Recent advances in the chemistry of lignans

Biscarpamontamines A and B, an Aspidosperma−Iboga Bisindole Alkaloid and an Aspidosperma−Aspidosperma Bisindole Alkaloid, from Tabernaemontana sphaerocarpa

“…Fractions 8 and 11 were recrystallized to give vobtusine (3) in CHCl 3 -MeOH (9:1) and vobtusine lactone (4) in CHCl 3 -MeOH (20: 1), respectively. The residue of fraction 8 was subjected to ODS HPLC (45 f 80% MeOH-0.1% TFA(aq), 35 min) to give vobasine, and then the fourth eluted fraction was also subjected to ODS HPLC (32% MeCN-0.1% TFA(aq)) to give 3-hydroxyvobtusine (5)…”

“…Tabernaemontana species so far have been shown to produce various skeletal types of indole alkaloids, including iboga-type alkaloids such as ibogamine, aspidosperma-type alkaloids such as taberhanine, and vobasinyl−ibogan bisindole alkaloids such as conodiparine A . However, only vobasine-type alkaloids such as tabernaemontanine and dregamine have been isolated from T. sphaerocarpa . In our search for structurally and biogenetically interesting alkaloids from tropical plants found in Indonesia, two new bisindole alkaloids, biscarpamontamine A ( 1 ), having an aspidosperma−iboga-type skeleton, and biscarpamontamine B ( 2 ), based on an aspidosperma−aspidosperma-type skeleton, were isolated from the stems of T. sphaerocarpa , together with vobtusine ( 3 ), vobtusine lactone ( 4 ), 3-hydroxyvobtusine ( 5 ), ibogamine, voacangine, 3-hydroxyvoacangine, and vobasine .…”

Enantiospecific Total Synthesis of (−)-Anhydromacrosalhine-methine and Partial Synthesis of the Antiamoebic Bisindole Alkaloid (−)-Macrocarpamine1

“…During the last several decades, more than 80 macroline/sarpagine-related indole alkaloids have been isolated from Alstonia macrophylla Wall, Alstonia muelleriana Domin, and other Alstonia species. , Among these alkaloids, at least 18 are bisindoles including (−)-macrocarpamine ( 1 ), villalstonine ( 2 ), and macralstonine ( 3a ). Interest in macroline/sarpagine alkaloids isolated from Alstonia species originated as a result of folk tales that described the medicinal properties of these plants. , For example, the hypotensive base macralstonine 3a , isolated from A. macrophylla Wall, , is a member of this family. The biomimetic interconversions of Alstonia alkaloids and the coupling reactions of monomeric indoles into bisindoles were pioneered by LeQuesne. − Recently, the total synthesis of macroline 4 has resulted in the partial synthesis of macralstonine 3a (Scheme ); the addition of 4 to natural alstophylline 5 11 was carried out under the same conditions employed for the partial synthesis of the antimalarial alkaloid villastonine ( 2 ) …”

Catharanthus Alkaloids XXXVII. 16-Epi-Z-Isositsirikine, a Monomeric Indole Alkaloid with Antineoplastic Activity from Catharanthus roseus and Rhazya stricta

“…The reaction mixture, when poured into cold water, extracted with chloroform (3 x 10 ml), dried over Na2SG4 and evaporated in vacuo afforded a residue of 3 (5.5 Líaih4 reduction OF 1.-A solution of the isolate (1, 3 mg) in anhydrous ether (5 ml) was treated with a small quantity (approximately 1 mg) of Li A1H4 and the mixture stirred under N2 at room temperature for 2 h. The reaction was terminated by the slow addition of 2 ml of water, followed by extraction with chloroform (3x3 ml), and was dried over Na2S04 and evaporated. The product (2 mg) was the diol 4, displaying ms, m/z (%) 326 (M+, 83), 309 (17), 295 (26), 261 (13), 251 (84), 247 (38), 246 (41), 244 (16), 183 (36), 170(57), 169(100), and 156(51). Ketalization of diol 4.-To a solution of the diol 4 (2 mg) in dry acetone (2 ml) was added /.…”