Regioselective allylation of enol silyl ethers with γ-heterosubstituted vinylthionium ions
作者:Roger Hunter、Joseph P. Michael、Daryl S. Walter
DOI:10.1016/s0040-4039(00)73530-1
日期:1994.7
γ-Heterosubstituted vinylthioniumions regioselectively and diastereoselectively allylate enolsilylethers. Intramolecular capture of a vinylthioniumion is used as a key step of a novel pentannulation sequence.
[3-(Ethylthio)allyl]titanium reagent generated easily from allyl ethyl sulfides condensed with aldehydes to give erythro-β-hydroxy sulfides in highly regio- and stereoselective manner. In contrast, crotyl ethyl sulfide reacted with aldehydes affording δ-hydroxy vinyl sulfide exclusively. The substitution pattern of the starting sulfide can have a pronounced effect on the selectivity in this condensation reaction
2-(2-Pyridyl)ethylsilyl Group as a New Class of Electroauxiliary. Fine Tuning of the Electron Transfer Driven Reactions by the Dynamic Coordination to Silicon
The introduction of 2-(2-pyridyl)ethyl group on silicon decreases the oxidation potentials of silyl-substituted heteroatom compounds. The molecular orbital calculations indicate that this effect is attributed to the dynamic coordination of the pyridyl group to silicon in the cation radical intermediate. Such coordination also facilitates the selective C-Si bond cleavage.
Reactions of phenylthiotrimethylsilylmethyllithium: Preparation of α-phenylthioketones and additions to 2-cyclohexen-1-one
作者:David J Ager
DOI:10.1016/s0040-4039(01)90557-x
日期:1981.1
Phenylthiotrimethylsilylmethyllithium(1) was reacted with a variety of electrophiles, including somecontaining two functional groups. α-Phenylthiolketones were obtained from the reaction with esters. The anion(1) underwent either 1,2- or 1,4-addition, depending on the conditions used, with 2-cyclohexen-1-one.