IIb-e in conventional steps to the salt IIf. Decomposition of IIf under vacuum at 90-120" led to a complex mixture of isomers from which the four major products could be isolated by preparative gas-liquid partition chromatography. These are, in order of elution from a 3.5-m, 10% Carbowax 20M on 45-60 Chromosorb P column operated at 100" with a helium flow of 100 cc/min, tropilidene (19%; relative retention time 1.00), bicyclo [5.2. 0] nona-2, 4, 8- ...