(±)-trans-Homochrysanthemic acid, m.p. 80-80.5°, is obtained by the Arndt-Eistert reaction of (±)-trans-chrysanthemoyl chloride with diazomethane and the structure of the resulting homoacid is confirmed by ozonolysis to give acetone and (±)-trans-homocaronic acid. (±)-cis-Chrysanthemoyl chloride, when undergoing the same reaction sequence, gives (±)-cis-3-isobutenyl-2, 2-dimethylcyclobutane-1-carboxylic acid, bp. 104-5°/2mm., which is demonstrated by ozonolysis to give acetone and cis-norpinic acid. Both (±)-trans-homochrysanthemic and (±)-cis-3-isobutenyl-2, 2-dimethyl-cyclobutane-1-carboxylic acids are readily converted by boiling with dilute sulphuric acid into the same δ-Iactone. This lactone is theoretically deduced to be δ, δ-dimethyl-γ-isobutenyl-δ-valerolactone and is also confirmed by ozonolysis to give acetone and δ, δ-dimethyl-γ-carboxy-δ-valerolactone, m. p. 175°

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