A new, practical route to enoxysilanes is described from simple enolizable aldehydes or ketones, using the trimethylchlorosilane-sodium iodide—tertiary amine reagent in acetonitrile. From certain aldehydes, an onium intermediate has been isolated. A conformational study of this onium intermediate and a thermal unimolecular syn-elimination process may explain the stereoselectivity of the reaction. Such
Depending on the steric hindrance of the reaction centers, hemiacetal vinylogs 1 in the presence of BF3.OEt2 can, with enol ethers, lead to a Michael-typeaddition (4) or an aldolisation-type reaction (3). Hemiacetal vinylog 1b always yields the second reaction leading to β-methoxy-γ,δ-ethylenic carbonyl compounds 4 precursors of polyenic carbonyl compounds 5. Crotonaldehyde and methanol can be used
Silver tetrafluoroborate induced reaction of trimethylsilyl enol ethers with 2,3-diiodo-1-(phenylsulfonyl)-1-propene as a method for preparing substituted furans
作者:Albert Padwa、Masaru Ishida
DOI:10.1016/s0040-4039(00)93526-3
日期:1991.10
Treatment of 2,3-diiodo-1-(phenylsulfonyl)-1-propene (DIP) with various trimethylsilyl enol ethers in the presence of silvertetrafluoroborate gives alkylation products derived from SN2 displacement of the terminal halide. These compounds readily cyclize with base to produce substituted furans.
在四氟硼酸银的存在下,用各种三甲基甲硅烷基烯醇醚处理2,3-二碘-1-(苯磺酰基)-1-丙烯(DIP),得到衍生自末端卤化物的S N 2的烷基化产物。这些化合物容易与碱环化以产生取代的呋喃。
A straightforward preparation of fluorine-containing 1,2-dihydropyrimidines and pyrimidines with 2,2-dihydropolyfluoroalkylaldehydes
作者:Xian-Jin Yang、Li-Si Zhang、Jin-Tao Liu
DOI:10.1016/j.tet.2007.04.010
日期:2007.6
The reactions of 2,2-dihydropolyfluoroalkylaldehydes with ammonia and enol ethers or carbonyl compounds are described. In the presence of zinc chloride, all reactions took place readily in THF at 50 °C to give fluorine-containing 1,2-dihydropyrimidines in moderate to good yields. Dehydrogenation of the resulting fluorine-containing 1,2-dihydropyrimidines with tetrachloro-1,4-benzoquinone (TCBQ) or
Nickel-catalyzed cross-coupling of silyl enol ethers with grignard reagents. Regio- and stereocontrolled synthesis of olefins
作者:Tamio Hayashi、Yoshio Katsuro、Makoto Kumada
DOI:10.1016/0040-4039(80)80215-2
日期:——
The substitution of the siloxy group in silyl enol ethers with Grignardreagents to form olefins is accomplished by use of nickel acetylacetonate or phosphine-nickelcomplexes as catalysts, the stereo- and regiochemistry of coupled olefins depending upon the nature of the catalyst and reaction conditions employed.