Yield:-

Reaction Conditions:

Stage #1: C₁₃H₁₉BrO₃with n-butyllithium in diethyl ether;hexane at -78; for 0.666667 h;
Stage #2: with triethyl borate in diethyl ether;hexane at -78; for 4.16667 h;
Stage #3: with hydrogenchloride;water in diethyl ether;hexane at 20; for 17.5 h;Heating / reflux;

Steps:

This was dissolved in diethyl ether (10 mL) and cooled to -78°C under N₂. H-BuLi (3.0 mL, 4.80 mmol, 1.6 M in hexanes) was added dropwise via syringe over 10 minutes and the reaction mixture stirred 30 minutes at -78°C. Triethylborate (2.95 mL, 10.9 mmol) was added as a solution in diethyl ether (5 mL) dropwise via syringe over 10 minutes, then stirring at -78°C was continued for 4 h. 6 M HCl (1.3 mL) was added, the reaction warmed to RT, stirred 16 h then heated to reflux 1.5 h. The reaction was then cooled (0°C) and basified with 4 M NaOH to pH 14. The layers were separated and the organic layer washed with 2 M NaOH (2 x 20 mL); the aqueous phases were then combined and washed with TBME (2 x 40 mL). The aqueous layer was cooled to 0°C and acidified with 2 M HCl to pH 1. The resultant precipitate was isolated by filtration to give the title compound.Yield: 306 mg (36%). LC/MS t_r 1.05 min. MS(ES+) m/z 195 (M+H).

References:

WO2007/89669,2007,A2 Location in patent:Page/Page column 118