Serafín Valverde

Gentisic acid, a compound associated with plant defense and a metabolite of aspirin, heads a new class of in vivo fibroblast growth factor inhibitors.

Fibroblast growth factors are key proteins in many intercellular signaling networks. They normally remain attached to the extracellular matrix, which confers on them a considerable stability. The unrestrained accumulation of fibroblast growth factors in the extracellular milieu, either due to uncontrolled synthesis or enzymatic release, contributes to the pathology of many diseases. Consequently, the neutralization of improperly mobilized fibroblast growth factors is of clear therapeutic interest. In pursuing described rules to identify potential inhibitors of these proteins, gentisic acid, a plant pest-controlling compound, an aspirin and vegetarian diet common catabolite, and a component of many traditional liquors and herbal remedies, was singled out as a powerful inhibitor of fibroblast growth factors. Gentisic acid was used as a lead to identify additional compounds with better inhibitory characteristics generating a new chemical class of fibroblast growth factor inhibitors that includes the agent responsible for alkaptonuria. Through low and high resolution approaches, using representative members of the fibroblast growth factor family and their cell receptors, it was shown that this class of inhibitors may employ two different mechanisms to interfere with the assembly of the signaling complexes that trigger fibroblast growth factor-driven mitogenesis. In addition, we obtained evidence from in vivo disease models that this group of inhibitors may be of interest to treat cancer and angiogenesis-dependent diseases.

Stereoselective syntheses and reactions of chiral oxygenated α,β-unsaturated-γ- and δ-lactones

Abstract The syntheses of the chiral α,β-unsaturated lactones (+)-5, (−)-6, (+)-8, (+)-9, and (+)-10 have been efficiently achieved from readily available starting materials. The lactone (+)-5 has been synthesized in 7 steps from (R,R)-dimethyl tartrate (38–43% overall yield). The use of (+)-5 in formal syntheses of natural (+)-asperlin 4 and advanced intermediates for (+)-olguine 2 are also reported. The lactone (−)-6 has been prepared in 5 steps from (R)-malic acid (44–50% overall yield). It can be a useful precursor for the syntheses of branched chain and deoxy nucleoside analogues. The preparation of (−)-6 constitues formal syntheses of natural (+)-eldanolide 53 and the (+)-Geissman-Waiss lactone 54 (an intermediate for the syntheses of a variety of pyrrolizidine alkaloids). The lactones (+)-8, (+)-9 and (+)-10 have been synthesized from 3,4-di-O-acetyl-L-rhamnal 58. The highly diastereoselective transformations of (+)-9 and (+)-10, through sequential conjugate nucleophilic addition and enolate reaction, into densely functionalized chiral γ-lactones 12 are also reported.

The synthesis of (-)-anamarine

Abstract The enantiospecific total synthesis of (-)-anamarine, starting from D-glucose, has been carried out.

The use of l-tartaric acid in the synthesis of enanthiomerically pure compounds: synthesis of 4-O-benzyl-2,3-dideoxi-L- threo-hex-2-eno no-1,5-lactone.

Abstract The title compound was obtained through a seven steps sequence and using - dimethyl L-tartrate as the starting material (30% overall yield). The system 2,3-dideoxy-L-threo-hex-2-enono-1,5-lactone is present in several natural compounds.

An orthoquinone isolated from Salvia aethiopis

Abstract A new orthonaphthoquinone diterpene has been isolated from Salvia aethiopis and given the trivial name aethiopinone. The structure of this natural

Stereoselective synthesis of substituted exo-glycals from 1-exo-methylene pyranoses

Halo-exo-glycals of the gluco-, manno- and galacto- series, readily prepared by reaction of 1-exo-methylene pyranoses with iodonium dicollidinium triflate (IDCT), undergo Suzuki or B-alkyl Suzuki cross-coupling reactions with boronic acids or alkyl boranes to yield, in a stereoselective manner, functionalized exo-glycals.

The synthesis of D-asperlin

The synthesis of the D-enantiomer of asperlin has been carried out. The stereochemistry of the epoxide ring has been assigned as 6R,7S for this D-enantiomer.

13C NMR substituent effects in tetracyclic diterpenoids

Abstract The 13 C NMR chemical shifts of ent -beyer-15-ene, and one hydroxy and four acetoxy derivatives are reported. The substituent effects of the acetoxy groups upon the saturated and olefinic carbon atoms are discussed. Conformational aspects of the molecules are considered in the light of these effects.

Diterpenoids from Salvia oxyodon and Salvia lavandulifolia

Abstract Three new diterpenoids have been detected in Salvia oxyodon and identified as 3β-hydroxy-dehydroabietic acid, 3β-acetoxy-abieta-8(14)-en-18-oic acid 9α,13α-endoperoxide and 3β-hydroxy-abieta-8(14)-en-18-oic acid 9α,13α-endoperoxide. Salvia lavandulifolia yielded two known compounds ursolic acid and galdosol.

Regio- and enantioselective esterifications of polyoxygenated compounds catalyzed by lipases

Abstract The lipase catalyzed esterifications of derivatives of propane-1,2,3-triol and butane-1,2,4-triol in organic solvents have been studied. The influence of several factors (lipase source, organic solvent, additives and structural variations in the substrates) on the selectivity have been investigated. Good levels of regio- and enantioselectivity have been achieved, providing practical methods for the synthesis of these chiral building blocks.