合成路线1

The reaction of 3-methyl-3-buten-1-ol (I) with tosyl chloride and DMAP in dichloromethane gives the corresponding tosylate (II), which is condensed with tetrakis tetrabutylammonium pyrophosphate (III) in acetonitrile and purified through Dowex 50-WXB-200 (NH4+), yielding the corresponding ester (IV) as an ammonium salt. Finally, this compound is brominated with Br2 in water and purified through Dowex 50-WXB-200 (Na+) to afford the target compound. The intermediate tetrakis tetrabutylammonium pyrophosphate (III) has been obtained as follows: Disodium pyrophosphate (V) is deionized by means of Dowex 50-WXB-200 (H+) to give pyrophosphoric acid (VI), which is then neutralized with tetrabutylammonium hydroxide in water affording the target pyrophosphate (III).