That a nionobromination of I should be expected to yield the 2-bromo (11) rather than the 5- bromo isomer (111) follows both from electronic considerations and from the previous demonstration by Fischer and Wieden~ ann~~ that electrophilic attack in the case of formylation does in fact lead to 2-formyl-3-methyl-4-carbethoxypyrrole (VII), 4b* 5a
