RESUMEN
Bioassay-directed fractionation of the organic extract of Mallotus philippinensis gave five compounds (1-5), the most active of which against Mycobacterium tuberculosis was a new compound, 8-cinnamoyl-5,7-dihydroxy-2,2-dimethyl-6-geranylchromene (1) for which the name mallotophilippen F is suggested. Compound (2), 8-cinnamoyl-2,2-dimethyl-7-hydroxy-5-methoxychromene, was isolated from a natural source for the first time, while the remaining three compounds, rottlerin (3), isoallorottlerin=isorottlerin (4) and the so-called "red compound," 8-cinnamoyl-5,7-dihydroxy-2,2,6-trimethylchromene (5), had been isolated previously from this plant. All compounds were identified by analysis of their spectra including 2D-NMR, which was used to correct the literature NMR spectral assignments of compounds 2-4. The C-13 NMR of 5 is reported for the first time.
Asunto(s)
Antituberculosos/química , Antituberculosos/farmacología , Mallotus (Planta)/química , Estructura Molecular , Mycobacterium avium/efectos de los fármacos , Mycobacterium tuberculosis/efectos de los fármacosRESUMEN
The structure of an unexpected compound from the dehydration of an aldol addition product has been determined using 1-D and 2-D NMR techniques. This reaction is the last step in a new synthetic approach to the galanthan ring system. Complete 1H and 13C NMR assignments for two synthetic precursors are also reported.
Asunto(s)
Cetonas/química , Agua/química , Isótopos de Carbono/análisis , Cristalografía por Rayos X , Hidrógeno/análisis , Espectroscopía de Resonancia Magnética , Estructura MolecularRESUMEN
A five-step, atom-efficient synthesis of the Galanthan tetracyclic skeleton has been developed. The key step is an unusual intramolecular de Mayo reaction using an isocarbostyril substrate with a functionalized tether on nitrogen. The target molecule is produced in 35% overall yield from isocarbostyril.