Protection of a primary amine group is achieved by incorporating it into an N-substituted 2,5dimethylpyrrole system. The method affords protection against strong bases and nucleophiles, heating with concentrated alkali, standard mineral acid work-up conditions, and various other reagents.Phenyl-, pyridyl-, thiazolyl-, and alkyl-amines have been studied. All give trisubstituted pyrroles in high yield ( > 80%) by reaction with hexane-2,5-dione. The pyrroles from the first three types are stable to storage; even the N-alkyl compounds can be used without difficulty. Regeneration of the amine group, by treatment with hydroxylamine hydrochloride, is efficient (ca. 80% yield) with the phenyl, pyridyl, and alkyl compounds but lesssatisfactory (6&65%generally but down to 25% in twocases) with the thiazolyl derivatives.

No abstract

The two types of condensation reactions shown in the scheme proceed through a common intermediate (III) in the presence of base.

Primäre Aminogruppen können als 2,5‐Dimethylpyrrole geschützt werden [(I)‐(III)].