(Hive Bee)
11-23-03 19:13
No 472765
(Rated as: good read)
Solvent -Free Accelerated Organic Syntheses using Microwaves
Pure Appl.Chem. vol.73, No.1,pp.193-198 (2001)
http://www.iupac.org/publications/pac/20
Abstract.A solvent-free approach for organic synthesis is described which involves microwave (MW) exposure of neat reactants (undiluted) either in the presence of a catalyst or catalyzed by the surfaces of inexpensive and recyclable mineral supports such as alumina, silica, clay, or "doped" surfaces, namely, Fe(NO3)3-clay (clayfen), Cu(NO3)2-clay (claycop), NH2OH-clay, PhI(OAc)2-alumina, NaIO4-silica, MnO2-silica, and NaBH4-clay. A variety of deprotection, condensation, cyclization, oxidation, and reduction reactions are presented including the efficient one-pot assembly of heterocyclic molecules from in situ generated intermediates such as enamines and a-tosyloxyketones. The application of this solvent-free MW approach to multicomponent reactions is highlighted that can be adapted for high-speed parallel synthesis of the library of dihydropyrimidine-2(1H)-ones and imidazo [1,2-a]annulated pyridines, pyrazines, and pyrimidines.
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