Abstract
This thesis describes the synthesis and a detailed study on the photorearrangements of several heteroarene-fused barrelenes.A series of pyrazinobarrelenes (1, 1*, 4, 6, 8), quinoxalinobarrelenes (2, 2*, 5, 7, 9) and benzoquinoxalinobarrelenes (3, 10) were prepared in good to excellent yields (45 - 98% yields) from the condensation of bicyclo[2.2.2]octa-5,7-diene-2,3-diones (15, 15*, 20, 25, 29) with 1,2-diamino-1,2-dicyanoethylene (diaminomaleonitrile), 1,2-diamiobenzene, 2,3-diaminonaphthalene.These heteroarene-fused barrelenes underwent two kinds of rearrangement reactions namely, di-□-methane (DPM) or aza-di-□-methane (ADPM) rearrangement upon direct irradiation with UV light or under sensitized condition. Reaction pathway depends upon several factors including the nature of the heteroarrene moiety, substituents (methyl group, n-propyl group) on the bridge-head and substituents (methoxy carbonyl group) on the double bond of the barrelenes. Triplet state energy of bridging moiety can be used in explanation of the reaction mode.Solvent effect on the mode of the reaction were also studied but gave no profound effect on the reaction pathway selectivities.The structures of all the new compounds were determined mainly by 1H NMR, 13C NMR and HRMS spectroscopic methods.