- Catalytic Reductive Cross-Coupling between Aromatic Aldehydes and Arylnitriles
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A reductive cross-coupling reaction between aromatic aldehydes and arylnitriles using a copper catalyst and a silylboronate as a reductant is reported. This protocol represents an unprecedented approach to the chemoselective synthesis of α-hydroxy ketones by electrophile–electrophile cross-coupling.
- Mitsui, Atsuhisa,Nagao, Kazunori,Ohmiya, Hirohisa
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supporting information
p. 7094 - 7098
(2021/04/16)
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- Oxidative [1,2]-Brook Rearrangements Exploiting Single-Electron Transfer: Photoredox-Catalyzed Alkylations and Arylations
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Oxidative [1,2]-Brook rearrangements via hypervalent silicon intermediates induced by photoredox-catalyzed single-electron transfer have been achieved, permitting the formation of reactive radical species that can engage in alkylations and arylations.
- Deng, Yifan,Liu, Qi,Smith, Amos B.
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supporting information
p. 9487 - 9490
(2017/07/24)
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- A Lewis acid-promoted reduction of acylsilanes to α-hydroxysilanes by diethylzinc
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We report here the first example of the reduction of acylsilanes to α-hydroxysilanes, in which diethylzinc was used as a highly reactive agent in the presence of Ti(OiPr)4 or other Lewis acids. The reduction typically proceeds to give synthetically useful α-hydroxysilanes in good yields.
- Gao, Guang,Bai, Xing-Feng,Li, Fei,Zheng, Long-Sheng,Zheng, Zhan-Jiang,Lai, Guo-Qiao,Jiang, Kezhi,Li, Fuwei,Xu, Li-Wen
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supporting information; experimental part
p. 2164 - 2166
(2012/05/05)
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- Metal-free relay oxidation: Valuable synthesis of acylsilane and ketones under aerobic oxidation
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In this letter, an example of interesting metal-free relay air oxidation of -hydroxysilanes, promoted by the hydroperoxidated carbonyl compounds derived from the Michael reaction of 5,5-dimethylcyclohexane-1,3-dione and chalcone, is reported. A series of aromatic acylsilanes with TBDPS were obtained in promising isolated yields. In addition, as an extension of the relay oxidation under aerobic conditions, this catalyst-free relay oxidation induced by diketone can be applied to the oxidation of general aromatic alcohols (up to 75% yield). Georg Thieme Verlag Stuttgart · New York.
- Bai, Xing-Feng,Gao, Guang,Zheng, Zhan-Jiang,Li, Fei,Lai, Guo-Qiao,Jiang, Kezhi,Li, Fuwei,Xu, Li-Wen
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p. 3031 - 3035
(2012/01/05)
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- Synthesis of Optically Pure Arylsilylcarbinols and Their Use as Chiral Auxiliaries in Oxacarbenium Ion Reactions
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A family of arylsilylcarbinols was synthesized and investigated as chiral auxiliaries for oxacarbenium ion reactions. The optically pure arylsilylcarbinols were prepared using Noyori's transfer hydrogenation catalyst 11. The transfer hydrogenation shows very good enantioselectivities and turnover efficiency for the aryl silyl ketones and is the method of choice for preparing these optically pure alcohols. The diastereoselective addition of allyltrimethylsilane to an in situ generated oxacarbenium ion was explored using Marko's conditions. The selectivity for a representative aliphatic aldehyde was very good, but the selectivity was significantly reduced with unsaturated and aromatic aldehydes. The range of selectivities with different auxiliaries was narrow, and the most practical auxiliary is the phenylsilylcarbinol 2.
- Huckins, John R.,Rychnovsky, Scott D.
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p. 10135 - 10145
(2007/10/03)
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- Synthetic utility and mechanistic studies of the aliphatic reverse brook rearrangement
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The aliphatic reverse Brook rearrangement has been examined in detail. Transmetalation of [α-[(trialkylsilyl)-oxy]alkyl]trialkylstannanes occurs via a complex equilibrium favoring the most stable carbanion. The aliphatic reverse Brook rearrangement is driven forward by the rapid migration of silicon from O to C in a transient α-silyloxy carbanion due to the formation of the more stable lithium alkoxide. Cross-over experiments have shown that the rearrangement is an intramolecular process while incorporation of a radical trap revealed that the rearrangement does not involve radical intermediates. Studies of configurationally fixed stannanes derived from 4-tert-butylcyclohexanone concluded that the rearrangement occurs with retention of configuration. Preparation and reverse Brook rearrangement of optically active (S)-[α-[(trimethylsilyl)oxy]-hexyl]tributylstannane (98% ee) provided 1-(trimethylsilyl)hexanol in 97% ee. The synthetic utility of this method for the preparation of a variety of (α-hydroxyalkyl)trialkylsilanes from aldehydes has also been demonstrated.
- Linderman, Russell J.,Ghannam, Ameen
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p. 2392 - 2398
(2007/10/02)
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- Reduction of Halosilanes by Organotin Hydrides
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A study of the reduction of halosilanes with organotin hydrides is described.The free radical chain mechanism indicated by the results obtained parallels that known for the comparable reduction of haloalkanes, but the reactivity of α-haloalkanes is considerable enhanced.Mechanistic studies suggest that the polar nature of the halogen abstraction step in the radical chain sequence, which places incremental negative charge adjacent to silicon, is the principal reason for this enhanced reactivity.Structure-reactivity studies indicat the gem-dimethylsilyl function to be an electronic transmitter.The ρ values for reduction of aryldimethyl(chloromethyl)silanes and substituted benzyl chlorides by tri-n-butyltin hydride are essentially identical (+0.45).Reduction of (chloromethyl)trimethylsiulane with aryldimethyltin hydrides, conversely, yielded a ρ value of -1.61.The reduction produced racemic product from an optically active α-chlorosilane, the synthesis of which appears to the first reported.Other syntheses of variuos halosilanes of interest are also described.The title reduction is specific for carbon-halogen bonds.Silicon-halogen bonds are not affected, a distinction that should make the reduction synthetically useful.Because the increased reactivity of α-halosilanes in the reduction has thus been ascribed to a kinetic polar effect in a critical step of the mechanism, no compelling argument for special thermodynamic stability in α-silyl radicals themselves can be made.
- Wilt, James W.,Belmonte, Frank G.,Zieske, Paul A.
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p. 5665 - 5675
(2007/10/02)
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