Iodo-l-Methylpyrrole

The deprotonation of 1 -alkylpyrroles proceeds considerably less easily than that of furan and thiophene. A large excess of 1-methylpyrrole is required to obtain good results if butyllithium in THF is used (see Exp. 8), in which case the metallation has a synthetically acceptable rate at 20 to 30 °C. Complexation of butyllithium with t-BuOK causes an enormous enhancement of the deprotonation rate, as is shown below it is not necessary to use the pyrrole derivative in excess. 

N-Methylpyrrole can be lithiated very quickly using BuLi TMEDA in an apolar solvent (compare Exp. 14). This method is more suitable than the metallation with BuLi f-BuOK described in Exp. 39 if condensations with enolisable carbonyl 

A suspension of 2-lithio-l-methylpyrrole in ca. 80 ml of hexane is prepared from 

Too high local concentrations of iodine may give rise to reaction with TMEDA. 

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