Trimethyl borate → [3-[5-[N-[(2-methylpropan-2-yl)oxycarbonyl]carbamimidoyl]-2-methylsulfanylthiophen-3-yl]sulfonylphenyl]boronic acid

Participants

Reaction Conditions

Reaction Steps

A solution of 2M i-PrMgCl in THF (1.1 mL, 2.2 mmol) was added dropwise at 0° C. to {[4-(3-bromo-benzenesulfonyl)-5-methylsulfanyl-thiophen-2-yl]-imino-methyl}-carbamic acid tert-butyl ester (0.5 g, 1.0 mmol) (Example 27c) in 5.0 mL THF. The solution was stirred for 20 mins at 0° C., then cooled to −78° C. and a solution of 2.5 M n-BuLi in hexanes (0.6 mL, 1.5 mmol) was added. The mixture was stirred for 5 mins then trimethylborate (0.35 mL, 3.3 mmol) was added at −78° C. and the mixture allowed to attain RT. The reaction was quenched with sat. NH4Cl (10 mL) and extracted with EtOAc (3×20 mL), dried over Na2SO4 and evaporated. The crude solid was purified by elution from a 5 g SPE with 10% MeOH/DCM to give 0.45 g (95%) of the title compound as a yellow solid: 1H NMR (400 MHz, CD3OD) δ 8.28 (m, 1H), 8.05 (m, 1H), 7.95 (m, 1H), 7.60 (m, 2H), 2.66 (s, 3H), 1.51 (s, 9H). Mass spectrum (ESI, m/z) calcd. for C17H21BN2O6S3 456.1, found 456.7 (M+H).

Provenance & Evidence