An Efficient Synthesis of Organic Carbonates using Nanocrystalline Magnesium Oxide
作者:M. Lakshmi Kantam、Ujjwal Pal、B. Sreedhar、B. M. Choudary
DOI:10.1002/adsc.200600525
日期:2007.7.2
An efficient and selective synthesis of organiccarbonatesusingnanocrystallinemagnesiumoxide has been realized by the direct condensation of alcohols and diethyl carbonate. The catalyst is quantitatively recovered by simple centrifugation and can be reused for four cycles with almost consistent activity.
Dinitrogen oxide was employed as a clean oxidant for various oxidations in the presence of a catalytic amount of dioxoruthenium tetramesitylporphyrin complex (Ru(tmo)(O) 2 ). A variety of olefins, secondary alcohols, and benzyl alcohols were smoothly oxidized to the corresponding epoxides, ketones, and aldehydes in high yields. In the oxidation of 9,10-dihydroanthracene derivatives, the competitive
A Convenient Synthesis of 5,6β-Epoxides of Some Cholesteryl Esters and Δ<sup>5</sup>-Ketosteroid Derivatives by Catalytic β-Stereoselective Epoxidation
作者:Jean-Claude Marchon、René Ramasseul
DOI:10.1055/s-1989-27261
日期:——
The epoxidation of a series of cholesteryl esters by air in the presence of a catalytic amount of a ruthenium tetramesitylporphyrin complex is described. The preparative procedure, which requires only 4 to 5 mol % of the catalyst, leads to high conversion (76 to 94 %) and very high β-stereoselectivity (> 99 %). Similar results are obtained in the epoxidation of 3β-acetoxyandrost-5-ene-17-one, 3β-acetoxypregn-5-ene-20-one, and 3,3-ethylenedioxycholest-5-ene.
β-Selective Epoxidation of Cholesterol Derivatives with Molecular Oxygen and Aldehyde Catalyzed by Manganese(II) Complex
作者:Tohru Yamada、Kiyomi Imagawa、Teruaki Mukaiyama
DOI:10.1246/cl.1992.2109
日期:1992.11
In the presence of a catalytic amount of bis(dipivaloylmethanato)manganese(II) (= Mn(dpm)2), various cholesterol derivatives are smoothly converted into the corresponding β-epoxides in good to high yields with combined use of molecular oxygen and isobutyraldehyde. These stereoselectivities are the reversal of the cases using peracid such as mCPBA.
COMPOSITION AND METHOD FOR TEMPORARILY FIXING SOLID
申请人:JSR Corporation
公开号:EP1522567A1
公开(公告)日:2005-04-13
The present invention relates to a method of temporarily and firmly fixing two solids to each other and to a composition used in the method, which is a method of temporarily fixing, comprising temporarily fixing the two solids to each other with a liquid crystal compound or a composition comprising the liquid crystal compound. This method is used for a method of temporarily fixing a pad for chemical mechanical polishing, for example, to polish a wafer for a semiconductor device fixed on a surface of a base plate, when one solid is a pad for chemical mechanical polishing of a wafer for a semiconductor device and the other is a base plate to fix the pad.