Uses
Geranyl bromide is used for the preparation of 3,7-dihydroxyflavone derivatives and baicalein. It is also involved in the synthesis of potential flavonoidic modulators of P-glycoprotein activity. Further, it reacts with benzenesulfinic acid to prepare geranyl phenyl sulfone. In addition to this, it takes part in the palladium catalyzed cross coupling with aryl and alkenylgold(I) phosphanes.
Synthesis
General procedure for the synthesis of (E)-1-bromo-3,7-dimethylocta-2,6-diene from geraniol: Geraniol (10 g, 11.4 mL, 64.8 mmol, 1.0 eq.) was dissolved in dichloromethane (50 mL) under nitrogen protection. The solution was cooled to -20°C. A solution of phosphorus tribromide (3.0 mL, 32.4 mmol, 0.5 eq.) in dichloromethane (10 mL) was added slowly dropwise, keeping the reaction temperature below -16°C. The color of the solution changed to green/blue during the dropwise addition. The reaction mixture was stirred for 3 hours at about -20°C. Subsequently, water (50 mL) was carefully added at -40°C. The aqueous layer was extracted with ether (3 x 50 mL). The organic layers were combined and washed sequentially with saturated aqueous sodium bicarbonate (3 x 50 mL) and aqueous ammonium chloride, dried over anhydrous sodium sulfate, and concentrated under reduced pressure to give a brown oily product (14.5 g, 66.6 mmol, quantitative yield).
References
[1] Journal of the American Chemical Society, 1990, vol. 112, # 13, p. 5276 - 5290
[2] Synthesis, 1984, # 10, p. 876 - 881
[3] Bulletin of the Chemical Society of Japan, 1981, vol. 54, # 5, p. 1456 - 1459
[4] Journal of the American Chemical Society, 2006, vol. 128, # 43, p. 14012 - 14013
[5] Advanced Synthesis and Catalysis, 2008, vol. 350, # 3, p. 365 - 369
