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
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.
Oxidation reactions catalysed by titanium- and chromium-containing silicalites
作者:Satya V. N. Raju、T. T. Upadhya、S. Ponrathnam、T. Daniel、A. Sudalai
DOI:10.1039/cc9960001969
日期:——
While the titanium silicalite-1 (TS-1)–tert-butyl hydroperoxide (TBHP) combination exhibits remarkable activity and selectivity in the oxidative cleavage of the C–C double bond of silyl enol ethers to produce dicarboxylic acids, the chemoselective oxidation of thioethers to sulfoxides without generation of sulfones is achieved using chromium silicalite-2 (CrS-2)–H2O2.
Synthesis of Siloxy-α-Lapachone Derivatives by Chemo- and Regioselective Diels-Alder Reactions of 3-Methylene-1,2,4-naphthotriones with Silyl Enol Ethers
2-hydroxy-1,4-naphthoquinone with aliphatic and aromatic aldehydes, take part in chemoselective hetero-Diels-Alder reactions with silyl enolethers to give a series of siloxy-containing naphtho[2,3- B]pyran-5,10-dione (α-lapachone) derivatives in moderate to high yield. These reactions regio-selectively gave α-lapachone derivatives with an acetal structure. This regioselectivity can be rationalized by
Kinetic resolution in asymmetric anti aldol reactions of branched and straight chain racemic 2-phenylsulfanyl aldehydes: asymmetric synthesis of cyclic ethers and lactones by phenylsulfanyl migration
作者:Kelly Chibale、Stuart Warren
DOI:10.1039/p19960001935
日期:——
The kinetic resolution of branched and straight chain 2-phenylsulfanyl aldehydes by the Lewis acid-catalysed asymmetric anti aldol reaction followed by reduction to single enantiomers of 1,3-diols and/or acid-catalysed cyclisation with PhS migration provides a route to enantiomerically pure cyclic ethers and lactones with full stereochemical control.