71872-03-2Relevant articles and documents
Rare-Earth-Metal-Complex-Catalyzed Hydroalkoxylation and Tandem Hydroalkoxylation/Cyclohydroamination of Isocyanates: Synthesis of Carbamates and Oxazolidinones
Zhu, Xiancui,Qi, Yawen,Yang, Yuanqing,Guo, Dianjun,Huang, Zeming,Zhang, Lijun,Wei, Yun,Zhou, Shuangliu,Wang, Shaowu
, p. 3202 - 3211 (2022/02/23)
Novel N,N,N-tridentate β-diketiminato rare-earth-metal dialkyl complexes LRE(CH2SiMe3)2 [RE = Y (1a), Gd (1b), Yb (1c), Lu (1d); L = MeC(NDipp)CHC(Me)N(CH2)2NC4H8, where Dipp = 2,6-iPr2C6H3] have been conveniently synthesized by one step from reactions of the rare-earth-metal trialkyl complexes RE(CH2SiMe3)3(THF)2 (THF = tetrahydrofuran) with a pyrrolidine-functionalized β-diketiminate HL, and their catalytic behaviors toward hydroalkoxylation and tandem hydroalkoxylation/cyclohydroamination of isocyanates have been described. These rare-earth-metal catalysts exhibited high efficiency in the hydroalkoxylation of isocyanates, providing a variety of N-alkyl and N-aryl carbamate derivatives under mild reaction conditions with a rather low catalyst loading (0.04 mol %). More significantly, they can promote a tandem hydroalkoxylation/cyclohydroamination reaction between terminal and internal propargylic alcohols with substituted arylisocyanates, leading to the efficient synthesis of methylene and (Z)-selective arylidene oxazolidinones in good-to-high yields via consecutive C-O and C-N bond formation. The stoichiometric reaction of 1a with p-tolylisocyanate generated an unusual dinuclear yttrium complex, {[η2-(4-MePhNCO)(CH2SiMe3)]Y[μ-η2:η1:η1-(4-MePhNCO)CC(Me)(NDipp)C(Me)N(CH2)2NC4H8]}2 (7a), with two different amidate units, which underwent an sp2 C-H bond activation of the β-diketiminato backbone, followed by the insertion of isocyanate.
Solvent free N-Boc protection of amines using amberlystr a 21 solid base resin as a reusable heterogeneous catalyst
Tekale, Sunil U.,Kauthale, Sushama S.,Pawar, Rajendra P.
, p. 1619 - 1623 (2013/09/12)
An efficient, environmentally benign, highly facile and convenient synthetic protocol for the selective t-butyl carboxylation of aliphatic, aromatic and heterocyclic amines using AmberlystR A 21 catalyst; a mild basic solid resin under solvent free conditions is reported. This method explores several advantages such as reusability of the heterogeneous catalyst, cleaner reaction profile, mild and solvent free system, short reaction time, operational simplicity, high conversions , excellent product yields and low cost of the catalyst. Furthermore since the catalyst is mild basic, decomposition of the carbamate formed is not observed if the reaction is continued for prolonged time as in the case of Lewis acid catalyzed N-Boc protection. This makes the present protocol a useful and attractive for N-Boc protection of amines.
Magnetic nanoparticles catalyzed N-tert-butoxycarbonylation of Amines and amine derivatives
Akbari, Jafar,Sajirani, Soghra B.,Nezhad, Jafar M.,Heydari, Akbar
experimental part, p. 165 - 168 (2012/07/14)
A simple and efficient protocol for the chemoselective mono-N-Boc protection of various structurally diverse amines with di-tert-butyl dicarbonate using magnetically recoverable γ-Fe2O3@SiO 2 nanoparticles is reported. The catalyst can be easily recovered and recycled without a significant loss in the catalytic activity. No competitive side reactions, such as formation of isocyanate, urea, oxazolidinone, and N,N-di-Boc derivatives were obsereved.
