Synergistic dual activation catalysis by palladium nanoparticles for epoxide ring opening with phenols
作者:Kapileswar Seth、Sudipta Raha Roy、Bhavin V. Pipaliya、Asit K. Chakraborti
DOI:10.1039/c3cc42507j
日期:——
Synergistic dual activation catalysis has been devised for epoxide phenolysis wherein palladium nanoparticles induce electrophilic activation via coordination with the epoxide oxygen followed by nucleophilic activation through anion-pi interaction with the aromatic ring of the phenol, and water (reaction medium) also renders assistance through 'epoxide-phenol' dual activation.
Bi(OTf)<sub>3</sub>-catalyzed Regioselective Ring Opening of Epoxides with Phenols: Facile Synthesis of 1,3-Diaryloxy-2-propanols
作者:Ahmed Kamal、Syed Kaleem Ahmed、Mahendra Sandbhor、Mohammed Naseer Ahmed Khan、Mohammed Arifuddin
DOI:10.1246/cl.2005.1142
日期:2005.8
Substituted aryl oxiranes undergo the facileringopening with phenols in the presence of catalytic amount of bismuth(III) triflate to afford 1,3-diaryloxy-2-propanols in excellent yields under mild conditions. Bismuth(lll) triflate is relatively nontoxic, easy to handle and inexpensive, which makes this procedure particularly attractive for large scale synthesis.
Silver nanoparticle-catalysed phenolysis of epoxides under neutral conditions: Scope and limitations of metal nanoparticles and applications towards drug synthesis
作者:Kapileswar Seth、Sudipta Raha Roy、Damodara N. Kommi、Bhavin V. Pipaliya、Asit K. Chakraborti
DOI:10.1016/j.molcata.2014.05.011
日期:2014.10
Chemo- and regio-selective epoxide phenolysis is reported for the first time under neutral condition catalysed by silver nanoparticles. Other metal nanoparticles (e.g., Au, Pd, Cu, In, and Ru) are less effective. The choice of solvent is critical with 2-propanol being the best followed by DEF. Amongst various stabilisers used (surfactants, PEGs, tetra-allcylammonium halides) the tetra-alkylammonium halides are found to be the most effective (TBAF > TBAB > TBACl > TBAI). The role of the silver nanoparticles is envisaged as synchronous mode epoxide-phenol dual activation via a cooperative network of coordination, anion-it interaction, and hydrogen bond. The silver nanoparticles are recovered and reused for five consecutive times. The reaction has been used for the synthesis of propranolol and naftopidil as a few representative cardiovascular drugs. (C) 2014 Published by Elsevier B.V.
Synthesis, characterization and catalytic activity of novel large network polystyrene-immobilized organic bases
In view of searching for efficient solid catalysts to be used in environmentally friendly reaction conditions, novel gel-type cross-linked polystyrenes functionalized with diethylamine and 1,5,7-triazabicyclo[4.4.0]dec-5-ene, have been prepared.