Terpenoids. Part LXX. Synthesis of $(\pm)$-7,8- and -5,6-dimethyl-2-(2-hydroxyisopropyl)tetralins, stress metabolites from tobacco mosaic virus infested tobacco

Two stress metabolites I $(R=CMe_2OH, R_1=R_2=H, R_3=R_4=Me; R= CMe_2OH, R_1=R_2=Me, R_3=R_4=H)$ produced by tobacco leaves inoculated with tobacco mosaic virus were prepared from the tetrahydronaphthoates I $(R=CO_2Me, R_1=R_2=H, R_3=R_4=Me; R=CO_2Me, R_1=R_3=Me, R_3=R_4=H)$, elaborated in turn from 2,3-dimethylbenzaldehyde and 4-(2,3-dimethylphenyl)butanoic acid, respectively