Virginie Prat

Synthèses Stéréosélectives des Acides 13 E et 13 Z Rétinoı̈ques via un Nouvel Intermédiaire β-Méthylènealdéhyde en C-15

Resume The methylene-de-oxo-bisubstitution reaction between dimethyl isopropylidene malonate and the C-15 β-methylenealdehyde 1 which could serve as substitute for E β-ionylideneacetaldehyde 2, produces stereoselectively the E,E olefin. Hence, new stereoselective syntheses of 13 E and 13 Z retinoic acids were described.

SYNTHESIS, STRUCTURE AND REACTIVITY OF ACETYLENIC CO2(CO)6 PYRYLIUM SALTS.ELECTRONIC INFLUENCE OF THE CO2(CO)6 ACETYLENIC FRAGMENT

Abstract The formation of new pyrylium salts bearing in the γ position an acetylenic Co2(CO)6 fragment is described. X-ray analysis showed that the γ carbon of the pyrylium ring does not interact with a cobalt atom. However, IR values, relating to the carbonyl stretching band, suggested that a part of the positive charge is delocalized on the cluster core. Finally, the reactivity of these cationic complexes towards nucleophiles is reported.

Stereoselective synthesis of 13Z retinoic acids via β-methylenealdehydes as synthons

Abstract A stereoselective synthesis of 13Z retinoic acids via β-methylenealdehydes is described. In methylene-de-oxo-bisubstitution reactions (Knoevenagel, Stobbe, etc.), these new synthons produce stereoselectively E olefins. Hence, a synthesis of 13Z retinoic acids is described, via a stereospecific monodecarboxylation of carboxy-14-retinoic acids.

New Synthetic Analogs of Retinoids: Synthesis of Aromatic Analogs of 9-Methylidene- and 13-Demethyl-9-methylidene-retinol, -retinal, and Ethyl 13-Demethyl-9-methylideneretinoate

Aromatic analogs of 9-methylidene and 13-demethyl-9-methylideneretinol, -retinal, and ethyl 13-demethyl-9-methylideneretinoate were synthesized via a new β-methylidene-aldehyde synthon.

Syntheses of new 9- and 13-methylene isomers of retinal

Abstract Syntheses of new 9- and 13-methylene isomers of retinal via the ‘9-methylene-C-18 ketone’ 1 or ‘C-18 ketone’ 2 are reported.

SYNTHESIS OF NEW γ- AND δ-LACTONES BY ACID CYCLIZATION OF 2,4-DIETHYLENIC-DIACIDS

We have developed an easy synthesis for new γ- and δ-lactones. Acid-catalyzed cyclization of 2,4-diethylenic-diacids yields new γ or δ-lactones, depending on the substitution pattern of the unsaturated side chain.

Synthesis of 9‐Methylene Analogs of Retinol, Retinal, Retinonitrile and Retinoic Acid

Retinoids, 9-methylene analogs of retinol, retinal, retinonitrile and retinoic acid, were synthesised from a new synthon β-methylenealdehyde.

Synthesis of new ethyl 9-methylene-13E and 13Z-retinoates via the Julia olefination reaction

Abstract Synthesis of new ethyl 9-methylene-13 E and 13 Z -retinoates via the 9-methylene C-15 sulphone 5 is reported. The Julia olefination strategy was used for building the C-20 skeleton.

STEREOSELECTIVE SYNTHESIS OF 9-METHYLENE-13-DEMETHYL ANALOGS OF NATURAL RETINOIDS

9-Methylene-13-demethyl analogs of retinol, retinal and retinoic acid, methyl ester were synthesised via new synthons β-methylenealdehydes.