Geovane G. de Oliveira

Azafluorenones and azaanthraquinone from Guatteria dielsiana

Abstract Trunkwood of Guatteria dielsiana afforded eight alkaloids and one triterpene. Three of the alkaloidal constituents are oxoaporphines: liriodenine, O -methylmoschatoline and isomoschatoline; four are 1-azafluorenones: onychine, the only previously known representative of this group, and three novel compounds of this rare type, 6-methoxyonychine, dielsine (1-aza-4-methyl-2-oxo-1,2-dihydrofluorenone) and dielsinol (1-aza-4-hydroxymethyl-2 oxo-1,2-dihydrofluorenone). The last alkaloid is dielsiquinone (1-aza-3-methoxy-4-methyl-2-oxo-1,2-dihydro-9,10-anthracenedione), the second representative of a new class of quinones of which cleistopholine was the only one previously known. The triterpene is polycarpol whose presence is of chemotaxonomic significance since this metabolite seems to be exclusive to the Annonaceae.

Isoflavonoids from Cyclolobium species

Abstract (3 R )-Claussequinone (7-hydroxy-4′-methoxyisoflavanquinone is the principal constituent of Cyclolobium clausseni Benth. and C. vecchii A.

Lignans and naphthoquinones from Tabebuia incana

Abstract The trunkwood of Tabebuia incana afforded the lignans pawlownin and cycloolivil as the major constituents together with a cycloolivil acetonide, la

Synthesis of benzyl and methyl 3-benzamido-2,3,6-trideoxy-2-fluoro-β-l-galactopyranoside: Protected C-2 fluoro analogues of daunosamine

Abstract The reaction of benzyl 2-benzamido-4,6- O -benzylidene-2-deoxy-3- O -tosyl-α- d -glucopyranoside or benzyl 4,6- O -benzylidene-2,3-benzoylepimino-2,3-dideoxy-α- d -allopyranoside with anhydrous tetrabutylammonium fluoride in hexamethylphosphoric triamide gave ∼40% of benzyl 3-benzamido-4,6- O -benzylidene-2,3-dideoxy-2-fluoro-α- d -altropyranoside ( 6a ). Transformation of 6a into benzyl 3-benzamido-2,3,6-trideoxy-2-fluoro-α- d - arabino -hex-5-enopyranoside ( 13a ) was carried out by well-established methodology. Hydrogenation of the double bond in 13a furnished the title compound in good yield. Methyl 3-benzamido-2,3,6-trideoxy-2-fluoro-β- l -galactopyranoside was also prepared in nine steps from 2-amino-2-deoxy- d -glucose.

Geovanine, a new azaanthracene alkaloid from Annona ambotay aubl.

Abstract The new azaanthracene geovanine was isolated from the trunkwood of Annona ambotay Aubl. together with liriodenine, O-methylmoschatoline and other known substances, the flavonoids kaempferol, quercetin, (+)-dihydrokaempferol, (+)-dihydroquercetin, (±)-eriodictiol and (+)-catechin and the steroids sitosterol and 5α-stigmastan-3,6-dione.

Isoflavonoids from Myroxylon peruiferum

Abstract Considerable differences in flavonoid composition of the trunkwood characterize different specimens of Myroxylon balsamum (L.) Harms. Only calycosin among the 11 flavonoids found in M. peruiferum L.f., presently considered synonymous with M. balsamum , had previously been located in the latter species. Two of these flavonoids, 2′-hydroxy-7,3′,4′-trimethoxyisoflavanone and 2′-hydroxy-7,3′,4′-trimethoxyisoflavone are new natural products.

Structure and absolute configuration of the sesquiterpenoid emmotins

Abstract The trunk wood of Emmotum nitens (Icacinaceae) contains the aromatic sesquiterpenes (2R,3S)-2-hydroxy-3-(2′-hydroxyisopropyl)-5,8-dimethyl-1-oxo-1,2,3,4-tetrahydronaphthalene (emotin-F), 2-hydroxy-3-(2′-hydroxyisopropyl)-5,8-dimethylnaphthalene (emmotin-G) and 3-(2′-hydroxyisopropyl)-5,8-dimethyl-1,2-naphtho-quinone (emmotin-H). The identity of the carbon skeletons of these emmotins was proved by conversion of all three into an identical quinoxaline derivative. The nature of this skeleton and the absolute configuration of emmotin-F, as well as of the previously described emmotins A and B, was established by conversion of emmotin-F into (+)-occidol.

Zeyherol, a dilignol from Zeyhera digitalis☆

Abstract The stem wood of Zeyhera digitalis (Bignoniaceae) contains, besides d -glucose, vanillic acid, veratric acid and lapachol, a natural dilignol type compound for which the structure of 2,2′-dihydroxy-3,3′-dimethoxy-5-ω-oxo- E -propenyl)-5′-(ω-hydroxy- Z -propenyl)-biphenyl is proposed.

Isoflavone evolution in Monopteryx

Abstract Monopteryx inpae contains six 5,7-dihydroxyisoflavones, three of which, such as the novel 5,7-dihydroxy-8,3′,4′-trimethoxy derivative, have additionally methoxyls on ring A. All three isoflavones of M. uaucu are, by contrast, 7-hydroxy-8-methoxy derivatives. From the chemical standpoint, the former species thus appears to be more primitive than the latter.

Sesquiterpenoid emmotins from two Poraqueiba species

Abstract The phytochemical examination of the trunkwood of Poraqueiba guianensis afforded two novel emmotins, emmotin-Z [(2R, 3S)-2,6-dihydroxy-3-(2′-hydroxyisopropyl)-5-formyl-8-methyl-1,2,3,4-tetrahydronaphthalene] and its 6-O-methyl ether, two known seco-iridoids, secologanoside and its methyl ester, both of them obtained as natural products in their pure form, a new triterpenoid acid, icacinic acid reported elsewhere, and a rare lignan, 1-hydroxypinoresional, along with sitosterol, its 3-O-β- d -glucoside and glucose. Emmotin-Z was also isolated from P. paraensis, besides pinoresinol.