Phase-transfer catalysis macrocycle synthesis

Phase-transfer catalysis can be used to mimic high dilution reaction conditions and has been utilized to good effect in the synthesis of large ring lactones [67J. Macrocyclic nitrolactones have also been obtained by rearrangement of 2-(3-hydroxy-propyI)-2-nitrocycloalkanones using a stoichiometric amount of tetra-n-butyl-ammonium fluoride [68]. 

The publication of Pedersen s work attracted instant and increasing attention from a variety of scientists worldwide. During the ensuing decade, research in an increasing number of laboratories led to the synthesis and characterization of many novel macrocychc chemical structures, and to the application of macrocycles in a wide variety of fields. This effort cut across many areas including organic and inorganic synthesis, biochemistry, ion transport in membranes, phase transfer catalysis, and structure analysis. 

Another application of copolymerization technology is the synthesis of resins containing crown ether units to give materials with extraction and re-extraction properties. These resins are synthesized from phenol or 1,3-benzenediol, methanal, and benzo-13-crown-4 and benzo-9-crown-3 (Scheme 24). These crown ether containing resins show otential applications in catalysis because of easy recovery of the resin beads by filtration and the prevention of contamination of the catalyzed product with toxic macrocycles. Furthermore, these modified phenolics may be applicable in analytic chemistry as chromatographic stationary phases for separation of ionic substances from neutral ones and in heterogeneous phase-transfer catalysis in preparative chemistry [162],... 

Polymer-supported crown ethers and cryptands were found to catalyze liquid-liquid phase transfer reactions in 1976 55). Several reports have been published on the synthesis and catalytic activity of polymer-supported multidentate macrocycles. However, few studies on mechanisms of catalysis by polymer-supported macrocycles have been carried out, and all of the experimental parameters that affect catalytic activity under triphase conditions are not known at this time. Polymer-supported macrocycle... 

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