NEW MATERIAL:The titled compound of formulaI(R1 is H, alkyl, acyl; R2 is H, alkyl, aralkyl).

EXAMPLE: 1,2,3,7,8,8a-Hexahydro-1-acetoxy-7-methyl-8-( 3'-benzyloxy )propylnaphthalene.

USE: Synthetic intermediate of ML-236B, a cholesterol synthesis inhibitor, and of a variety of organic compounds.

PREPARATION: 1,2-Dibromoethane and 1-bromo-3-(1'-ethoxy)ethoxypropane are subjected to 3-stage reactions to give a compound of formula III and the product is converted into its methyl ester. Then, dimethyl phosphonate, subsequently 4- benzyloxybutylaldehyde are made to react with the methyl ester, followed by cyclization to give trans-octalone of formula IV. The compound of formula IV is reduced, acetylated and deprotected to give a compound of formula V. The exemplified compound of formula II is obtained therefrom.