1,1,1,3,3,3-Hexafluoroisopropanol: A Recyclable Organocatalyst for<i>N</i>-Boc Protection of Amines
作者:Akbar Heydari、Samad Khaksar、Mahmood Tajbakhsh
DOI:10.1055/s-2008-1067272
日期:2008.10
A simple and efficient protocol for the chemoselective mono-N-Boc protection of various structurally diverse amines with di-tert-butyl dicarbonate using 1,1,1,3,3,3-hexafluoroisopropanol (HFIP) as solvent and catalyst is described. The catalyst can be readily separated from the reaction products and recovered for direct reuse. No competitive side reactions such as formation of isocyanate, urea, and N,N-di-Boc were observed. α-Amino alcohols afforded the N-Boc derivatives without oxazolidinone formation.
Résumé An efficient and practical protocol for the chemoselective N-Boc protection of various structurally different aryl, aliphatic and heterocyclic amines was carried out with (Boc)2O using protic 1, 1, 3, 3-tetra-methylguanidinium acetate (10 mol%) as recyclable catalyst under solvent free condition at ambient temperature. No competitive side reactions (isocyanate, urea and N, N-di-Boc) were observed. α-Amino alcohols afforded the N-Boc-derivative without oxazolidinone formation.
{[[K.18-Crown-6]Br3}n: A tribromide catalyst for the catalytic protection of amines and alcohols
作者:Gholamabbas Chehardoli、Mohammad Ali Zolfigol、Fateme Derakhshanpanah
DOI:10.1016/s1872-2067(12)60644-5
日期:2013.9
[K.18-Crown-6]Br3}n, a unique tribromide-type catalyst, was utilized for the N-boc protection of amines and trimethylsilylation (TMS) and tetrahydropyranylation (THP) of alcohols. The method is general for the preparation of N-boc derivatives of aliphatic (acyclic and cyclic) and aromatic, and primary and secondary amines and also various TMS-ethers and THP-ethers. The simple separation of the catalyst
An efficient ZnO nano catalyst, which was readily prepared from Zn(CH3CO2)2, 2H2O and PVP by a chemical solution approach has successfully catalyzed N-tertbutoxy carbonylation of amines. The ZnO nanorods were successful and gave promising results for highly active and chemoselective as well as easily recyclable catalyst for the NBoc protection reaction of a wide variety of amines. The catalyst could be easily recycled for five times without noticeable decrease in catalytic activity. The ZnO nanocatalyst was characterized with XRD and SEM.
heteropoly acid H3PW12O40 (0.5 mol %) is a very efficient and environmentally benign catalyst for N-tert-butoxycarbonylation of amines (primary, secondary) with di-tert-butyl dicarbonate at room temperature in short reaction times (<10 min). No competitive side products such as isocyanates, ureas, N,N-di-tert-butoxycarbonyls, O-Boc and oxazolidinones were observed. Chiral α-amino alcohols and esters
市售的杂多酸H 3 PW 12 O 40(0.5 mol%)是一种非常有效且对环境无害的催化剂,用于在室温下短时间反应中用二碳酸二叔丁酯将胺(伯,仲)的N-叔丁氧羰基化次(<10分钟)。没有竞争的副产物如异氰酸酯,脲,Ñ,ñ -二-叔-butoxycarbonyls,ö -Boc和恶唑烷酮观察。手性α-氨基醇和酯以优异的产率化学选择性地提供了相应的N- Boc衍生物。