martinelline and martinellic-acid

Natural products are rich sources of interesting scaffolds possessing a plethora of biological activity. With the isolation of the martinella alkaloids in 1995, namely martinelline and martinellic acid, the pyrrolo[3,2-c]quinoline scaffold was discovered. Since then, this scaffold has been found in two additional natural products, viz. incargranine B and seneciobipyrrolidine. These natural products have attracted attention from synthetic chemists both due to the interesting scaffold they contain, but also due to the biological activity they possess. This review highlights the synthetic efforts made for the preparation of these alkaloids and formation of analogues with interesting biological activity.

Topics: Alkaloids; Bignoniaceae; Biological Products; Chemistry Techniques, Synthetic; Pyrroles; Pyrrolidines; Quinolines

Herein, we describe the first asymmetric total synthesis of (-)-martinelline ((-)-2) and the second total synthesis of (-)-martinellic acid ((-)-1) by employing a tandem Mukaiyama-Mannich reaction/aminal cyclization as the key step.

Topics: Alkaloids; Chemistry, Organic; Cyclization; Pyrroles; Quinolines

[reaction: see text] A concise synthesis of the guanidine alkaloids, (+/-)-martinelline and (+/-)-martinellic acid, using a protic acid catalyzed 2:1 hetero Diels-Alder coupling reaction between N-Cbz 2-pyrroline and methyl 4-aminobenzoate, is described. Protic acid catalysis, rather than Lewis acid catalysis, was necessary to achieve the desired sense of diastereocontrol in the coupling reaction.

Topics: 4-Aminobenzoic Acid; Alkaloids; Anti-Bacterial Agents; Bradykinin Receptor Antagonists; Guanidine; para-Aminobenzoates; Pyrroles; Quinolines

[reaction: see text] The first total synthesis of martinellic acid, a naturally occurring bradykinin receptor antagonist, via a CuI-catalyzed coupling reaction of beta-amino ester 6 with 1,4-diiodobenzene and a guanylation reaction of secondary amine 3 under mild conditions as key steps, is described.

Topics: Alkaloids; Amines; Bradykinin Receptor Antagonists; Molecular Structure; Plant Roots; Plants, Medicinal; Pyrroles; Quinolines; Receptors, Bradykinin; Structure-Activity Relationship