in Wiley InterScience (www.interscience.wiley.com).Canthin-4-one, as well as 5-and 6-alkylcanthin-4-ones are readily available through reaction of 1-acyl-b-carbolines with Bredereck's reagent or dimethylacetamide acetals in anhydrous DMF. The intermediate enaminoketones readily undergo cyclization to the canthin-4-ones. The alkaloids tuboflavine and norisotuboflavine were prepared following this methodology.

Starting from 5,6‐dihydrocanthin‐4‐one, new penta‐ and hexacyclic ring systems (1,7b,14‐triazadi‐benzo[e,k]acephenanthrylenes, 1,7b,10,12‐tetraazabenzo[e]acephenanthrylenes) were built up using ring annelation reactions. The new compounds represent hybrids between the canthinones and several bioactive aromatic alkaloids J. Heterocyclic Chem., (2010).

No abstract

The first total synthesis of the β-carboline alkaloids arenarine A (1) and arenarine B (2) is described. Methanolysis of the α-bromoketone 9 gives 1 in good yield. Alternatively 1 can be obtained from the diazoketone 11 with boron trifluoride/methanol in poor yield. Reduction of 1 with sodium borohydride gives racemic arenarine B (2). Regioselective homolytic methylation of norharmane (4) with tert-butyl hydroperoxide/ferrous sulfate gives the alkaloid harmane (6).

Based on the chemotype of canthin‐4‐one alkaloids with moderate antimicrobial activity, a collection of variously substituted canthin‐4‐ones and desaza analogs were synthesized. Key steps in the syntheses were regioselective halogenations of (desaza) canthin‐4‐one, followed by Pd‐catalyzed cross‐coupling reactions. The in vitro screening for antimicrobial activity revealed that two 5‐substituted canthin‐4‐ones (3‐pyridyl, 2‐bromophenyl) exhibit significant activity against Streptococcus entericus, coupled with high selectivity and the lack of cytotoxicity against mammalian cells. The intact canthin‐4‐one ring system was demonstrated to be essential for antibacterial activity.

For Abstract see ChemInform Abstract in Full Text.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

No abstract