Tetrazoles are synthetic heterocycles with numerous applications in organic chemistry, coordination chemistry, the photographic industry, explosives, and, in particular, medicinal chemistry. In organic chemistry, 5-substituted tetrazoles are used as advantageous intermediates in the synthesis of other heterocycles and as activators in oligonucleotide synthesis.
In drug design, 5-monosubstituted tetrazoles are the most important tetrazole derivatives because they represent nonclassical bioisosteres of carboxylic acids, with similar acidities but higher lipophilicities and metabolic resistance. In this review we focus on the preparation and further functionalization of these heterocycles.