Functionalization of 4-bromobenzo[c][2,7]naphthyridine via regioselective direct ring metalation. A novel approach to analogues of pyridoacridine alkaloids

• Benedikt C. Melzer,
• Alois Plodek and
• Franz Bracher

Beilstein J. Org. Chem. 2019, 15, 2304–2310, doi:10.3762/bjoc.15.222

• -mn]acridones has been worked out. Keywords: alkaloids; cyclization; metalation; naphthyridine; pyridoacridine; Introduction Polycyclic aromatic alkaloids are a unique class of natural products with a broad pattern of biological activities. One of the most prominent classes are the so-called

• pyridoacridine alkaloids to be found in diverse marine sources (tunicates, sponges). Their chemistry, pharmacology and biosynthesis have been the subject of a couple of review articles [1][2][3][4]. Another source of polycyclic aromatic alkaloids are tropical plants, e.g., the Annonaceae family [5]. A very

• biosyntheses of known alkaloids, a “pyridoacridine family tree” which is claimed to be useful for designing total synthesis, but also for predicting yet undiscovered alkaloids from this chemotype [6]. Only two tricyclic benzo[c][2,7]naphthyridine alkaloids, perlolidine (6; from rye grass, Lolium perenne) [7

A novel approach to oxoisoaporphine alkaloids via regioselective metalation of alkoxy isoquinolines

• Benedikt C. Melzer and
• Franz Bracher

Beilstein J. Org. Chem. 2017, 13, 1564–1571, doi:10.3762/bjoc.13.156

• our recent work on the synthesis of polycyclic aromatic alkaloids like pyridoacridine, benzylisoquinoline-type and oxoaporphine alkaloids using direct ring metalations of heterocycles as vital step [13][21] we intended to develop a novel and more flexible access to oxoisoaporphine alkaloids. Again we

Pyridinoacridine alkaloids of marine origin: NMR and MS spectral data, synthesis, biosynthesis and biological activity

• Louis P. Sandjo,
• Victor Kuete and
• Maique W. Biavatti

Beilstein J. Org. Chem. 2015, 11, 1667–1699, doi:10.3762/bjoc.11.183

• on pyridoacridine-related metabolites as one biologically interesting group of alkaloids identified from marine sources. They are produced by marine sponges, ascidians and tunicates, and they are structurally comprised of four to eight fused rings including heterocycles. Acridine, acridone

• reported, pyridoacridine 13C NMR data. Observations have been made on the delocalization of electrons and the presence of some functional groups that lead to changes in the chemical shift of some carbon resonances. The lack of mass spectra information for these alkaloids due to the compactness of their

• phosphatase B (PtpB) [31] and serine protease [32]. The focus of this review is on pyridoacridine-related metabolites as one of the many interesting groups of alkaloids produced from marine sources. They are generally produced by marine sponges, ascidians [33] and tunicates [34] and they are structurally