José Coll

Synthesis of dienic fluorinated analogs of insect sex pheromones

Abstract Synthesis of fluorinated analogs of some dienic insect sex pherormones through a stereocontrolled Wittig reaction of β-fluorinated aldehydes with the appropriate ω-functionalized ylides is reported. Some features of the 1H and 19F NMR spectra of these analogs are also discussed.

Insect antifeedant activity of clerodane diterpenoids against larvae ofSpodoptera Littoralis (Boisd.) (Lepidoptera)

Antifeedant activities of nine clerodane diterpenoids, isolated in this laboratory from different species ofAjuga plants, have been studied against larvae of Egyptian cotton leafwormSpodoptera littoralis (Boisd.) (Lepidoptera) by application of the leaf disk method. Evaluation of activity was carried out by calculating, at different time intervals, the feeding ratio (FR) from the relationship between the consumed areas of treated disks (CTD) and control disks (CCD); for comparison purposes a FR50 defined as the FR at a CCD of 50% was established. Some compounds exhibited activity at a 0.01 μg/cm2 dose (0.3 ppm). Structure-activity relationships are discussed

Regiospecific reduction of unsaturated conjugated ketones with sodium dithionite under phase transfer catalysis

Abstract Selective double bond reduction of unsaturated conjugated ketones has been achieved in excellent yields by use of sodium dithionite in a two phase benzene-water system with Adogen as phase transfer catalyst. However, this reduction was unsatisfactory for hydrophilic ketones; in this case, competitive reactions led to the predominant formation of water soluble sulfur derivatives, similar to those obtained in the reaction of unsaturated conjugated ketones with sodium dithionite in aqueous dimethylformamide.

Clerodane diterpenoids from Teucrium and Ajuga plants

Abstract A new clerodane diterpenoid, chamaepitin has been isolated from Ajuga chamaepitys. The previously known clerodanes, 19-acetylgnaphalin, auropolin, teucrin A and teuflin, have been isolated from Teucrium species (T. polium subsp. belion, T. polium subsp. capitatum and T. asiaticum) collected in Majorca. X-ray diffraction analysis on crystals of auropolin has allowed the assignment of configuration at C-20 as S for this compound.

Neo-clerodane diterpenoids from Ajuga chamaepitys

Abstract From the whole plant of Ajuga chamaepitys , 15-ethoxy-14-hydroajugapitin and a C-15 epimeric mixture of 14-hydro-15-hydroxyajugapitin have been isolated.

Neo-clerodane diterpenoids from Ajuga pseudoiva

Abstract From the whole plant of Ajuga pseudoiva two epimeric neo -clerodane diterpenoids, 2-acetylivain I and its C-2 epimer 14,15-dihydro-ajugapitin, have been isolated. The structures were established by spectroscopic and chemical means. 2-Acetylivain I had not been previously reported, while its C-2 epimer had been isolated from Ajuga chamaepitys .

Simple and stereoselective synthesis of sex pheromone of processionary mothThaumetopoea pityocampa (Denis and Schiff.)

A simple and stereoselective synthesis of (Z)-13-hexadecen-11-yn-1-yl acetate, the major component of the sex pheromone ofThaumetopoea pityocampa (Denis and Schiff.) is described. The procedure essentially involves formylation of a terminal acetylene to the corresponding aldehyde followed by a stereochemically controlled Wittig reaction, which has been studied under a variety of conditions.

Initial field trials with the synthetic sex pheromone of the processionary mothThaumetopoea pityocampa (Denis and Schiff.)

Synthetic (Z)-13-hexadecen-11-ynyl acetate has been shown to be highly active in catchingThaumetopoea pityocampa (Denis and Schiff.) males in field trials carried out in different parts of Spain. A variety of formulations containing antioxidants or solid paraffin were tested. Formulations containing 3 and 10% ofE isomer showed a decrease of activity compared with those prepared with pureZ isomer. Dodecyl acetate, also found in the virgin female gland, did not show any synergistic effect when tested in a 9∶1 mixture with the synthetic pheromone. The product exhibited a remarkable persistence of activity under the field conditions even in the absence of stabilizer.

Synthesis of 25-fluoroponasterone A, a fluorinated analogue of 20-hdyroxyecdysone.

Abstract Very precise reaction conditions, using mild fluorination procedures combined with acetonide deprotection, were developed for preparation of 25-fluoroponasterone A from 20-hydroxyecdysone. Biological activity of the new compound was examined and the possible relationship between structure and biological activity in ecdysteroids was studied using MMP2 calculations of the conformations of the side chain of three related compounds: ecdysone, 20-hydroxyecdysone and 25-fluoroponasterone A.

Phytoecdysteroid analysis by high-performance liquid chromatography-thermospray mass spectrometry

The potential of high-performance liquid chromatography-mass spectrometry with thermospray interface to identify and analyse ecdysteroids has been investigated. The response of eight different ecdysteroids and their acetonide derivatives is studied by positive- and negative-ion detection as well as with single-ion monitoring and scan mass detection modes. The usefulness of this technique for ecdysteroid identification and quantitation is discussed and, finally, the identification of a new phytoecdysteroid isolated from Polypodium vulgare is presented as an application of this technology. A fast and easy procedure for the extraction and purification of phytoecdysteroids is also described.