- Carboazidation of chiral allylsilanes: Experimental and theoretical investigations
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The carboazidation of chiral allylsilanes has been investigated by varying the nature of the substituents at the silicon center and on the carbon framework. The influence of temperature and the nature of the sulfonyl azide, as well as the stereochemistry of the remote stereogenic center, on the 1,2-diastereocontrol of the process were considered. Good to excellent levels of diastereocontrol were generally observed, with the syn-β-azidosilane always being formed as the major isomer. An illustration of the value of this methodology has been provided with a short and efficient synthesis of an analogue of castanospermine. EPR spectroscopy was carried out on various β-silyl radicals providing useful information about their conformations in the ground state. Based on this experimental evidence and DFT calculations, reactant-like transition state models were finally proposed that rationalize the observed 1,2-stereoinduction.
- Chabaud, Laurent,Landais, Yannick,Renaud, Philippe,Robert, Frederic,Castet, Frederic,Lucarini, Marco,Schenk, Kurt
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supporting information; experimental part
p. 2744 - 2756
(2009/04/08)
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- ORGANIC SYNTHESIS WITH REAGENTS DERIVED FROM 3R3SiMgMe AND MnCl2
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Synthetically useful reactions mediated by reagents derived from 3 equiv. of R3SiMgMe and MnCl2 are disclosed. (1) The manganese species reacted with terminal acetylenes to give 1,2-disilylated 1-alkenes.Mono- and bis(trimethylsilyl)acetylenes gave tri- a
- Fugami, Keigo,Hibino, Jun-ichi,Nakatsukasa, Shigeki,Matsubara, Seijiro,Oshima, Koichiro,et al.
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p. 4277 - 4292
(2007/10/02)
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- NEW SYNTHESES OF VINYLSILANES AND ALLYLSILANES BY CROSS-COUPLING OF (R3Si)3MnMgMe WITH ALKENYL AND ALLYLIC COMPOUNDS
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The reaction of alkenyl halides, alkenyl sulfides, and enol phosphates with (R3Si)3MnMgMe provides vinylsilanes in good yields.The method is also applicable to the allylsilane synthesis from allylic sulfides and ethers.
- Fugami, Keigo,Oshima, Koichiro,Utimoto, Kiitiro,Nozaki, Hitosi
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p. 2161 - 2164
(2007/10/02)
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- REACTION OF (BROMODIFLUOROMETHYL)PHENYLDIMETHYLSILANE WITH ORGANOMETALLIC REAGENTS
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A new fluorine-containing organosilicon compound, (bromodifluoromethyl)phenyldimethylsilane (II), was synthesized by the N-bromosuccinimide (NBS) bromination of (difluoromethyl)phenyldimethylsilane (I), which was prepared from phenyldimethylsilyllithium and chlorodifluoromethane.Compound II reacted with dimethyl sulfoxide to give dimethyl sulfide and phenyldimethylfluorosilane in quantitative yield.The reaction of II with nucleophiles, such as sodium ethoxide, Grignard or lithium reagents, afforded products arising from cleavage of the carbon-silicon bond.In contrast, the reaction of II with Grignard reagents in the presence of appropriate catalysts (Group VIII transition metal salts or complexes) afforded the homo-coupling product of II, 1,2-bis(phenyldimethylsilyl)-1,1,2,2-tetrafluoroethane (IV), in excellent yield.The silver(I) salt-catalyzed reaction of II with ethylmagnesium bromide gave the cross-coupling product, (1,1-difluoropropyl)phenyldimethylsilane (V) as well as III and IV.When cuprous bromide was employed as catalyst, the reaction of II with ethylmagnesium bromide afforded 1-phenyldimethylsilyl-1-propene (VI) and 3-phenyldimethylsilyl-2-pentene (VII) as main products.
- Fuchikami, Takamasa,Ojima, Iwao
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p. 145 - 153
(2007/10/02)
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