SYNTHESIS AND STRUCTURE OF NOVEL HETEROCYCLIC AMINOTELLURANES

A series of novel nzoxatellurazino[2,3-b]-[1,2,3]benzoxatellurazines 3 was synthesized from tetraalkoxytelluranes and bis(2-hydroxybenzyl)am ines. H-1, C-13 and Te-125 NMR studies suggest that these aminotellura nes, unlike their orthoamidoester analogs, have a rigid trans-fused co nformation. A preferential tr ans-fused conformation was also deduced from ab initio MO calculations of a model oxatellurazinooxatellurazine 7, using the STO-3G and SBK basis sets, and the Gaussian-92 program, which imply that the trans-fused aminotellurane is more stable than th e corresponding cia isomer by 10.3 kcal/mol. (C) 1997 Elsevier Science Ltd.