A Synthesis of 1-Hydroxy-5-(2-substituted aryl)tetrazoles by Directed Lithiation

Abstract

Dilithiation of 1-hydroxy-5-aryltetrazoles with 2 equiv. of butyllithium in the presence of N,N,N´N´-tetra-methylethylenediamine enables the introduction of ortho-substituents into the aryl ring to form compounds (6a–e). The hydroxy group of 1-hydroxy-5-phenyltetrazole may be masked by alkylation with 9-anthrylmethyl chloride. The masking group is removed with 1,4-diazabicyclo[2.2.2]octane or migrated to N 3 by treatment with trifluoro-acetic acid to form the N-oxide (10).