反应详情

Preparation of methyl 5-(aminomethyl)pyrrole-2-carboxylate hydrochloride (X) can be accomplished by the approach shown in Scheme 11. A three-step conversion of pyrrole into methyl 5-formylpyrrole-2-carboxylate has been described (Org. Syn., Coll Vol. 4, 1963, p831). Alternatively, Muchowski (Tetrahedron Lett., 1988, 29, 777) has described the bis(dimethylamino)azafulvene dimer resulting from treatment of 2-formylpyrrole with dimethylamine. Such species may be lithiated at low temperatures and captured with a variety of electrophiles, including methyl chloroformate, to also give methyl 5-formylpyrrole-2-carboxylate. The aldehyde group is then converted to the oxime under standard conditions and finally reduced by catalytic hydrogenation in the presence of hydrochloric acid to give the target linker (X). ##STR44##