Titanocene(III)-Catalyzed 6-<i>exo</i>Versus 7-<i>endo</i>Cyclizations of Epoxypolyprenes: Efficient Control and Synthesis of Versatile Terpenic Building Blocks
作者:José Justicia、Tania Jiménez、Delia Miguel、Rafael Contreras-Montoya、Rachid Chahboun、Enrique Álvarez-Manzaneda、Daniel Collado-Sanz、Diego J. Cárdenas、Juan M. Cuerva
DOI:10.1002/chem.201302575
日期:2013.10.18
In this article, a complete study on the selectivity of titanocene(III) cyclization of epoxypolyprenes is presented. The requirements for the formation of six‐ or seven‐membered rings during these cyclizations are determined, taking into account the different substitution pattern in the epoxypolyprene precursor. Thus, a complete selectivity to 6‐exo or 7‐endo cyclization process has been achieved,
The orthoester Johnson–Claisen rearrangement of allylic terpenols in the presence of acidic ionic liquid
作者:Galina V. Kryshtal、Galina M. Zhdankina、Nikolai V. Ignat’ev、Michael Schulte、Sergei G. Zlotin
DOI:10.1016/j.jfluchem.2016.01.005
日期:2016.3
A convenient protocol for the synthesis of natural isoprenoid-derived carboxylic esters via reaction of allylic terpenols with triethyl orthoacetate (propionate) in the presence of 1-butyl-3-methylimidazolium hexafluorophosphate, [bmim][PF6] (10 mol%), has been developed. The desired terpene derivatives were prepared in moderate to high yield. The ionic liquid (IL) can be easily separated from the
Reduction of 1-hexene with Cp3Ln/NaH (Cp = cyclopentadienyl, Ln = rare earth metals) in THF at 45°C, after hydrolysis, gives hexane. The reducing activity of Cp3Ln depends strongly upon the ionic radius of the trivalent rare earth ion. The activity and selectivity of early rare earths for 1-hexane reduction are higher than those of heavy rare earths. The Cp3Ln/NaH systems can be used to regioselectively
Electrochemical oxidation of organosilicon compounds I. Oxidative cleavage of carbon-silicon bond in allylsilanes and benzylsilanes
作者:Jun-ichi Yoshida、Toshiki Murata、Sachihiko Isoe
DOI:10.1016/s0040-4039(00)84799-1
日期:1986.1
Electrochemical oxidation of allylsilanes and benzylsilanes in the presence of alcohol, carboxylic acid, or water resulted in cleavage of the carbon-siliconbond and formation of the corresponding ether, ester, or alcohol, respectively.
A Novel Method for the Preparation of Acid-Sensitive Epoxides from Olefins with the Combined Use of Molecular Oxygen and Aldoacetal Catalyzed by a Cobalt(II) Complex
An efficient synthesis of acid-sensitive epoxides, such as chromene oxide or epoxide of γ,δ-unsaturated alcohol, was successfully achieved by the oxygenation of corresponding olefins with the combined use of an atmospheric pressure of molecular oxygen and aldoacetal catalyzed by a cobalt(II) complex coordinated with the 1,3-diketone ligand. The reactions proceeded under mild and neutral conditions