Enantioselective Rhodium-Catalyzed [2 + 2 + 2] Cycloadditions of Terminal Alkynes and Alkenyl Isocyanates: Mechanistic Insights Lead to a Unified Model that Rationalizes Product Selectivity
作者:Derek M. Dalton、Kevin M. Oberg、Robert T. Yu、Ernest E. Lee、Stéphane Perreault、Mark Emil Oinen、Melissa L. Pease、Guillaume Malik、Tomislav Rovis
DOI:10.1021/ja905065j
日期:2009.11.4
describes the development and scope of the asymmetric rhodium-catalyzed [2 + 2 + 2] cycloaddition of terminal alkynes and alkenyl isocyanates leading to the formation of indolizidine and quinolizidine scaffolds. The use of phosphoramidite ligands proved crucial for avoiding competitive terminal alkyne dimerization. Both aliphatic and aromatic terminal alkynes participate well, with product selectivity a function
Asymmetric Synthesis of Bicyclic Amidines via Rhodium-Catalyzed [2+2+2] Cycloaddition of Carbodiimides
作者:Robert T. Yu、Tomislav Rovis
DOI:10.1021/ja710065h
日期:2008.3.1
A highly enantioselective rhodium-catalyzed [2+2+2] cycloaddition of terminal alkynes and alkenyl carbodiimides has been developed. This reaction demonstrates the feasibility of olefin insertion into carbodiimide-derived metalacycles and provides a new class of chiral bicyclic amidines as the major products. An isonitrile migration process responsible for the formation of the minor cycloadduct can
Rhodium-Catalyzed [2 + 2 + 2] Cycloaddition of Alkenyl Isocyanates and Alkynes
作者:Robert T. Yu、Tomislav Rovis
DOI:10.1021/ja057803c
日期:2006.3.1
rhodium(I)-catalyzed [2 + 2 + 2] cycloaddition between alkenyl isocyanates and alkynes has been developed. Heating a mixture of an alkenyl isocyanate and a symmetrical internal alkyne in the presence of [Rh(ethylene)2Cl]2/P(4-OMe-C6H4)3 in toluene delivers substituted indolizinones and quinolizinones. Depending on the substrates, a rare fragmentation of the isocyanate unit can be involved within the cycloaddition process
PROCESS FOR PRODUCING VINYL POLYMER HAVING ALKENYL GROUP AT END, VINYL POLYMER, AND CURABLE COMPOSITION
申请人:KANEKA CORPORATION
公开号:EP1375531A1
公开(公告)日:2004-01-02
Objects of the present invention are to provide a process for easily producing an alkenyl-terminated vinyl polymer without using a metal compound requiring a complicated purification step, and to provide a curable composition containing the vinyl polymer.
An alkenyl group is incorporated into an end of a vinyl polymer having a thiocarbonylthio structure at the end to produce an alkenyl-terminated vinyl polymer. Mixing this vinyl polymer with a compound having a hydrogen-silicon bond and a hydrosilylation catalyst gives the curable composition.
The present invention provides a curable composition that comprises a polymer (A) containing a cross-linkable silyl group and a condensation catalyst (B). The polymer (A) containing a cross-linkable silyl group is obtained by a process comprising the steps of conducting a radical polymerizable monomer in the presence of a thiocarbonylthio compound. For example, the polymer (A) is obtained by (i) initiating a reversible addition-fragmentation chain transfer polymerization of a radical polymerizable monomer in the presence of a thiocarbonylthio compound, and (ii) adding an unsaturated compound containing a cross-linkable silyl group for copolymerization when a consumed amount of the radical polymerizable monomer by the polymerization has reached a level of 80% or more.