Synthesis of 4(benzyloxymethyl)(tert.-butyl)methylsilyloxy-1,2,3-pentatriene via Brook rearrangement
作者:Stefan Bienz、Valentin Enev、Priska Huber
DOI:10.1016/0040-4039(94)88012-3
日期:1994.2
1-lithium-3-tetrahydropyranyloxy-1-propyne with (benzyloxymethyl)-(tert.-butyl)methylsilyl methyl ketone gave rise to the corresponding α-silylated propargylic alcoholate anion, which led in a succession of Brookrearrangement and 1,4-elimination to the title compound in good yield.
Preparation of a `Si-centered' chiral auxiliary by resolution
作者:Michael Trzoss、Jie Shao、Stefan Bienz
DOI:10.1016/j.tetasy.2004.03.014
日期:2004.5
(R)- and (S)-[(benzyloxy)methyl](tert-butyl)methylsilane [(−)-(R)-1 and (+)-(S)-1], possessing a stereogenic center at the Si-atom, were prepared in highly enantiomerically enriched form by resolution via diastereomeric silyl ethers. Conversion of the hydrosilanes into different functionalized chiralsilanes by direct or stepwise substitution of the (Si)–H-atom was shown to proceed with high stereoselectivity
Chiral silicon groups as auxiliaries for enantioselective synthesis: access to optically active silanes by biotransformation and the enantiospecific preparation of (R)-(+)-1-phenylethanol
The synthesis of the opticallyactive alkoxymethyl-substituted acetylsilanes (+)-3 and (−)-b was achieved by the bioreduction of (±)-3 with resting cells of Trigonopsis variabilis to the diastereoisomeric alcohols (+)-4 and (+)-5. These two compounds were separated by chromatography and separately reoxidized to the desired opticallyactive silyl ketones. As a simple example of the use of chiral al
Chiral Acylsilanes in Organic Synthesis. Part 2. The role of the solvent, the organometallic reagent, and the nature of the substrate for the diastereoselectivity of 1,2-additions to racemic alkoxymethyl-substituted acylsilanes
作者:Alexander Chapeaurouge、Stefan Bienz
DOI:10.1002/hlca.19930760507
日期:1993.8.11
The role of the solvent, the organometallicreagent, and the nature of the substrate for the diastereoselectivity of 1,2-additions to racemicalkoxymethyl-substitutedacylsilanes was investigated with the acylsilanes 1a–d by variation of the reaction parameters. The results obtained in this study support strongly the previously proposed preferred ‘chelate-controlled’ reaction path followed under several
stituted 1,3-dithianes show in CI-MS an abundant loss of benzaldehyde from the [M + H]+ quasi-molecular ion. The fragmentation is explained with an intramolecular redox process, where a hydride is proposed to be transferred from the benzyl position to a neighboring thionium ion. This would form a particle that could readily lose benzaldehyde as a neutral fragment. The CI-MS results provide an explanation
[(苄氧基)甲基]二烷基甲硅烷基取代的1,3-二硫杂环丁烷在CI-MS中显示,苯甲醛从[ M + H] +准分子离子中大量损失。用分子内氧化还原过程解释了该断裂,其中提议将氢化物从苄基位置转移至相邻的硫鎓离子。这将形成易于失去作为中性片段的苯甲醛的颗粒。CI-MS结果为(苄氧基)甲基取代的硅烷对酸的异常不稳定性提供了解释。实际上,在路易斯或布朗斯台德的存在下,(苄氧基)甲基取代的酰基硅烷的分解建立了苯甲醛的形成。酸和乙硫醇。因此,CI-MS研究代表了一种有用的方法,可以识别对解决方案非常重要的异常反应。