The chemistry of terpenes. Part XVIII. Synthesis of methyl (–)-cis-chrysanthemate and of a methyl (+)-cis-homochrysanthemate from (+)-car-3- and -2-ene

Abstract

Methyl (–)-cis-chrysanthemate (7) has been synthesised from methyl (+)-cis-2,2-dimethyl-3-(2-oxopropyl)-cyclopropanecarboxylate (12) obtained in a series of steps from (+)-car-3-ene. Methyl (+)-cis-homochrysanthemate [methyl (+)-cis-2,2-dimethyl-3-(3-methylbut-2-enyl)cyclopropanecarboxylate](16) was prepared from methyl (+)-cis-2,2-dimethyl-3-(3-oxobutyl)cyclopropanecarboxylate (14) obtained from (+)-car-2-ene. (+)-4α-Tosyloxymethylcar-2-ene (5) is reduced with lithium aluminium hydride to a mixture of (+)-4α-methyl-car-2-ene (4) and (+)-1,4,4-trimethyl-cis-transoid-1,3-cis-tricyclo[5.1.0.0.^3,5]octane (21).