| Abstract: | We have found that the thermolysis of 5-substituted-2-acyl-tetrazoles (I) at 60–110° leads to quantitative loss of nitrogen and formation of an N-acyl-nitrilimine (III) as a hypothetical intermediate. This immediately reacts via ring closure to form 1,3,4-oxadiazoles (IV) in excellent yields. By an elegant reaction series it is possible to form polyaryles with alternating phenyl and 1,3,4-oxadiazole rings by repeated reaction of 5-phenyltetrazole with p-cyano-benzoylchloride followed by treatment with lithium azide. Starting with terephthalonitrile polyaryles possessing 9 rings were synthesized in 4 steps. The ultra-violet absorption of the 2,5-disubstituted 1,3,4-oxadiazole systems resembles very closely the absorption curve of a p-disubstituted phenyl-group. |
