Synthesis
A hexane solution (100 ml, 164 mmol) of 1.6 M n-butyllithium was added slowly and dropwise to an ice bath solution of N-tert-butylbenzenesulfonamide (15.92 g, 74.7 mmol) in N-tert-butylbenzenesulfonamide (200 ml) over 30 min. The reaction mixture was kept in a clarified state. Subsequently, triisopropyl borate (24.1 ml, 104 mmol) was added dropwise under ice bath conditions. The reaction mixture was stirred at room temperature for 3.5 h. The solution was observed to become gradually turbid. After completion of the reaction, the mixture was cooled in an ice bath and 1N hydrochloric acid (200 ml) was added slowly. The mixture was stirred at room temperature overnight. The reaction solution was extracted with ether (2 x 50 ml). The combined organic phases were washed with 1N sodium hydroxide (2 x 60 ml). The aqueous phase was adjusted to pH=1 with 6N hydrochloric acid and extracted again with ether (2×100 ml). The combined ether extracts were dried with anhydrous magnesium sulfate and concentrated under reduced pressure to remove the solvent. The crude product was recrystallized by a solvent mixture of ether and hexane to give 2-(tert-butylamino)sulfonylphenylboronic acid as a white solid (11.5 g, 60% yield). es-MS (M + H)+ = 258.
References
[1] Patent: US6673817, 2004, B1. Location in patent: Page column 200
[2] Patent: EP874629, 2004, B1. Location in patent: Page/Page column 15-16
[3] Bioorganic and Medicinal Chemistry Letters, 2001, vol. 11, # 22, p. 2947 - 2950
[4] Bioorganic and Medicinal Chemistry Letters, 2002, vol. 12, # 12, p. 1651 - 1655
[5] Bioorganic and Medicinal Chemistry, 2008, vol. 16, # 14, p. 6841 - 6849
