A convenient synthesis of pseudoceratidine and three analogs for biological evaluation

The recently isolated marine natural product pseudoceratidine (1) has been synthesized from 2-trichloroacetylpyrrole. Bromination in the 4- and 5-position followed by nucleophilic displacement of the trichloromethyl group with spermidine gave 1 in 79 % yield. The procedure is general and can easily be adopted to the preparation of other derivatives. This was demonstrated by the synthesis of a 5,5ʹ-didebromo derivative (2) and two analogs (3–4). The compounds 1–4 have been tested for antibacterial activity and the results compared to a previous study. Also activity against the marine brine shrimp Artemia salina is reported.