Studies in terpenoids. Part LXIX. Synthesis of (\pm)-chrysolic acid.

(\pm)-Chrysolic acid $[I; R = CH_2CH_2C(OH)MeCH_2CO_2R_1, R_1 = H]$ was prepd. in 4 steps from I (R = H). MeCOCH_2CO_2Et was alkylated with I (R = CH2Cl), followed by deethoxycarbonylation to give I (R = CH_2CH_2COMe). Reformatsky reaction of I with $BrCH_2CO_2R_1 (R_1 = CMe_3, Me)$ gave $I [R = CH_2CH_2C(OH)MeCH_2CO_2R_1, R_1 = H, Me, resp.]$ after work up