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Journals and Conferences
Cylindrospermopsin (CY), a sulfate ester of a tricyclic guanidine substituted with a hydroxymethyluracil, is a cyanobacterial toxin of increasing environmental import as it frequently occurs in drinking water reservoirs. As a toxin, CY mainly targets the liver but also involves other organs. In hepatocytes CY inhibits the synthesis of protein and of… (More)
A new phenolic derivative of aflatoxin B(1), appearing mainly in conjugated form, was identified as the principal urinary metabolite of aflatoxin B(1) in rhesus monkeys. Its identification in human urine might facilitate estimation of aflatoxin exposure in human populations.
This Highlight describes some of the recent synthetic work on imidazole-containing alkaloids isolated from marine sponges. Target molecules have been chosen which demonstrate synthetic strategies leading towards metabolites containing intact imidazole moieties as well as systems bearing modified imidazole rings.
several other alkaloids of this class. Allosecurinine (3), which is the C2 epimer of 1, is also a common alkaloid of this group, as is securitinine (4). The enantiomer of 3 (viroallosecurinine) is a natural product as well. Some additional common alkaloids of this group are (ÿ)-norsecurinine (5), whose ()-enantiomer is also naturally occurring, and… (More)
The present study establishes relationships between structure and reactivity for the pyrroloquinoline and phenanthroline quinones. The electrochemical reductions of 1,7- and 1,10-phenanthroline-5,6-quinones, like other quinones, are reversible and occur by 2e- transfer in a single step in aqueous solution and by two 1e(-)-transfer steps in aprotic media.… (More)
A stereoselective total synthesis of the structure 1 proposed for the freshwater cyanobacterial heptatotoxin cylindrospermopsin has been accomplished in approximately 30 operations starting from commercially available 4-methoxypyridine. Utilizing methodology developed by Comins, the tetrasubstituted piperidine A-ring unit of the hepatotoxin was efficiently… (More)
A new strategy for enantiospecific construction of the Securinega alkaloids has been developed and applied in total syntheses of (+)-14,15-dihydronorsecurinine (8), (-)-norsecurinine (6), and phyllanthine (2). The B-ring and C7 absolute stereochemistry of these biologically active alkaloids originated from trans-4-hydroxy-L-proline (10), which was converted… (More)
[reaction: see text] A 12-step total synthesis of the tricyclic heteroaromatic marine metabolite ageladine A has been achieved using a 6pi-azaelectrocyclization and a Suzuki-Miyaura coupling of N-Boc-pyrrole-2-boronic acid with a chloropyridine as key steps.