Synthese stereoselective d'une composante de la pheromone sexuelle de “l'ecaille rouge de californie”: l'acetate d'isopropenyl-6 methyl-3 decadiene-3,9 yle (3Z,6R)

Chemistry of the pheromones of mealybug and scale insects

“…63 The second route achieved excellent control over the alkene geometry, but at the cost of a considerably longer route (Scheme 26). 68 Thus, reaction between aldehyde 177 and silylimine 179 (generated in 4 steps from 1,4-butanediol in 63% yield) followed by hydrolysis gave a,b-unsaturated aldehyde 180 in an 87 : 13 ratio favoring the desired (E)-isomer, and the undesired (Z)-isomer was cleanly isomerized to the (E)-isomer by treatment of the mixture with pyridinium hydrochloride. Aer reduction of the aldehyde to the corresponding alcohol 181, the synthesis was completed by one of two sequences in similar yields, i.e., reductive removal of the benzyl protecting group, selective conversion of the allylic alcohol of 182 to the chloride, reduction of the chloride to the methyl group, and acetylation, or conversion of the allylic alcohol to a sulfate leaving group, reduction to the methyl, and simultaneous removal of the benzyl protecting group and acetylation with acetic anhydride with perchloric acid catalysis (not shown).…”

Simple Porphyrin Desymmetrization: 5,10,15,20‐Tetrakis(3‐hydroxyphenyl)porphyrin (mTHPP) as a Gateway Molecule for Peripheral Functionalization

“…We then hoped that by using a stronger base, it would be possible to reduce the amount of higher order substituted products in the crude reaction mixture and, therefore, drive the production of monofunctionalized material and ease the purification workload. Examples of this have been reported with regard to alkyl diol compounds, which would normally give a statistical mixture of isomers during attempts to obtain the monofunctionalized product 13. The dianionic species that is formed when NaH is used as the base showed a statistical bias towards the functionalization of only one hydroxy group in approximately 90 %.…”

First total synthesis of (+)-indicanone

“…The simple retrosynthesis of (+)-1 afforded the reasonable tactics described in Scheme 1. The vinyl phosphate moiety of the known diene 2, 7 derived from (+)-limonene, would be converted into the propargyl alcohol derivative 3, which should be a precursor of the allenyl functional group in the latter stage. The acetal group of 3 would be transformed into the propyne derivative 4 by a conventional procedure.…”