The three isomeric components of the San Jose scale pheromone, 5-7, have been synthesized from a common P-keto ester intermediate. A study of the alkylation of the dianion of methyl acetoacetate with a series of alkylating agents with the same carbon skeleton has been carried out. The trisubstituted alkenes in 5 and 6 have been synthesized stereospecifically via a copper-catalyzed coupling of a methyl Grignard reagent with the E or Z en01 phosphate from the alkylated P-keto ester. In the case of the Z en01 derivative, the coupling reaction was carried out on the diethyl-and diphenylphosphates, and the en01 triflate. 'The diethyl en01 phosphate gave the highest stereoselectivity. The synthetic pheromones were attractive to San Jose scale in the field.MARGOT ALDERDICE, CLAUDE SPINO et LARRY WEILER. Can. J. Chem. 71, 1955Chem. 71, (1993. Utilisant un p-ceto ester commun comme intermediaire, on a synthetise les trois isomitres 5-7 de la pheromone du pou de San JosC. On a rCalisC une Ctude de I'alkylation du dianion de 1'acCtoacetate de mCthyle par une sCrie d'agents d'alcoylation ayant le m&me squelette carbone. On a synthCtisC les alcitnes trisubstituCs 5 et 6 d'une maniitre stCreospCcifique en faisant appel a un couplage catalysC par le cuivre d'un mCthyl magnesien avec le phosphate d'Cnol E ou Z obtenu B partir du p-ceto ester alcoyle. Dans le cas du dCrivC Cnolique Z, on a rCalisC la reaction de couplage sur les phosphates Cnoliques diCthyle et de diphenyle et sur le triflate Cnolique. Le phosphate Cnolique diethylique donne la meilleure sterCosClectivitC. Dans les champs, les phCromones de synthitse attirent le pou de San Jose.[Traduit par la redaction]

No abstract

β‐Alkyl‐α,β‐unsaturated esters from enol phosphates of β‐keto esters: methyl 2‐methyl‐1‐cyclohexene‐1‐carboxylate intermediate: methyl 2‐oxocyclohexanecarboxylate intermediate: Methyl 2‐(diethylphosphoryloxy)‐1‐cyclohexene‐1‐carboxylate product: methyl 2‐methyl‐1‐cyclohexene‐1‐carboxylate byproduct: 1‐acetyl‐2‐methylcyclohexene solvent: petroleum ether

Benzeneselenenyl chloride and aluminum chloride or benzenesulphenyl chloride and silica gel initiate an electrophilic cyclization of methyl 7-methyl-3-oxo-7-octenoate to cyclohexyl derivatives. These products of the cyclization reaction have been converted into intermediates of potential use in the synthesis of unusual carotenoids.

In einer früheren Arbeit wird eine Methode zur stereoselektiven Umwandlung von β‐Ketoestern in Alkene beschrieben.