Julio G. Urones

Ambergis compounds from labdanolic acid

Abstract Labdanolic acid (Cistus ladaniferus) is transformed into derivatives with amber odor. The strategy used allowed a process in which the oxidative decarboxylation reaction was carried out with the hydroxyl group protected.

A diterpene alcohol from Halimium viscosum

Abstract A hexane extract of Halimium viscosum collected at La Fregeneda (Salamanca, Spain) yielded a new diterpene alcohol, tormesol. Its structure was determined by chemical transformations and NMR spectroscopy with 1 H 1 H (COSY), 13 C 13 C (2D-inadequate) and 1 H 13 C (one bond and long range correlations) two-dimensional experiments.

Conjugate addition to (α,β)(α′,β′)-diendioate esters by lithium (α-methylbenzyl)benzylamide: tandem addition–cyclisation versus double addition

Abstract Strategies for obtaining either the products from tandem conjugate addition–cyclisation or from double addition in the highly stereoselective addition of lithium ( R )-(α-methylbenzyl)benzylamide to (α,β)(α′,β′)-diendioate esters are demonstrated.

ASYMMETRIC SYNTHESIS OF (R)- AND (S)-METHYL (2-METHOXY-CARBONYLCYCLOPENT-2-ENYL)ACETATE AND (R)- AND (S)-2-(2-HYDROXY-METHYL-CYCLOPENT-2-ENYL)ETHANOL

Abstract ( R )- and ( S )-Methyl (2-methoxycarbonylcyclopent-2-enyl)acetate 1 and ( R )- and ( S )-2-(2-hydroxymethyl-cyclopent-2-enyl)ethanol 2 have been obtained from dimethyl (E,E)-octa-2,6-diendioate 3 by a diastereoselective tandem conjugate addition protocol, from ( R )- and ( S )-lithium (α-methylbenzyl)benzylamide 4 respectively.

Chemistry of zamoranic acid. Part V Homochiral semisyntheses of active drimanes: Pereniporin B, polygodial and warburganal

Abstract Methyl 14,15-dinor-13-oxo-7-labden-15-oate was obtained from acid zamoranic acid methyl ester. The former by photochemical cleavage yielded methyl 7,9(11)-drimadien-12-oate, whose chemoselective epoxidation afforded methyl 9α,11-epoxy-7-drimen-12-oate, which is the key synthetic precursor for pereniporin B, polygodial and warbuganal.

Chemistry of zamoranic acid. Part IX homochiral synthesis of polygodial and warburganal from 17-acetoxy-7-labden-15-ol

Abstract 14,15-di nor -17-acetoxy-7-labden-13-one, 4 was prepared from zamoranic acid methyl ester 5 . Photochemical cleavage of 4 gave 12-acetoxy-7,9(11)-drimadiene, 3 , in 75% overall yield. The chemo- and diastereoselective epoxidation of 3 afforded 12-acetoxy-9α and 9β(11)-epoxy-7-drimene, 17 and 18 in 4:1 ratio. Ring-opening of 17 (or the mixture 17 18 ) using BF 3 ·Et 2 O or ring-opening of the mixture 17 18 lead to the synthetic precursor of polygodial: (9 R )-12-acetoxy-drimen-11-al, 20 , with a 90% diastereoisomeric excess. The chemo- and diastereoselective cis -hydroxylation of diene 3 led to the synthetic precursor of warburganal 9α,11,12-trihydroxy-7-drimene, 29 with 47% yield. Polygodial and warburganal were prepared from zamoranic acid methyl ester in 55 and 27% overall yield, respectively.

Acetophenones and terpenoids from Senecio Gallicus

Abstract Six new compounds isolated from the aerial part of Senecio gallicus were: 7,11,15-trimethyl-3-methylene hexadecan-1,2-diol diacetate; 7,11,15-trimethyl-3-methylenehexadecan-1,2-diol; 3,5-bis(3-methyl-2-butenyl)-4-acetoxyacetophenone; 3-(2-hydroxy-3-methyl-3-butenyl)-5-(3-methyl-2-butenyl)4-hydroxacetophenone; 3-(2,3-dihydroxy-3-methyl-butyl)-5-(3-methyl-2-butenyl)-4-hydroxyacetophenone and 1,10-epoxy-8α-hydroxy eremophilenolide.

Labdane diterpenoids from Halimium viscosum and H. verticilatum

Abstract In addition to three known acids, six new diterpenoid acids with a labdane skeleton, were isolated from the acid fraction of Halimium viscosum . Fou

Monoterpene derivatives from the essential oil of Aristolochia longa

Abstract Two new pinane monoterpenes, pin-2-en-8-ol and its acetyl derivative, and also β-caryophyllene, caryophyllene oxide, linalool and bornyl acetate were isolated from the essential oil of the aerial parts of Aristolochia longa. From the volatile fraction of the underground part of the plant only the tricyclic sesquiterpenes calarene, maaliol and 1(10)-aristolen-2-one were isolated.

Flavonoids from Polygonum minus.

Abstract Two new components were isolated from the ether extract of Polygonum minus ; a flavone: 6,7-methylenedioxy-5,3′,4′,5′-tetramethoxyflavone and a methyl flavonol: 6,7-4′,5′-dimethylenedioxy-3,5,3′-trimethoxyflavone. Their structures were determined by spectroscopic methods.