1-Alkoxycarbonylalkylidenetriphenylarsoranes: Preparation and reactions
摘要:
The higher homologues of the well-studied alkoxycarbonylmethylenetriphenylarsonium(1) ylide (3, R=H) can be easily obtained through the sequence: a). preparation of alkyl 2-trifloxyalkanoates (1); b), reaction between these trifloxyderivatives and triphenylphosphine to give 1-alkoxycarbonylalkyltriphenylarsonium triflates (2); and c), basic treatment of the triphenylarsonium triflates (2) with alumina-supported potassium fluoride to give 1-alkoxycarbonylalkyledenetriphenylarsonium ylides (3). These higher homologues of(3, R=H) react with aromatic aldehydes in good to excellent yields. and give rise to synthetically interesting ''coupling'' and cyclopropanation reactions.
A stereoselective synthesis of substituted maleic esters by use of phosphonates
作者:R. K. Huff、C. E. Moppett、J. K. Sutherland
DOI:10.1039/j39680002725
日期:——
The condensation of α-keto-esters with the anions of α-phosphonato-esters yields mainly substituted maleic esters and little or none of the corresponding fumarates.
Reactions of carbethoxyalkylidenetriphenylphosphoranes with aryl azides
作者:P. Ykman、G. L'abbé、G. Smets
DOI:10.1016/s0040-4020(01)99395-0
日期:——
The title reaction has been shown to give a complex mixture of products from which triazoles (12 and 17), maleates (13), fumarates (14), triphenylphosphine oxide (15), iminophosphoranes (16) and triazenes (18) have been isolated. Their formation is rationalized by two reaction paths, involving addition of the azide onto the CC and CP bonds of the ylide. Diazoesters 5 and 19, which should result from
Components and catalysts for the polymerization of olefins
申请人:——
公开号:US20040014595A1
公开(公告)日:2004-01-22
The present invention relates to a solid catalyst component for the polymerization of olefins CH
2
═CHR in which R is hydrogen or a hydrocarbon radical with 1-12 carbon atoms, comprising Mg, Ti, halogen and an electron donor selected from maleates of a particular formula. Said catalyst components when used in the polymerization of olefins, and in particular of propylene, are capable to give polymers in high yields and with high isotactic index expressed in terms of high xylene insolubility.