TRANS,TRANS-FARNESYL BROMIDE

• S-trans, trans-farnesyl-L-cysteine methylester, a post translational modified amino acid
• umbelliprenin, starting reagent for the synthesis of (±)-farnesiferol A and (±)-farnesiferol C
• prenylated peptides

Trans,trans-farnesyl bromide was prepared as follows: phosphorus tribromide (0.95 mL, 10.25 mmol) was added dropwise over a few minutes to a stirred solution of trans,trans-farnesyl alcohol 3 (6.9 g, 31.08 mmol) in ether (80 mL) at 0 C. The reaction mixture was stirred at 0C for an additional 1 hour. The reaction was quenched with water (5 mL), the ether was removed under reduced pressure and the resulting slurry was suspended in water (100 mL). The aqueous slurry was extracted with hexane (3× 150 mL), dried with anhydrous Na2SO4, and the solvent was evaporated to give the desired bromide trans,trans-farnesyl bromide, Yield: 8.7 g (crude product); TLCRf: 0.93 (n-hexane solution of 10% EtOAc).