Conotoxin analogues and methods for synthesis of intramolecular dicarba bridge-containing peptides
申请人:Robinson Andrea
公开号:US20070197429A1
公开(公告)日:2007-08-23
According to the present invention, there is provided a range of new conotoxin derivatives and methods for synthesizing these analogues and other intramolecular dicarba bridge-containing peptides, including dicarba-disulfide bridge-containing peptides.
A Self‐Assembled Cage with Endohedral Acid Groups both Catalyzes Substitution Reactions and Controls Their Molecularity
作者:Paul M. Bogie、Lauren R. Holloway、Courtney Ngai、Tabitha F. Miller、Divine K. Grewal、Richard J. Hooley
DOI:10.1002/chem.201902049
日期:2019.8
magnitude weaker. Most importantly, the cage host alters the molecularity of the reaction: whereas the reaction catalyzed by simple acids is a unimolecular, SN1‐type substitution process, the rate of the host‐mediated process is dependent on the concentration of nucleophile. The molecularity of the cage‐catalyzed reaction is substrate‐dependent, and can be up to bimolecular. In addition, the catalysis
内部具有酸功能的自组装Fe 4 L 6笼状复合物能够将活化的醇,醚和胺的硫醚化速度提高多达1000倍。看不到任何产物抑制作用,只有低至5%的笼数,才能发生有效的超分子催化。底物以高达微摩尔的亲和力结合在宿主中,而产物显示的结合力弱了一个数量级。最重要的是,笼型宿主会改变反应的分子:而由简单酸催化的反应是单分子的S N1型替代过程中,宿主介导过程的速率取决于亲核试剂的浓度。笼催化反应的分子是取决于底物的,并且可以高达双分子。另外,可以通过大量过量的亲核试剂来防止催化作用,其中底物抑制起主要作用,并且使用三苯甲基化的苯胺作为底物会产生负反馈回路,由此释放出的产物会破坏催化剂并停止反应。
Catalyst component for the polymerisation of olefins and process for preparing olefin polymers using same
申请人:NIPPON OIL COMPANY, LIMITED
公开号:EP0587440A2
公开(公告)日:1994-03-16
A catalyst component for use in the polymerization or copolymerization of olefin(s) is obtained by contacting the following components (1) to (4) with one another:
(1) a compound of the general formula Me¹R¹p(OR²)qX¹4-p-q where R¹ is a hydrocarbon radical having 1 to 24 carbon atoms, X¹ is a halogen atom, Me¹ is Zr, Ti or Hf, and n is 0 ≦ n ≦ 4;
(2) a compound of the general formula Me²R³m(OR⁴)nX²z-m-n where R² is a hydrocarbon radical having 1 to 24 carbon atoms, X² is a halogen atom, Me² is an element from Groups I to III in the Periodic Table, z is the valence of Me² and m is 0 ≦ m ≦ z;
(3) an organocyclic compound having two or more conjugated double bonds; and
(4) a modified organoaluminum compound containing Al-O-Al bond and with at least one branched-chain alkyl group being attached to aluminum atom.
A study was made of the isomerization reaction of a great variety of trimethyl alpha-keto trithioorthocarboxylates to alpha,alpha-bis(methylthio) thiolcarboxylates, intermediates of high synthetic value for the synthesis of alpha-arylpropionic acids. The reaction was carried out In methylene chloride in the presence of catalytic amounts of trityl perchlorate or methanesulfonic acid and was complete in 2 h at rt. In most of the investigated cases the result was positive, the yields usually being greater than 90%. Also the reaction mechanism was subjected to an experimental study.