α-alkylation and α-alkylidenation of carbonyl compounds by o-silylated enolate phenylthioalkylation
作者:Ian Paterson
DOI:10.1016/s0040-4020(01)86667-9
日期:1988.1
For many reactions next to a carbonyl group, the use of O-silylated enolatechemistry offers improvements in yield and selectivity over the corresponding reactions of Group I metal enolates. In the case of α-alkylation of carbonylcompounds, Lewis-acid (TiCL4 or ZnBr2) promoted phenylthioalkylation of O-silylated enolates 3 by α-chlorosulphides 4 (R3=H, Me, Prn, Pri, But, and Me3Si), followed by reductive
The synthesis of αβ-unsaturated ketones from β-silylenones and β-silylynones
作者:Ian Fleming、David A. Perry
DOI:10.1016/s0040-4020(01)93277-6
日期:——
Conjugate addition, followed by alkylation, bromination and desilyl-bromination make the β-silylketone (4) an a3d3-synthon (5) and the β-silylynone (6) a 2a3d3-synthon (7).
共轭加成,然后进行烷基化,溴化和去甲硅烷基溴化反应,使β-甲硅烷基酮(4)成为3 d 3-合成子(5)和β-甲硅烷基酮(6)成为2a 3 d 3-合成子(7)。
Carbonium ion rearrangements controlled by the presence of a silyl group
作者:Ian Fleming、Shailesh K Patel
DOI:10.1016/s0040-4039(01)92922-3
日期:——
Tertiary alcohols with a λ-silyl group (3) generally undergo a simple carboniumionrearrangement in acid giving a single alkene product (4) with loss of the silyl group.
The fluoride-induced reaction of phenylthio-, methylthio- and methoxy-substituted silylmethylazoles with carbonyl compounds
作者:Sumio Shimizu、Masaru Ogata
DOI:10.1016/0040-4020(89)80092-4
日期:1989.1
Phenylthio-, methylthio- and methoxy-substitutedsilylmethylazoles, which act as substituted (N-azolyl)methylanion equivalents, were prepared and made to react with carbonylcompounds in the presence of fluoride anion to obtain 2-phenylthio-, 2-methylthio- and 2-methoxy-substituted 2-azolylethanols. Also examined in this study was the lithiation of 1-methylthiomethyl-1,2,4-triazole and 1-bis(methylthio)methyl-1
ethylsilanes 12 by base-induced α-elimination. This is confirmed by [2+1] cycloadditions with alkenes to give the cyclopropanes 4a–d and 14. Product 4a is identical with the product obtained from carbanion 1c, phenyloxirane, and styrene, for which a carbene intermediate 5a had been invoked. On heating in the presence of copper triflate, cyclopropane 4a undergoes ringenlargement to the thiochroman