- 2-Norbornyldimethylsilyl ethers (NDMS): A new protecting group for alcohols and carboxylic acids
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The use of the readily available 2-norbornyldimethylsilyl group (NDMS) in the protection of alcohols and carboxylic acids is described. Stabilities of the corresponding silyl compounds towards various reagents and deprotection conditions are compared with tert-butyldimethylsilyl-, iso-propyldimethyl and trimethylsilyl groups.
- Heldmann, Dieter K.,Stohrer, Jürgen,Zauner, Rafael
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- Metal complex and supported metal complex having disiloxane as ligand, method for production therefor, and supported metal catalyst prepared by using the same
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A metal complex represented by the following Formula (1): (wherein M represents palladium or platinum; L represents a ligand selected from carbon monoxide, an olefin compound, an amine compound, a phosphine compound, an N-heterocyclic carbene compound, a nitrile compound and an isocyanide compound; n represents an integer of 0 to 2 showing the number of the ligand; and each of R1 to R4 represents an organic group). The metal complex described above can be fixed on an inorganic oxide while maintaining a skeletal structure thereof to obtain a supported metal complex, and this makes it possible to allow the supported metal complex to maintain the same catalytic activity as that of the original metal complex. Also, calcining the supported metal complex obtained in the manner described above makes it possible to obtain a supported metal catalyst which is improved in catalytic activity to a greater extent than conventional supported metal catalysts.
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Page/Page column 15
(2019/03/17)
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- Utilization of a Trimethylsilyl Group as a Synthetic Equivalent of a Hydroxyl Group via Chemoselective C(sp3)-H Borylation at the Methyl Group on Silicon
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A conversion of trimethylsilylalkanes into the corresponding alcohols is established based on an iridium-catalyzed, chemoselective C(sp3)-H borylation of the methyl group on silicon. The (borylmethyl)silyl group formed by C(sp3)-H borylation is treated with H2O2/NaOH, and the resulting (hydroxymethyl)silyl group is converted into a hydroxyl group by Brook rearrangement, followed by oxidation of the resulting methoxysilyl group under Tamao conditions. An alternative route proceeding through the formylsilyl group formed from a (hydroxymethyl)silyl group by Swern oxidation is also established. The method is applicable to substituted trimethylsilylcycloalkanes and 1,1-dimethyl-1-silacyclopentane for conversion into the corresponding stereodefined cycloalkyl alcohols and 1,4-butanediol.
- Torigoe, Takeru,Ohmura, Toshimichi,Suginome, Michinori
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p. 2943 - 2956
(2017/03/23)
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- Use of carboxylated polyethylene glycol as promoter for platinum-catalyzed hydrosilylation of alkenes
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Several carboxylated polyethylene glycols as promoters were applied in the platinum-catalyzed hydrosilylation of alkenes, and polyethylene glycol maleic acid monoester as a promoter for hydrosilylation was investigated. It was found that an improvement of the selectivity was achieved in the presence of carboxylated polyethylene glycol, and the β-adduct as major product was obtained. Additionally, the effect of alkenes and silanes employed on the selectivity was investigated; better selectivity could be achieved when (EtO)3SiH was used as the hydride than ClMe2SiH.
- Bai, Ying,Peng, Jiajian,Li, Jiayun,Lai, Guoqiao
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experimental part
p. 400 - 405
(2012/04/17)
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- Effects of Proximate Polar Groups on the Rates of Hydrosilylation
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Endo-, exo-, and trans-2,3-disubstituted bicyclohept-5-enes were found to react with dimethylchlorosilane in the presence of a platinum catalyst to yield the corresponding 5-silyl derivatives.The reaction of the endo anhydride proceeded in high yield, although quite slowly.The exo anhydride was found to react faster than the analogous endo epimer.Furthermore, the endo N-phenylimide did not react under these conditions, while the exo N-phenylimide epimer reacted rapidly and in high yield.A similar ordering of reactivity was observed with the endo-, trans-, and exo-2,3-dicarbomethoxybicyclohept-5-enes.Silicon was found exclusively on the exo face of the bicycloheptyl skeleton, remote from substituents at the 2,3-positions.Purely steric arguments are insufficient to explain the anomalous reactivity of the endo anhydride and endo N-phenylimide.However, the reactivity differences can be rationalized in terms of field effects exerted by the electron-deficient anhydride and imide rings.
- Eddy, Victoria J.,Hallgren, John E.
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p. 1903 - 1906
(2007/10/02)
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