Triisopropyl borate → Boronic acid, B-(2-(((1,1-dimethylethyl)amino)sulfonyl)phenyl)-

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Reaction Steps

To (tert-butyl)(phenylsulfonyl)amine (17.43 g, 81.83 mmol) in 180 ml dry THF in an ice bath was added nBuLi (66 ml, 2.5M in hexanes) via addition funnel. Then triisopropyl borate (33 ml, 143.06 mmol) was added via addition funnel. The mixture was warmed to room temperature and allowed to stir for 4 hr. The reaction mixture was then cooled in an ice bath before HCL (82 ml, 3M) was added dropwise. This was allowed to stir at room temperature for 3 hr. The mixture was then put in the freezer over the weekend. The reaction was then warmed to room temperature and extracted with ether. The aqueous layers were washed twice more with ether. The combined organic layers were washed three times with 5M NaOH aqueous solution. The combined basic layers were acidified to pH=1 with 6M HCL solution. These acidified layers were then extracted three times with ether. These ether layers were then dried over MgSO4, filtered, then concentrated in vacuo to about 50 ml solution. To this solution was added hexanes and a minimal amount of ethyl acetate. A white precipitate is observed and the mixture in stored in the freezer to allow for crystallization. The white solid is then filtered and collected (14.65 g, 57 mml, 70%) ES-MS(M+H)+=258.

Provenance & Evidence