Triazole phosphonates. Electrophilic substitution of 1‐substituted‐1H‐1,2,4‐triazoles via lithiated triazole intermediates

Abstract
The metalation chemistry of several 1‐substituted‐1H‐1,2,4‐triazoles has been investigated. When various alkyl groups were incorporated in the 1‐position, lithiation proceeded exclusively at C‐5. The 1‐trityl‐, 1‐methyl‐, and 1‐benzyl‐5‐lithio‐1,2,4‐triazoles were stable at −78° and reacted cleanly with a variety of electrophiles. The 1‐benzyl and 1‐methyl derivatives were synthetically more versatile and could be successfully utilized to prepare several examples of the previously unknown 1,2,4‐triazol‐5‐yl phosphonates.