Solvent-free accelerated organic syntheses using microwaves

A solvent-free approach for organic synthesis is described which involves m icrowave (MW) exposure of neat reactants (undiluted) either in the presence of a catalyst or catalyzed by the surfaces of inexpensive and recyclable m ineral 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 deprote ction, condensation, cyclization, oxidation, and reduction reactions are pr esented including the efficient one-pot assembly of heterocyclic molecules from in situ generated intermediates such as enamines and alpha -tosyloxyke tones. The application of this solvent-free MW approach ro multicomponent r eactions is highlighted that can be adapted for high-speed parallel synthes is of the library of dihydropyrimidine-2(1H)-ones and imidazo [1,2-a]annula ted pyridines, pyrazines, and pyrimidines.