From bromoesters with silver

By the employment of other bromides O-desmethylmycophenolic acid was obtained. Thus, the C7 bromoester methyl 6-bromo-4-methylhex-4-enoate, BrCH2CH=C(Me)CH2CH2C02Me, was prepared from tritylgeraniol which was first converted in several steps to the terminal diol, Malaprade oxidation of which furnished 4-methy-6-trityloxylhex-4-enal. Mild oxidation to, the corresponding acid with silver oxide, formation of the methyl ester with diazomethane and derivation of the required allylic bromide by treatment of the alcohol, liberated from the trityl derivative, with carbon tetrabromide containing triphenylphosphine completed the synthesis. 

Ref 2), later from the 2-bromo ester and silver nitrate in acetonitrile (Ref 3),. by oxidizing 1-nitropopatrfe-l with nitric acid followed by esterification (Ref 4), by reacting silver nitro-form with the 2-bromoester (Ref 5) and by reacting the 2-bromo or iodoester with nitric acid (Ref 6)... 

---