Preparation Of Polystyrene-Supported 2-Seleno-3-amino-ester And Their Applications In The Synthesis Of Heterocyclic Compounds

In this dissertation, the preparation of polystyrene-supportedα-seleno-β-amino-ester and their applications in the synthesis of libraries with heterocyclic compounds were investigated.Firstly, a new strategy for the synthesis of 1,3-disubstituted uracils has been developed. The 1,3-disubstituted uracils were synthesized with good yields by amino-selenenylation ofα,β-unsaturated esters and cyclization with isocyanates followed by oxidation-elimination of phenylseleno group. Furthermore, polystyrene-supportedα-seleno-β-amino-ester was prepared from 1% cross-linked polystyrene resin. Finally, 1,3,6-trisubstituted uracils were synthsized from polystyrene-supportedα-seleno-β-amino-ester through solid-phase amino-selenenylation ofα,β-unsaturated esters and cyclization with isocyanates followed by oxidative clevage.Secondly, nucleoside analogues containing uracils and another heterocyclic moiety have attracted much interest by virtue of their biological action as antiviral and anticancer agents. The intermediate resin-bound N1/N3-allyl/propargyl 5, 6-dihydrouracils were prepared. Then nucleoside analogues containing uracils and isoxazolines/isoxazoles were synthesized through 1,3-dipolar cycloaddition reaction between terminal ethylene or acetylene moiety and nitrile oxides and oxidative clevage. Furthermore, nucleoside analogues containing uracils and triazoles were synthesized through 1,3-dipolar cycloaddition reaction between terminal acetylene moiety and azides and oxidative cleavage. This strategy opens the way for the generation of small libraries of heterocyclic nucleoside analogues.Thirdly, the resin-bound 3-propargylamino-2-seleno-ester was prepared from polystyrene-supported selenium resin. Then the 3-amino-2-seleno-ester moiety was transformed to uracil or diazepinedione through condensation with isocyanate orα-amino-acid and oxidative cleavage and the terminal acetylene moiety is transformed to benzofuran or indole through a Sonogashira-annulation reaction with 2-iodophenol or 2-iodoaniline. This strategy opens the way for the generation of small libraries of heterocycles system consisting of uracil/diazepinedione and benzofuran/indole.Fourthly, the resin-bound 3-(2-aminophenylamino)-2-seleno-ester was prepared from polystyrene-supported selenium resin. Then pyrimido[1,2-a]benzimidazol-2(1H)-ones were synthesized through condensation between the resin-bound 3-(2-aminophenylamino)-2-seleno-ester and isothiocyanates followed by oxidative cleavage. Furthermore, 1,2-dihydro-3H-[1,4]diazepino[1,2-a]benzimidazol-3-ones were synthesized through condensation between the resin-bound 3-(2-aminophenylamino)-2-seleno-ester andα-amino-acids followed by oxidative cleavage.