NEW MATERIAL:A warburganal analog expressed by formulaI(X is H or OH; Y is formyl or acetal thereof; R' is H or lower alkyl).

EXAMPLE: ( 1R, 4aS, 5S, 8aR )-1,2,3,4,4a,5,8,8a-Octahydro-5, 6-diformyl-1,4a-dimethyl-5-hydroxy-1-naphthalenecarboxylic acid.

USE: A feeding inhibitor for armyworm, antitumor agent and anticancer agent.

PROCESS: A novel compound expressed by formula II (Y' is acetalized formyl; R" is lower alkyl) is reacted with a strong base, e.g. n-butyl lithium, to convert the -CH2CHO into an enolic salt, which is then reacted with trimethylsilyl chloride and subjected to the ozonolysis to afford a compound expressed by formulaI-a. The resultant compound expressed by formulaI-a is then reacted with a strong base and treated with an oxidizing agent to give a compound expressed by formulaI-b, which is then hydrolyzed to afford a compound expressed by formulaI-c.