On the relative strength of the 1H-tetrazol-5-yl- and the 2-(triphenylmethyl)-2H-tetrazol-5-yl-group in directed ortho-lithiation

ortho-Lithiation followed by electrophilic trapping of N-unsubstituted and N2-triphenylmethyl substituted 5-aryltetrazoles, further substituted with another ortho-director at the para position of the aryl ring, resulted in the formation of regioisomers of which the ratio depended on the competing para-substituents. By such intramolecular competition experiments, the ortho-directing strength of these tetrazol-5-yl groups in comparison to some commonly employed ortho-directors were found to be: OMe<1H-tetrazol-5-yl<CONEt2<2-(triphenylmethyl)-2H-tetrazol-5-yl<NHCOCMe3, OCONEt2.