NEW MATERIAL:An ascofuranone analog of formula I (R1 is oxo, lower alkylenedioxy; R2 is 2-tetrahydropyranyloxy, hydroxyl, lower alkanoyloxy, halogen, formula II: where when R2 represents oxy group, R2 must not be the group of formula III).

EXAMPLE: 5-[ 1,5-Dimethyl-7-( 2-tetrahydropyrany )oxy-1E,5E-heptadienyl]-dihydro- 2,2-dimethyl-3(2H)-furanone(1a).

USE: It is used as a synthetic intermediate of (±)-ascofuranone, which is used as a preventive or remedy for arteriosclerosis and a carcinostatic agent, because of its antihyperlipemic and antitumor activities.

PREPARATION: The condensate resulting from reaction between the compound of formula IV and another compound of formula V, is allowed to react with an orthoformic acid alkyl ester in the presence of a catalyst in an inert solvent to give the compound formula VI among compounds of formula I .