Study On The Diastereoselectivity Diels-Alder Reaction And Biginelli-type Condensation Reaction Catalyzed By Lanthanide Halides

The lanthanide halides catalyzed syntheses of several kinds of azaheterocycle arestudied in this thesis, which is composed with three parts as follows:1. Samarium diiodid is found to be an efficient catalyst in the three-component iminoDiels-Alder reaction of aromatic aldehyde, aromatic amine with dihydropyran ordihydrofuran to afford pyrano[3,2-c]-or furano[3,2-c]quinoline in good yields with highstereoselectivity. Either of the cis and trans isomers can be obtained as the major productby changing the reaction conditions conveniently. Higher temperature and lower substrateconcentration give more the thermodynamic stable trans products, and lower temperatureand higher substrate concentration lead to a fast formation of the kinetically favored cisproducts.2. The Biginelli-type condensation of aromatic aldehyde, urea or thiourea withcyclopentanone is effectively catalyzed by hydrated ytterbium chloride (YbCl₃·nH₂O)affording benzylidene hctcrobicyclic pyrimidine-2-one in moderate to excellent yields. Thereaction can proceed smoothly in the absence of solvent in the atmosphere withoutrigorous exclusion of oxygen and moisture.In addition, the nitro-Mannich reaction of nitroethane with sulfonylimine catalyzed byYb(OⁱPr)₃-cinchonine is explored.