Flow vacuum pyrolysis of tetrazoles with annelated dibenzocycloalkane skeletons

Three new dibenzoannelated tetrazoloazocines 1-3 were synthesized from the corresponding ketones 6-8 and in situ generated triazidochlorosilane. The n ew compounds were characterized by IR,H-1-, C-13-NMR and MS data. The flow- vacuum pyrolyses of the tetrazoles 1-3, of a recently described tetrazoloaz onine 4 and of 1,5-diphenyltetrazole (5) at 1.33 mbar and temperatures betw een 400-550 degrees C were studied by GC/MS. The main reaction product of 1 was 6H-quinindoline whereas the principal products of 2, 3 and 4 were the corresponding ring contracted N-cyanoderivatives 11, 12 and 15, respectivel y. Diphenyltetrazole 5 afforded diphenylcarbodiimide and 2-phenyl-benzoimid azole. The comparative reaction mechanisms for 1-5 are discussed. The N-cya no-derivatives 11, 12 and 15 structurally are strongly related to recent an ti-amnesia drugs. (C) 1999 Elsevier Science B.V. All rights reserved.