- Pyridyl group assisted deprotonation of a methyl group on silicon: Complex induced proximity effect and novel hydroxymethylation
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A novel methodology for the deprotonation of a methyl group on silicon has been developed. This newly developed α-lithiation protocol is based on the intramolecular pyridyl group coordination to stabilize the α-silyl carbanion together with the inherent silicon α effect. It was found that the deprotonation (t-BuLi/Et2O/-78 °C) occurs with 2-pyridyltrimethylsilane but not with other related silanes such as phenyltrimethylsilane, 3-pyridyltrimethylsilane, and 4-pyridyltrimethylsilane. It seems that this deprotonation proceeded through the agency of the complex-induced proximity effect (CIPE) of a 2-pyridyl group on silicon. 1H NMR analysis of (2-pyridyldimethylsilyl)methyllithium revealed the intramolecular coordination of a pyridyl group to lithium. (2-Pyridyldimethylsilyl)-methyllithium was found to react with chlorosilanes, hydrosilanes, chlorostannanes, bromine, iodine, organic bromides, aldehydes, and ketones in good to excellent yields. The resultant adducts were further oxidized with H2O2/KF to give the corresponding alcohols in excellent yields. Thus, this two-step transformation provides an efficient method for the nucleophilic hydroxymethylation.
- Itami,Kamei,Mitsudo,Nokami,Yoshida
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p. 3970 - 3976
(2007/10/03)
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- Facile generation of [bis(2-pyridyldimethylsilyl)methyl]lithium and its reaction with carbonyl compounds. New method for the stereoselective synthesis of vinylsilanes
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The generation of (2-PyMe2Si)2CHLi was easily accomplished by the deprotonation of (2-PyMe2Si)2CH2 using n-BuLi in Et2O. The 1H NMR analysis of (2-PyMe2Si)2CHLi in Et2O-d10 revealed the coordination of both pyridyl groups to lithium. Thus generated (2-PyMe2Si)2CHLi was found to react with a variety of aldehydes and ketones to give the corresponding vinylsilanes in extremely high yields with complete stereoselectivities (>99% E).
- Itami, Kenichiro,Nokami, Toshiki,Yoshida, Jun-Ichi
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p. 5045 - 5054
(2007/10/03)
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- [Bis(2-pyridyldimethylsilyl)methyl]lithium. New reagent for the stereoselective synthesis of vinylsilanes
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(formula presented) The generation of (2-PyMe2Si)2CHLi was easily accomplished by the deprotonation of (2-PyMe2Si)2CH2 using n-BuLi in Et2O. Thus generated (2-PyMe2Si)2/sub
- Itami, Kenichiro,Nokami, Toshiki,Yoshida, Jun-Ichi
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p. 1299 - 1302
(2007/10/03)
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- (2-Pyridyldimethylsilyl)methyl lithium as a novel hydroxymethylating reagent
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(2-Pyridyldimethylsilyl)methyl lithium was found to react with organic bromides, aldehydes, ketones, and hydrosilanes in good to excellent yields. The resultant adducts were further oxidized with H2O2/KF to give the corresponding alcohols in excellent yields. Thus, this two-step transformation provides an efficient method for hydroxymethylation.
- Itami, Kenichiro,Mitsudo, Koichi,Yoshida, Jun-ichi
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p. 5537 - 5540
(2007/10/03)
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