[4 + 2] Cycloaddition Reactions Catalyzed by a Chiral Oxazaborolidinium Cation. Reaction Rates and Diastereo-, Regio-, and Enantioselectivity Depend on Whether Both Bonds Are Formed Simultaneously
摘要:
The reaction rates and products in enantioselective Diels-Alder reactions with a range of dienophiles correlate with the expected degree of concertedness of bond formation in the transition state.
[4 + 2] Cycloaddition Reactions Catalyzed by a Chiral Oxazaborolidinium Cation. Reaction Rates and Diastereo-, Regio-, and Enantioselectivity Depend on Whether Both Bonds Are Formed Simultaneously
摘要:
The reaction rates and products in enantioselective Diels-Alder reactions with a range of dienophiles correlate with the expected degree of concertedness of bond formation in the transition state.
Use of adsorbent polymer particles in DNA separation
申请人:——
公开号:US20030162853A1
公开(公告)日:2003-08-28
The invention is directed to fluorinated particles having adsorbent properties for superior performance as the stationary phase for use in chromatographic separations. In particular, the fluorinated surface of such particles of the invention presents unusual and unexpected polarity that is beneficial in performing chromatographic separations such as that used for DNA.
A latently-curable, organosilicone composition comprises a metal catalyzed organosilicone composition capable of undergoing hydrosilation and, as hydrosilation inhibitor, an organic monohydrogen derivative of an unsaturated aliphatic 1,4-dicarboxylic acid, i.e., maleic acid or acetylene dicarboxylic acid. The organic monohydrogen derivatives of use in this invention effectively inhibit catalyzed hydrosilation reactions at low or room temperature while allowing efficient hydrosilation reaction rates to occur at elevated temperatures. These monohydrogen derivatives perform their inhibitive function effectively at low concentration. The latently curable composition may be coated on a substrate to provide a release surface for an adjacent adhesive layer.