N-Pyrrolylmagnesium halides (1, 2) react with alkyl bromoacetates (sa-d) in THF solution to give alkyl 2-pyrrolylacetates (sa-d) in good yields and with very high positional selectivity (C- 2: C-3 t 25). The high regioselectivity is rationalized in terms of an increased propinquity between C-2 and the bromoacetate methylene group as a consequence of coordination between magnesium and the carbonyl oxygen of the alkylating agent.(2, 5-Dimethylpyrrol- ...
