SYNTHETIC DESIGN FOR CONSTRUCTION OF SOME RING SYSTEMS UTILIZING HETERO ATOMS

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(1)Ring-formation reaction for [m+n]-membered rings: mpi-components were designed by combination of a silyl enol ether with some conjugated groups. Thus, in the conjugated system with a pyrrole, indole derivatives were obtained by regioselective [4+2]cycloaddition reaction with acetylenic dienophiles. Furthermore, novel type of [4+3]cycloaddition reaction was developed in the conjugated system with a carnonyl group and its analogs; a seven-membered ring could be constructed via the oxyallyl cation intermediate. CF_3-substituted pyrroles were synthesized by means of [3+2]cycloaddition reaction.(2)Ring-derivatization on unique ring systems: For adamantane, the nitrone at its bridged position and the anti-Bredt type olefin at its bridgeheaded position were generated and studied on the addition reactivity. In the latter case, the compounds could be treated around at room temperature because it was substituted with phenyl and ester groups ; this way of stabilization due to an electronic reason is the first example. For squaric acid, carbon-carbon bond formation reaction was carried out under electrophilic conditions using an unsaturated organosilanes, and 1,2-vs 1,4-addition was found to occur depending on the nature of substituents, Lewis acid and reaction temperature. The adducts were further converted to butenolides. For C_<60>, enough addition reactivity of azo-compound as well as some 1,3-dipoles and dienophiles were confirmed in the preliminary works.