[EN] PROCESS FOR THE CATALYTIC DIRECTED CLEAVAGE OF AMIDE-CONTAINING COMPOUNDS<br/>[FR] PROCÉDÉ POUR LE CLIVAGE CATALYTIQUE DIRIGÉ DE COMPOSÉS CONTENANT UN AMIDE
申请人:UNIV ANTWERPEN
公开号:WO2017046133A1
公开(公告)日:2017-03-23
The present invention relates to a catalytic method for the conversion of amide-containing compouds by means of a build-in directing group and upon the action of a heteronucleophilic compound (in se an amine (RNH2 or RNHR') or an alcohol (ROH) or a thiol (RSH)) in the presence of a metal catalyst to respectively esters, thioesters, carbonates, thiocarbonates and to what is defined as amide-containing compounds (such as carboxamides, urea, carbamates, thiocarbamates). The present invention also relates to these amide-containing compounds having a build-in directing group (DG), as well as the use of such directing groups in the catalytic directed cleavage of N-DG amides with the use of heteronucleophiles (in se an amine (RNH2 or RNHR') or an alcohol (ROH) or thiol (RSH)).
[EN] HALOGENATED CHOLESTEROL ANALOGUES AND METHODS OF MAKING AND USING SAME<br/>[FR] ANALOGUES HALOGÉNÉS DU CHOLESTÉROL ET LEURS PROCÉDÉS DE PRÉPARATION ET LEURS MÉTHODES D'UTILISATION
申请人:UNIV MICHIGAN REGENTS
公开号:WO2020069267A1
公开(公告)日:2020-04-02
Provided herein are halogenated cholesterol analogues, including methods of making and using the same. Also provided are methods of making radiolabeled cholesterol analogues including admixing an epoxide with a fluorine-18 source under conditions to form a radiofluorinated cholesterol analogue.
Zn-Catalyzed<i>tert</i>-Butyl Nicotinate-Directed Amide Cleavage as a Biomimic of Metallo-Exopeptidase Activity
作者:Clarence C. D. Wybon、Carl Mensch、Charlie Hollanders、Charlène Gadais、Wouter A. Herrebout、Steven Ballet、Bert U. W. Maes
DOI:10.1021/acscatal.7b02599
日期:2018.1.5
A two-step catalytic amide-to-ester transformation of primary amides under mild reaction conditions has been developed. A tert-butyl nicotinate (tBu nic) directing group is easily introduced onto primary amides viaPd-catalyzed amidation with tert-butyl 2-chloronicotinate. A weak base (Cs2CO3 or K2CO3) at 40–50 °C can be used provided that 1,1′-bis(dicyclohexylphosphino)ferrocene is selected as ligand
已经开发了在温和的反应条件下伯酰胺的两步催化酰胺转化为酯的方法。甲叔丁基烟酸甲酯(吨卜NIC)指示组很容易通过Pd催化的酰胺化与引入到伯酰胺叔丁基2-氯烟。如果选择1,1'-双(二环己基膦基)二茂铁作为配体,则可以使用40–50°C的弱碱(Cs 2 CO 3或K 2 CO 3)。所述吨卜NIC活化酰胺随后允许的Zn(OAc)2催化的醇解nonsolvolytic在吨在中性反应条件下于40–60°C的BuOAc。激活机制是仿生的:在引导基团中吡啶的C3酯取代基构成了适合Zn螯合的反式构象异构体,C═O酰胺-Zn-N引导基团,并且Zn配位醇还被激活为亲核试剂通过氢键与催化剂的乙酸酯配体键合。另外,乙酸盐配体有助于分子内O至N质子转移。化学选择性相对于其他官能团以及与具有挑战性的反应伙伴(如肽,糖和固醇)的相容性说明了这种两步酰胺裂解方法的合成适用性。该Ť卜NIC酰胺在裂解前不需要纯化。初步实验
Synthesis of 5α-Cholestane Type Glycoside Sulfates
Synthesis of steroid glycoside sulfates sulfated both on the steroid skeleton and in sugar part are presented. Sodium salts of 5α-cholestane-3β,6α-diol 6-β-D-glucoside 3-sulfate V and 3-β-D-glucoside 6-sulfate XI were prepared from 3β-(2-tetrahydropyranyloxy)-5α-cholestan-6α-ol (I) using acetyl and methoxymethyl groups for temporary protection. Sulfation in the sugar part was at first checked in pregnane series and triethylammonium salts of 3β-(β-D-glucopyranosyloxy)pregn-5-en-20-one 6'-sulfate (XXVI) and 4'-sulfate 2',3'-diacetate XXVII were prepared. Application of the method on cholestane derivatives gave triethylammonium salt of 5α-cholestan-3β-yl β-D-glucopyranoside-6-sulfate (XXXI).
A Highly β-Stereoselective Catalytic Epoxidation of Δ<sup>5</sup>-Unsaturated Steroids with a Novel Ruthenium(II) Complex under Aerobic Conditions
作者:Venkitasamy Kesavan、Srinivasan Chandrasekaran
DOI:10.1021/jo980829k
日期:1998.10.1
6alpha-epoxides as the major products. The overall conformation of the steroid nucleus is nearly planar in the cholesteryl ester, while it is bent at the junction between the rings A and B in the 5beta,6beta-epoxide. This change from pseudo-trans- to cis-stereochemistry of the A-B ring junction provides more room for the catalyst to approach from the beta-face of the steroidal skeleton.