Synthesis and reactions of tetrazolo[1,5-α]pyrimidines

The reaction of “magic malonates” (bis-2,4,6-trichlorophenyl malonates, 1 ) with 5-aminotetrazole ( 2 ) in the presence of triethylamine yields the ammonium salts 3 . Upon treatment of 3 with strong acids compounds 4a-d were obtained as a mixture of isomeric tetrazolopyrimidines ( A ) and 2-azidopyrimidines ( B ). Reaction of 4d with bromine or sulfuryl chloride leads by ring opening and decarboxylation to the halogenated tetrazole derivatives 5 or 7 , respectively. The action of acetic anhydride in pyridine on 3d yields the zwitterionic tetra-mic acid derivative 10.