dc.description.abstract | Benzyl 3,5-dimethyl-pyrrole-2-carboxylate, a very useful pyrrole in porphyrin and dipyrromethene
synthesis, can be synthesized via the Knorr-type reaction, but in low yield. Alternative routes to
benzyl 3,5-dimethyl-pyrrole-2-carboxylate have been developed involving the trans-esterification of
ethyl 3,5dimethyl-pyrrole-2-carboxylate and the de-acetylation of benzyl
4-acetyl-3,5-dimethyl-2-carboxylate, both precursors being easily obtained using the Knorr reaction.
These traditional methods involve treatment of the known products with a strong basic solution or
heating for extended periods which often lead to decomposition. The use of microwave energy to
promote these two reactions proves to be an extremely efficient way to obtain benzyl 3,5
-dimethyl-pyrrole-2-carboxylate quickly, in high yield, and in excellent purity with no need for
recrystallization. Of particular note is the use of catalytic sodium methoxide in benzyl alcohol,
rather than stoichiometric amounts of sodium benzoxide, to effect benzylation. | en_US |