Cyclonona-1, 2, 5-triene (13a) and 7-methoxycyclonona-1, 2, 5-triene (13b) have been prepared in satisfactory yields by the action of MeLi on (12a) and (12b), respectively; cyclodeca-1, 2, 5, 6-tetraene (29) has similar been prepared from 16. Cyclonona-1, 2, 5-7- tetraene (22), which was prepared from 20 at below− 40°, readily dimerizes to give 21; the half-time of the reaction is 10–20 min in CDCl3 solution at 0°.