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Sustainable Micellar Gold Catalysis – Poly(2‐oxazolines) as Versatile Amphiphiles
Author(s) -
Lempke Linda,
Ernst Andrea,
Kahl Fabian,
Weberskirch Ralf,
Krause Norbert
Publication year - 2016
Publication title -
advanced synthesis and catalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.541
H-Index - 155
eISSN - 1615-4169
pISSN - 1615-4150
DOI - 10.1002/adsc.201600139
Subject(s) - chemistry , amphiphile , cationic polymerization , aqueous solution , catalysis , polymer chemistry , polymerization , polymer , organic chemistry , micelle , bromide , copolymer
The application of five polymer amphiphiles in the gold‐catalyzed allene cycloisomerizations under aqueous micellar conditions is described. The polymers were prepared by ring‐opening cationic polymerization based on poly(2‐methyl‐2‐oxazoline) as hydrophilic segment and different hydrocarbon‐ or fluorocarbon‐based hydrophobic segments. The catalytic activity in the gold‐catalyzed allene cyclization is strongly dependent on the type of gold precursor, the salt concentration in the bulk aqueous medium, and the concentration of the polymeric amphiphile. Best results were obtained with 2 mol% of gold(III) bromide, 1 mM of amphiphile and 5 M sodium chloride, affording over 80% yield for different heterocyclic products. The catalyst system is also suitable for the dehydrative cyclization of acetylenic diols to furans. Moreover, successful catalyst recycling was demonstrated in three consecutive runs when using optimized extraction conditions.