Dayar Arbain

Synthesis and Absolute Configuration of (-)-Normalindine

The first chiral synthesis of the Strychnos and Ophiorrhiza alkaloid (−)-normalindine has been accomplished through a route starting from l-alanine methyl ester and exploiting intramolecular oxazole-olefin Diels-Alder reaction. As a result, the absolute stereochemistry of normalindine has been defined as represented by formula (−)-1.

Cyclopeptide alkaloids from Antidesma montana

Abstract Two cyclopeptide alkaloids, AM-1 and AM-2, were isolated from the leaves and terminal branches of Antidesma montana . By spectroscopic methods AM-1 was shown to be 2-dimethylamino-3-phenyl- N -[3-(1-methylethyl)-7-(2-methylpropyl)-5,8-dioxo-2-oxa-6,9-diazobicyclo[ω.2.2]hexadeca-10,12,14,15-tetraene-4-yl]propanamide and AM-2 to be 2-dimethylamino-3-phenyl- N -[3-(1-methylethyl)-7-(2-methylpropyl)-5,8-dioxo-2-oxa-6,9-diazobicyclo[ω.2.2]hexadeca-12,14,15-triene-4-yl]propanamide. These structures have previously been proposed for myrianthine B and aralionine B, respectively, but the reported physical properties differ markedly from those of AM-1 and AM-2. However, direct comparison of AM-1 with an authentic sample of myrianthine B confirmed their identity. A GC method was used to establish the chirality of the isoleucine in AM-1, AM-2 and myrianthine B as l . The chirality of N , N -dimethylphenylalanine in AM-1 and myrianthine B and of N -methylphenylalanine in AM-2 was also found to be l .

Chemical constituents from tiger's betel, Piper porphyrophyllum N.E.Br. (Fam. Piperaceae).

Seven flavonoid compounds have been isolated from the aerial parts of tigers betel (Piper porphyrophyllum), which were identified as 5,7-dimethoxyflavone, 4′,5,7-trimethoxy-flavone, 3′,4′,5,7-tetramethoxyflavone, 4′-hydroxy-3′,5,7-trimethoxyflavone, 5-hydroxy-3′,4′,7-trimethoxyflavone, 4′,5-dihydroxy-3′,7-dimethoxyflavone and 5-hydroxy-7-methoxyflavanone. The identification of all compounds was achieved by physical properties and spectroscopically. These data were also confirmed by comparison with previously reported spectral data. Flavonoid compounds with high content in P. porphyrophyllum can probably be used as a chemical marker for this Piper species.