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.