Lewis acid-promoted electron transfer deoxygenation of epoxides, sulfoxides, and amine N-oxides: the role of low-valent niobium complexes from NbCl5 and Zn
作者:Kyungsoo Oh、William Eric Knabe
DOI:10.1016/j.tet.2009.02.013
日期:2009.4
A mild and operationally simple deoxygenation of epoxides, sulfoxides, and amine N-oxides is described using a sub-stoichiometric amount of low-valent niobium complexes generated in situ from commercially available NbCl5 and zinc dust. The deoxygenation proceeds by a reductive cleavage of polarized O–C/O–N/O–S bonds through a single electron transfer from zinc metal to the niobium–substrate complex
Catalysis of Phosphorus(V)-Mediated Transformations: Dichlorination Reactions of Epoxides Under Appel Conditions
作者:Ross M. Denton、Xiaoping Tang、Adam Przeslak
DOI:10.1021/ol102010h
日期:2010.10.15
A stereospecific triphenylphosphine oxide-catalyzed 1,2-dichlorination reaction of epoxides has been developed. The reaction is effective for a range of terminal and internal epoxides. In contrast to the classical Appel-type dichlorination of epoxides, oxalyl chloride is used as a stoichiometric reagent to generate the chlorophosphonium salt responsible for dichlorination from catalytic triphenylphosphine
Regioselective Conversion of Unsymmetrical Terminal Epoxides into Vicinal Chlorohydrins Using Dimethoxyboron Chloride
作者:Chandra D. Roy
DOI:10.1071/ch06315
日期:——
synthesis of chlorohydrins by chlorinative cleavage of unsymmetrical epoxides utilizing dimethoxyboron chloride is described. Except for styrene oxide, all the terminal epoxides were regioselectively cleaved following a predominantly SN2-type reaction pathway favouring the formation of primary chlorides. In the case of styrene oxide, a benzylic epoxide, (MeO)2BCl transfers the chlorine at the benzylic
METHOD FOR SYNTHESIS OF HALOPYRIDYL-ACYCLOPENTANE DERIVATIVE AND INTERMEDIATE THEREOF
申请人:——
公开号:US20020010339A1
公开(公告)日:2002-01-24
The present invention relates to a method for synthesis of an optically active halopyridyl-azacyclo-pentane derivative and the intermediate thereof which comprises preparing an optically active allene-1,3-dicarboxylic acid ester derivative from an optically active acetonedicarboxylic acid ester derivative and then proceeding through a 7-azabicyclo[2.2.1]heptane derivative to obtain the objective product.
The present invention relates to a method for producing an alkali cellulose with suppressed decrease in the degree of polymerization as well as with small use amount of a basic compound, and to a method for producing a cellulose ether by using the alkali cellulose thus obtained. Provided by the present invention are: (A) a method for producing an alkali cellulose, comprising Step 1 wherein a cellulose-containing raw material is pulverized in the presence of 0.6 to 1.5 mol of a basic compound relative to 1 mol of an anhydroglucose unit that constitutes a cellulose in the said cellulose-containing raw material and under the condition in which the water content therein relative to the cellulose in the cellulose-containing raw material is 10% or less by mass thereby obtaining a cellulose powder mixture having the median diameter of the cellulose-containing raw material made 150 µm or less and Step 2 wherein water content therein is adjusted in the range of 30 to 100% by mass relative to the cellulose by adding water to the cellulose powder mixture thereby obtaining the alkali cellulose in the powder form; and (B) a method for producing a cellulose ether by reacting the alkali cellulose produced by the foregoing production method with an etherification agent.