Novel heterocyclic Tröger's base derivatives containing N-methylpyrrole units

Novel analogues of Tröger's base were prepared regioselectively from 4-amino-N-methylpyrrole carboxylates in good yield. Catalytic hydrogenation of dibenzyl-4,9-methano-1,6-dimethyl-4,5,9,10-tetrahydro-1H,6H-dipyrrolo-3,2-b:3′,2′-f]1,5]diazocin-2,7-dicarboxylate 2b led to 4,9-methano-1,6-dimethyl-4,5,9,10-tetrahydro-1H,6H-dipyrrolo-3,2-b:3′,2′-f]1,5]diazocin-2,7-dicarboxylic acid 3 which was used for the preparation of Tröger's base derivatives of natural antibiotics via an amide protocol. The novel heterocyclic Tröger's bases were characterized by a variety of spectroscopic techniques and compound 2b by X-ray crystallography. Incorporation of guanidine as the terminal group in the N-methylpyrrole Tröger's base skeleton opens the possibility for preparation of water soluble derivatives.