5-Substituted-lH-tetrazoles

Momose, Y, Maekawa, T., Odaka, H., Ikeda, H., Sohda, T. Novel 5-substituted-lH-tetrazole derivatives as potent glucose and lipid lowering agents. Chem. Pharm. Bull. (Tokyo) 2002, 50(1), 100-111. 

Herr, R.J. (2002) 5-Substituted-lH-tetrazoles as carboxylic add isosteres medidnal chemistry and synthetic methods. Bioorganic and Medicinal Chemistry, 10, 3379-3393. 

TBAF efficiently unmasks nucleophilic azide for C-N bond formation. TBAF stimulated the reaction of benzonitrile with TMSN3 to form 5-substituted IH-tetrazoles (eq 45). Under similar conditions, 4-aryl-lH-l,2,3-triazoles can be synthesized by TBAF-catalyzed cycloadditions of electron poor nitroolefins (eq46). 2 - 25... 

In 1998, Kociensky et al. proposed a variation of this method that obviated the use of Barbier-type conditions and made this sequence more compatible with complex aldehydic substrates [137]. They also extended the range of sulfone heterocycles to l-isoquinohnoyl, l-methyl-2-imidazoyl, 4-methyl-2-imidazoyl, 4-methyl-l,2,4-triazol-3-yl, and l-phenyl-lH-tetrazol-5-yl (hereafter denoted PT), with the latter system being the most promising. Among the various trends that they observed from 96 comparative experiments, it was deduced that the -alkyl PT-sulfones gave better yields than their BT-substituted counterparts (suggesting that PT sulfones are less prone to self-condensation). Moreover, careful combination of the solvent and the counter ion proved to have a profound effect on the yield and the stereochemical outcome of the elimination. 

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