Enrique Alvarez-Manzaneda

SYNTHESIS AND ANTITUMOR ACTIVITY OF PUUPEHEDIONE AND RELATED COMPOUNDS

Abstract The first enantiospecific synthesis of bioactive marine puupehedione ( 2 ) and related compounds from (−)-sclareol ( 11 ) is reported. The antitumor activity of these compounds was assayed and compared with that of the natural products.

Synthesis of Ambrox® from(-)-sclareol and (+)cis-abienol

Abstract Short and efficient syntheses of (−)-Ambrox® (12) from (−)-sclareol (1) and (+)-cis-abienol (11) are described. In constrast to previously described procedures, the transformation of 1 to 12, involving in the key step, an oxidative degradation by catalytic osmium tetroxide, in the presence of sodium periodate, has the advantage of using the more suitable sodium borohydride, as the reducing agent. The isolation and characterization of some reaction intermediates allowed us to confirm the degradation mechanism.

Achilleol A: A new monocyclic triterpene skeleton from Achillea odorata L.

A new triterpene 1a from Achillea odorata L. has been isolated, and its structure established on the basis of its spectroscopic properties as well as those of its acetylderivative 1b. 1a shows the first example of monocyclic triterpene skeleton, biosynthetized in the first step of cyclization of squalene oxyde.

Enantiospecific synthesis of (+)-puupehenone from (−)-sclareol and protocatechualdehyde

Abstract The first enantiospecific synthesis of the antitumor and cholesteryl ester transfer protein (CETP) inhibitor (+)-puupehenone (19) from (−)-sclareol (10) and protocatechualdehyde (4) is described. The key steps of the reaction sequence are the organoselenium-induced cyclization of the mixture of regioisomers 15a-b to give 16 and 17, with complete diastereoselectivity, and the simultaneous removal of benzyl and phenylselenyl groups of 16 and 17 by treating with Raney Ni.

Synthesis and antitumoral activities of marine ent-chromazonarol and related compounds

Efficient syntheses of ent-isozonarol (6a), ent-isozonarone (7a) and ent-chromazonarol (8) from (-)-sclareol (12) are described. 6a and 7a show a significative antitumoral activity.

SYNTHESIS OF WIEDENDIOL-A AND WIEDENDIOL-B FROM LABDANE DITERPENES

Abstract Two efficient enantiospecific syntheses of wiedendiol-A (1) from (−)-sclareol (7), via 11-bromo-8-drimene (11) and 8-drimen-11-al (3), are reported. The first enantiospecific synthesis of wiedendiol-B (2), via 8S,9S-driman-11-al (26), by two alternative routes starting from 7 and (+)-cis-abienol (8) is also described. 21 prepared from protocatechualdehyde (17) was used as aromatic synthon for preparing 1 and 2.

Terpenoids and sterols from the wood of Abies pinsapo

Abstract From the neutral fraction of the hexane extract of the wood of Abies pinsapo 11 sesquiterpenoids, seven diterpenoids, three triterpenoids and two sterols have been identified. Three of them are new natural products: 3β-hydroxy-13-epimanool, (23 R ,25 R )-3α-methoxy-9,19-cyclo-9β-lanostan-26,23-olide and (22 S )-5α-ergostane-3α,22-diol. Their structures were established by spectroscopic methods and chemical correlations.

Synthesis of Ambrox® from communic acids

Two routes for preparing Ambrox® (1) from the methyl esters of trans-communic acid (2b) and/or cis-communic acid (3b), via selective degradation of their side chains, stereoselective formation of the tetrahydrofurane ring, and reduction of the axial methoxycarbonyl group, are described.

Diterpenoids and cyclolanostanolides from Abies marocana

Abstract From the neutral fraction of a hexane extract of the leaves of Abies marocana, eight sesquiterpene hydrocarbons, 10 diterpenoids, and two triterpenoids have been identified. Seven are new natural products: labda-7,12Z,14-triene, labda-8(17),12Z,14-triene, labda-7,11E,13Z-triene and labda-8(17),11E,13Z-triene, 7α,18-dihydroxyabieta-8,11,13-triene, (23R)-3α-hydroxy-9,19-cyclo-9β-lanostan-26,23-olide and (23R)-3α-hydroxy-9,19-cyclo-9β-lanost-24-en-26,23-olide. Their structures have been established by spectroscopic methods and chemical correlations.

Endoperoxide diterpenoids and other constituents from Abies marocana

Abstract From the acid fraction of the hexane extract of the needles of Abies marocana three endoperoxide diterpenoids, methyl 12α-hydroxyabietate and a triterpenoid, in addition to other resin acids have been isolated.