,Kira, Mitsuo,Sakurai, Hideki
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p. 111 - 115
(2007/10/03)
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- Photochemically Induced Single Electron Transfer Reactions of Benzils with Allylstannane. Direct Observation of Reactive Intermediates by ESR Method
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Allthough the photochemically induced reaction of benzil with allyltrimethylstannane in benzene afforded α-allylbenzoin as a major product, benzil did not react thermally with the same reagent.An ESR observation disclosed that the benzil anion radical ion
- Maruyama, Kazuhiro,Matano, Yoshihiro
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p. 2218 - 2223
(2007/10/02)
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- Allylation of α-Diketones by Photochemical Reactions with Allylic Stannanes. Regiochemistry of Introduced Allylic Group
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Irradiation of an acetonitrile solution of benzils and acenaphthenequinone in the presence of allylic stannanes afforded homoallylic alcohols in good yields.In the reaction with unsymmetric allylstannanes, the allylic groups were introduced predominantly at α-positions.The completely regioselective introduction could be achieved by the irradiation in the presence of NaOH or CoCl2 as an additive.
- Takuwa, Akio,Nishigaichi, Yutaka,Yamashita, Koichi,Iwamoto, Hidetoshi
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p. 639 - 642
(2007/10/02)
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- Palladium-Catalyzed Carbonyl Allylation of Diketo Compounds by Allylic Alcohols with SnCl2
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Palladium-catalyzed diallylation of 1,2-diketones and 1,2-ketoaldehyde by allylic alcohol with SnCl2 in DMI was accelerated and proceeded diastereoselectively thanks to a chelation of a carbonyl group to Sn(IV) (tin alkoxide) in the corresponding monoallylated intermediates.
- Masuyama, Yoshiro,Tsunoda, Tomoyoshi,Kurusu, Yasuhiko
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p. 1647 - 1650
(2007/10/02)
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- The Reaction of Benzil with Grignard Reagents
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Benzil reacts with Grignard reagents forming, in the first step, the 1,2-addition product (C-alkylation), but often also the 1,4-addition product (O-alkylation) and the reduction product, benzoin.The product distribution has been determined for mechanistic purposes for 16 Grignard reagents using a standard procedure.These results, and observations made using deuteriated reagents and the 5-hexenyl radical probe indicate an electron transfer (ET) mechanism for reagents having hydrogen in the β-position, while a polar mechanism is the most efficient for methyl, phenyl, benzyl and allyl Grignard reagents in the ether solution.For the ET mechanism, a six-centre transition state is suggested.Furthermore, a distinction is made between the primary cage product (O-alkyl) resulting from immediate combination of the radical pair, and the secondary cage product (C-alkyl) formed in the cage after rearrangement. 5-Hexenylmagnesium bromide yields uncyclised primary and secondary cage product, but also significant amounts of cyclised C-alkylation product formed by escape of the radicals from the cage and re-encounter after cyclisation of 5-hexenyl to cyclopentylmethyl.A recently suggested mechanism based on the existence of stable radical ion pairs is found to be unacceptable.
- Holm, T.
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p. 278 - 284
(2007/10/02)
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- Acylsilanes and C-Stannylimines as Anion Equivalents
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Acylsilanes and C-stannylimines react with organic halides in the presence of KF-18-crown-6 ether to give ketones and ketimines, respectively.
- Degl'Innocenti, Alessandro,Pike, Stephen,Walton, David R. M.,Seconi, Giancarlo,Ricci, Alfredo,Fiorenza, Mariella
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p. 1201 - 1202
(2007/10/02)
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- Novel chelate formers
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Benzoin oximes of the formula STR1 wherein R1 is alkyl of 3 to 16 carbon atoms, alkenyl of 3 or 4 carbon atoms, 3,7-dimethyl-2,6-octadienyl-1, or -A-S-R4 ; R2 and R3 independently are H, methyl or chlorine; R4 is alkyl or 1 to 8 carbon atoms; and A is alkylene of 3 or 4 carbon atoms, are chelating agents for copper.
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- α-(Cyanoethyl)-benzoin ethers
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The invention relates to racemates of the formula (I) SPC1 in which R1 and R2 are hydrogen, lower alkyl, methoxy, ethoxy or halogen, R3 is unsubstituted alkyl or lower alkyl substituted with alkoxy carbonyl carbonamido, cyano or hydroxyl or unsubstituted alkenyl or alkenyl substituted with halogen or halogen-, methyl-, ethyl-, methoxy- or ethoxy-substituted phenyl or unsubstituted cycloalkyl or cycloalkyl substituted with lower alkyl or unsubstituted phenylalkyl or phenylalkyl, the phenyl nucleus of which being substituted with methyl, methoxy, halogen or nitro, and R4 is unsubstituted alkyl or alkenyl or unsubstituted cycloalkyl or cycloalkyl substituted with lower alkyl or unsubstituted phenyl or phenyl substituted with lower alkyl methoxy, ethoxy or halogen or unsubstituted phenylalkyl or phenylalkyl, the phenyl nucleus of which being substituted with methyl, methoxy or halogen and X is oxygen or sulphur, Which are useful as photosensitizers for light induced polymerisations of vinyl monomers as well as for the light induced crosslinking of unsaturated polycondensates and polymers.
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