Jacques Viala

Convenient Conversion of cis-Homoallylic Alcohols into Corresponding Bromides with Ph3PBr2

Abstract An mild and easy worked up procedure using the cheap reagent Ph3PBr2 allowed us to improve the conversion of sensitive alcohols (homoallylic and acetalized) into their corresponding bromides in high yields.

Total synthesis of 4(RS)-F4t-isoprostane methyl ester

Abstract The first total synthesis of 4( RS )-F 4t -isoprostane methyl ester 1 is described using diacetone- d -glucose as starting material. This new isoprostane (neuroprostane) would be very useful in neurological studies as a potent lipid peroxidation index to obtain an integrated assessment of oxidative stress in the human brain.

Total stereospecific synthesis of all cis-5,8,11,14,17-eicosapentaenoic acid (EPA)

Abstract Total stereospecific synthesis of EPA has been performed by a sequence of ozonolysis, selective reduction and Wittig reactions which affords the cis -skipped olefinic system. Versatile Compound 4 , readily prepared from dihydro anisole allowed us to prepare the skipped dienic synthon 2 in high yield.

A new facile preparation of a bifunctionalized C6 homologating agent from 1,4-cyclohexadiene

Abstract a new preparation of the bifunctionalized unsaturated C6 homologating agent 2b which is an efficient synthetic tool is described. This method is atom economic, very efficient on grams scale and easy to handle from cheap commercially available 1,4-cyclohexadiene. Synthetic applications by using a mild and selective monohydrolysis of acetal catalysed by FeCl 3 are described.

A convergent strategy toward linear cis-skipped polyenes

Abstract An easy preparation of symmetric Cis-skipped polyenic hydrocarbons 1 to 5 combining the controlled classical Wittig reaction or the oxidative dimerization of phosphoranes is described.

C3-homologation. Synthesis of C19-skipped polyenic pheromones

Abstract Total synthesis of three sex pheromone components including an all-cis diene or triene unit are described. Starting from decanal, cis-Wittig reactions, by using C3 homologating agent 4 and convenient phosphonium salts, allowed us to built up all-cis skipped polyenic skeleton of the targets. These syntheses are shorter than those described in the literature and have been performed in better overall yield from starting materials.

Chiral conformationally restricted arachidonic acid analogs based on a 1,3-dioxane core

Abstract Chiral building blocks derived from l -diethyl tartrate are derivatized into various chiral arachidonic acid analogs based on a dioxane core.

Synthesis of (11R,17S)-11,17-dimethylhentriacontane: a communication pheromone of ant Camponotus vagus

Abstract The convergent synthesis in high enantiomeric and diastereoisomeric purity of (11R,17S)-11,17-dimethylhentriacontane, a communication pheromone of ant Camponotus vagus is described. The stereogenic centres were introduced from commercially available (R)-citronellol and (R)-citronellal.

Chemical shifts of ethylenic carbons in polyunsaturated fatty acids and related compounds

The 13C NMR of ethylenic carbon atoms in the methylene‐interrupted cis double bonds as found in polyunsaturated fatty acids (PUFAs), their precursors and analogs was studied. The chemical shifts of unsaturated carbon atoms are strongly dependent on a combination of electric field effects from the head group, steric hindrance and the presence of other double bonds. A full set of shift parameters were determined based on a reference value given by a long aliphatic alkene (cis‐6‐dodecene at 129.99 ppm) and various functionalities (double bond, ester, aldehyde, acetal, hydroxyl methyl, etc.) with one, two and three double bonds. Application of shift parameters to polyfunctionalized polyenes, high PUFAs and new analogs of arachidonic acids shows that the method is a convenient way to predict the chemical shift of all ethylenic carbon atoms.

NEW C6 FUNCTIONALIZED ACETYLENIC SYNTHETIC TOOL

ABSTRACT We describe an efficient and very easy two-step preparation of a new C6 acetylenic homologating agent 4. This compound is a precursor of 1,4-enyne and 1,3-eneallene units which are useful building blocks for the total synthesis of modified PUFAs.