Bromopyrrole derivatives

Forenza, S.L., Minale, L., Riccio, R. and Fattorusso, E., 1971. New bromopyrrole derivatives from the sponge Agelas oroides. J. Chem. Soc., Chem. Commun., 1971 1129. 

Garcia, E. E., Benjamin, L. E., Fryer, R. I., (1973). Reinvestigation into the structure of oroidin, a bromopyrrole derivative from marine sponge. J. Chem. Soc. D. Chem. Commun., 78-79. 

During the past few years several reports have appeared which describe the occurrence of btomocompounds also in sponges and now the Porifera phylum appears as one of the richest sources of bromine-containing metabolites. The next subsection considers the tyrosine-derived bromo compounds the bromopyrrole derivatives and miscellaneous metabolites are reviewed in subsection 1.2. 

More recently Stempien et al. have announced 173) the occurrence in an unidentified species of Agelas of a further bromopyrrole derivative with antibiotic activity, to which they assigned the structure 4-bromo-pyrrole-2-carbonylguanidine (31). 

The bromopyrrole derivatives have been reported from two Agelas and three Axinellida (Table 5) which indicate a relationship between Agelas and some Axinellida. 

Forenza, S., L. Minale, R. Riccio, and E. Fattorusso New bromopyrrole derivatives from the sponge Agelas oroides. Chem. Comm. 1971, 1129. 

Bromopyrroles are accessible from metallic derivatives quenched with bromine [62MI2 77MI1]. 

Li C-J, Schmitz FJ, Kelly-Borges M (1998) A New Lysine Derivative and New 3-Bromopyrrole Carboxylic Acid Derivatives from Two Marine Sponges. J Nat Prod 61 ... 

Regioselective bromination. This reagent is superior to NBS for bromination of pyrrole to provide 2-bromopyrrole. After conversion to the N-boc derivative,... 

In connection with such syntheses, Chang and Bag [53] also reported a synthetic route to tetramethyltetraphenylporphyrin from a pyrrole derivative. The required pyrroles were synthesized from bromopyrrole (9) and phenylboronic acid by means of a Pd(0)-catalyzed crosscoupling. The reaction proceeded well in DMF to give an essentially quantitative yield of the product 10 (Eq. (25)). 

This class of bromopyrrole alkaloids includes all those molecules whose cyclized skeleton can be formally derived through the formation of one (or more) C-C or C-N bonds within the oroidin framework. Consequently, we have found it very useful to classify these molecules according to the oroidin atoms involved in the formal cyclization. More than 40 molecules have been thus classified into six different groups. 

The synthesis of C-4/C-10 cyclic bromopyrrole alkaloids has been intensively explored, and several approaches to their pyrrolo[2,3-c]azepin-8-one ring system (bearing an imidazole-derived ring at position 4) have been proposed [63-65]. 

Phakellins (41, 42), tetracyclic derivatives in which both the pyrrole and the amidic nitrogen atoms are involved in the formation of a linkage with carbon atoms of the imidazole ring, represented the first members of the family of oroidin-related cyclic bromopyrrole alkaloids to be isolated. They were found in 1971 by Sharma et al. in the marine sponge Phakelliaflabellata their structure was confirmed by X-ray diffraction analysis of a single crystal of the monoacetyl derivative of 41 [70]. Complete spectral data were provided by the same authors a few years later [71]. 

---