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Dimerization of salicyladehydes provided 6H,12H-6,12-epoxydibenzo[b,f][1,5]
dioxocins in multigram quantities. Deprotonation-allylation of the benzylic
acetals followed by further functionalization of the diallyl derivative an
d double Friedel-Crafts cyclization gave a novel preussomerin analogue whic
h possessed the full carbon skeleton of the natural products.