Eliseo Seoane

Constituents of a hexane extract of Phoenix dactylifera

Abstract In addition to known compounds, two new steroid diones, 5α-stigmast-22-en-3,6-dione and 5α-campestan-3,6-dione, were isolated from stems of Phoenix dactylifera .

Flavones, sesquiterpene lactones and glycosides isolated from Centaurea aspera var. Stenophylla

Abstract From the alcoholic extract of Centaurea aspera var. stenophylla benzoic acid, p-hydroxybenzoic acid, apigenin, 6-methoxyluteolin, 11,13-dehydromelitensin, melitensin, stenophyliolide, ethyl-7-O-apigenin-glucuronate and the glucosides of sitosterol and stigmasterol were isolated and characterized. Stenophyllolide was shown to be 9,15-dihydroxygermacra-1(10),4,11-trien-12,6-olide.

Sesquiterpene lactones, waxes and volatile compounds from Artemisia herba-alba subspecies Valentina

Abstract The structures of two sesquiterpene lactones isolated from Artemisia herba-alba subsp. valentina have been determined by spectroscopic methods. One of these was dihydroreynosin, the other was a new compound assigned the name torrentin. The chemical compositions of a wax and a hydrocarbon fraction from the essential oil have also been investigated.

Total syntheses of (+)-temisin, (+)-melitensin and related elemanolides from (−)-artemisin

Abstract (+)-Temisin, (+)-melitensin, and related sesquiterpene lactones have been synthesized from (-)-artemisin.

Two polyhydroxystilbenes from stems of Phoenix dactylifera

Abstract From stems of Phoenix dactylifera trans-3,5,3′,5′-tetrahydroxy-4-methoxystilbene has been isolated as a major component; cis-3,5,3′,5′-tetrahydroxy-4-methoxystilbene and trans-3,5,4′-trihydroxystilbene were isolated as minor components. Other metabolites from the biogenetic route to these stilbenes were also characterized.

Free and bound hydroxyl and carboxyl groups in the cutin of Quercus suber leaves

Abstract The number of free and bound hydroxyl and carboxyl groups of the cutin of Quercus suber leaves was investigated by the lithium borohydride hydrogenolysis of mesyl-cutin compared with the lithium borohydride hydrogenolysis of untreated cutin. Fifty per cent of the vic -diol groups of the trihydroxy C 18 acid component and twenty five per cent of the secondary hydroxyl groups of the dihydroxy C 16 acid component are free. The rest of the secondary and all of the primary hydroxyl groups are esterified; all carboxyl groups are esterified.

Formation of 1-hydroxycyclopropanecarbonitrile ring in bicyclic systems

Abstract Reaction of α-methanesulfonyloxycycloalkanones with KCN in dimethylformamide is examined; this proceeds, with high yield, to give in some cases l-hydroxybicyclocarbonitriles and in other cases 2-cyanooxiranes. Open chain α-methanesulfonyloxyalkanones afford 2-cyanooxiranes.

9α,15-Dihydroxygermacra-1(10),4-dien-11β,13-dihydro-6α,12-olide, a germacranolide isolated from Centaurea aspera subsp. stenophylla

Abstract A new germacranolide, isolated from Centaurea aspera subsp. stenophylla, was identified as 9β,15-dihydroxygermacra-1 (10)4-dien-11β,l3-dihydro-6α,12-olide by spectroscopic evidence and partial synthesis.

Selective favorskii rearrangement in macrocyclic rings

Abstract A mixture of 2,2-dibromo-12-chlorocyclododecanone (IIa) and 2,12-dibromo-2-chlorocyclododecanone (IIb) by Favorskii rearrangement gave selectively methyl 2-chloro-1-cycloundecene-1-carboxylate (IIIa).

Structure and stereochemistry of stenophyllolide, a germacrolide from Centaurea aspera var. Stenophylla

Abstract A crystalline compound, named stenophyllolide, obtained from an extract of Centaurea aspera var. stenophylla was shown to be 9β,15-dihydroxygermacra-1(10),4,11-trien-6α,12-olide by X-ray analysis. The molecular structure of stenophyllolide was solved with orthorhombic space group P2 1 2 1 2 1 , a = 11.719 (5), b = 13.389 (5), c = 8.646 (5) A for Z = 4, by direct methods and refined to a final R of 0.06 for 1198 observed reflections.