According to four different methods, various types of N-acylpyrazoles
were prepared from the corresponding pyrazoles and carboxylic acids or
their acid chlorides. Although N-acylpyrazoles were inert to alcohols
under neutral or weakly basic conditions, the alcoholysis was dramati
cally accelerated by the action of strong acid or base. On the basis o
f these chemical properties, the regioselective synthesis of methyl be
nzyl 2,2-dimethylglutarate was achieved by selective protection and fu
nctionalization of a carboxylic acid derivative using N-acylpyrazoles.