Convenient Method for the Synthesis of Lineatin, a Pheromone Component of Trypodendron lineatum

Article abstract of DOI:10.1021/jo00010a033

Synthesis of racemic lineatin (1), a pheromone component of Trypodendron lineatum, is described.Condensation of 5-methyl-5-hexen-2-one (2) and triethyl phosphonoacetate with LiN(SiMe3)2 gave esters 3, which upon hydrolysis gave acids 4a-f.The bicyclo<3.2.0> ring compounds 5 and 6 were obtained via an intramolecular <2+2> addition by refluxing underivatized carboxylic acids 4a-f with NaOAc and Ac2O.Compound 5 was isomerized to the thermodynamically more stable isomer 6 using a Pd/C catalyst activated with hydrogen.Reduction of 6 with LiAlH4 gave the endo and exo isomers 7a and 7b (4:1).Isolation of the alcohol 7a followed by acetylation gave 8.Subsequent oxidation with OsO4 and methylmorpholine N-oxide gave diol 9.Cleavage of 9 with H5IO6 in diethyl ether gave keto aldehyde 10, which was converted to keto acetal 11.Treatment of 11 with MeMgBr followed by acidic workup gave 1.The overall efficiency is ca. 20percent.