Alkylation of 5-Substituted Tetrazoles with Various Alcohols in 1,2-Dichloroethane in the Presence of BF3·Et2O

The alkylation of 1 H -tetrazole, 5-methyl-1 H -tetrazole, and 5-phenyl-1 H -tetrazole with primary, secondary, and tertiary alcohols, including benzylic and allylic ones, have been studied in 1,2-dichloroethane in the presence of boron trifluoride–diethyl ether complex. Neither primary nor secondary saturated alcohols alkylated tetrazoles in the given system. Tertiary alcohols such tert -butyl alcohol and adamantan-1-ol reacted with unsubstituted and 5-substituted tetrazoles to give 70–85% of the corresponding 2-alkyl-5-R-tetrazoles with high regioselectivity. The alkylation of 1 H -tetrazole with benzyl alcohol afforded 55% of 2-benzyl-2 H -tetrazole as the only product. The alkylation of 1 H -tetrazole with various allylic alcohols led to the formation of mixtures of 2-alkyl-2 H -tetrazoles with isomeric alkyl substituents.