T. Cuvigny

Syntheses with sulfones XLIX : stereo- and enantioselective synthesis of (s)-(-)-3,9-dimethyl 6-(1-methylethyl) (e)-5,8-decadien 1-ol acetate, sexual pheromone of yellow scale.

Abstract The stereo- and enantioselective synthesis of the yellow scale pheromone, (S)-(-)-3,9-dimethyl 6-(1-methylethyl) (E)-5,8-decadien 1-ol acetate, from 3-(R) ( +)-valerolactone 5 and [(4-methyl 3-pentenyl) sulfonyl] benzene 8 is described. The key step is the introduction of the isopropyl group by the stereoselective cross-coupling reaction of the dienesulfone 12 with isopropylmagnesium chloride in the presence of FeCl3.

Etude de la regioselectivite de la substitution des carbanions par des derives allyliques catalysee au palladium. Obtention selective de composes a carbone quaternaire

Abstract The influence of the leaving groups, carbanions and ligands on π-allylpalladium has been investigated in the substitution of primary or tertiary terpene derivatives. Conditions have been found under which the substitution takes place essentially at one or the other end of the allylic system. This provides a new and convenient way to obtain compounds with quaternary carbon atoms, which has been exemplified by the synthesis of 3,3-dimethyl-4-pentenenitrile.

Asymmetric alkylation of chiral N,N-disubstituted amides

Abstract Chiral N,N -disubstituted amides may be readily synthesized by reacting an anhydride with l - or d -ephedrine. The alkylation of the carbanions derived from these amides affords α-substituted chiral ketones and acids after cleavage. A study of the reaction characteristics indicates that the nature of the counter ion (Li or Mg) is the critical factor in the asymmetric synthesis. In this way, ( S )-(+)-4-methyl-3-heptanone, an alarm pheromone of “Atta Texana”, was synthesized in 81% enantiomeric excess.

Syntheses with sulfones. XLVI: Stereoselective preparation of 2-benzenesulfonyl-1,3-dienes and 2-benzenesulfonyl-1,4-dienes

Abstract The stereoselective syntheses of EE 2-benzenesulfonyl-1,3-dienes and 2-benzenesulfonyl-1,4-dienes are described. Diels-Alder cycloaddition of the EE 2-benzenesulfonyl-1,3-dienes 3b with methylvinyketone is reported.

Substitutions catalysees au nickel d'acetates et de sulfones allyliques

Abstract The allylic substitution of stable enolates derived from diethyl malonate, ethyl cyanoacetate, ethyl benzylsulfonylacetate, bis(benzenesulfonyl)methane and sodium p -toluenesulfinate by a variety of allylic esters and sulfones have been investigated. Suitable ligands and reaction conditions have been found to ensure high yields, and in some cases considerable control of the regioselectivity of the reaction.

Syntheses with sulfones XLVII : stereoselective access to 1,3- and 1,4-dienes through hydrogenolysis of benzenesulfonyldienes. Application to pheromone synthesis

Abstract The stereospecific reduction of EE 2-benzenesulfonyl-1,3-dienes to ZE 1,3-dienes with Grignard reagents under transition metal catalysis ie described, Hydrogenolysis of the sulfonyl moiety of 2-benzenesulfonyl-1,4-dienes to ZE 1,4-dienes with sodium dithionite ie reported. These techniques have been applied to the stereoselective synthesis of (7E, 9Z) dodecadienyl acetate 3d , (9Z, 11E)tetradecadienyl acetate 3e and (9Z, 12E) tetradeoadienyl acetate, 6b .

Syntheses with sulfones XLVIII : stereoselective synthesis of 2-isopropyl 1,4-dienes through the iron-catalysed cross-coupling reaction of 2-benzenesulfonyl 1,4-dienes and isopropylmagnesium chloride

Abstract The stereoselective synthesis of 2-isopropyl 1,4-dienes through the cross-coupling reaction of 2-benseneaulfonyl 1,4-diene e and isopropylmagnesium chloride under transition-metal catalysis is described. Iron salts, which were better catalysis than palladium or nickel ones, led to substitution, of the sulfonyl group with > 97% stereospecifcity and without isomerisation of the isopropyl Grignard moiety to the n-propyl derivative. Notable amounts of the compound resulting from reduction of the sulfonyl group were also formed.

Synthesis with sulfones (noXXXI) : The stereospecific reduction of 2-benzenesulfonyl-1,3 dienes to conjugated Z,E-dienes. Synthesis of (9Z,11E)-9,11-tetradecadienyl acetate.

The stereospecific reduction of 2-phenylsulfonyl-1,3-dienes li to conjugated EZ dienes 2 catalysed by transition metal complexes in the presence of n-butyl magnesium chloride is described. This method is illustrated by the synthesis of the pheromone of Spodoptera littoralis : 9Z,11E-tetradecadien-1 yl acetate 8,R=Ac.

Synthesis with sulfones (noXXX) : Stereoselective synthesis of arenesulfonyl-1,3-dienes.

Abstract Basic treatment of allylic 1,1-disulfones gives 1-arenesulfonyl 1,3-dienes, Condensation of aldehydes with lithiated allylic sulfones and in situ acetylation of the alkoride thus formed followed by basic elimination of acetic acid leads to EE 2-arenesulfonyl 1,3-dienes. Good to very good stereoselectivity can be achieved.

Alkylations allyliques catalysees au nickel

Abstract Stable enolates such as diethyl malonate enolate can be smoothly substituted by allylic acetates (or sulfones) in the presence of nickel complexes. Sulfinate ions convert allylic acetates into sulfones.