Trimethyl borate → tert-butyl N-[4-[3-[2-(hydroxymethyl)-6-methylphenyl]phenyl]sulfonyl-5-methylsulfanylthiophene-2-carboximidoyl]carbamate

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Reaction Steps

n-Butyllithium (2.5M) [4.03 mL] was added to a solution of (2-iodo-3-methyl-phenyl)-methanol (1.00 g, 4.04 mL) [example 213, step a] in ether [20 mL] at −78° C. and stirred for 0.5 hours. Trimethyl borate [1.13 mL, 10.1 mmol) was added and the solution was stirred for 2 hours at room temperature, followed by evaporation. The crude residue was dissolved in ethanol/toluene (1/2) [30 mL] and 2M sodium carbonate [16.2 mL] followed by addition of {[4-(3-bromo-benzenesulfonyl)-5-methylsulfanyl-thiophen-2-yl]-imino-methyl}-carbamic acid tert-butyl ester (0.49 g, 1.01 mmol) [example 27, step c]. The solution was bubbled with argon and then tetrakis(triphenylphosphine)palladium(0) (0.18 g, 0.15 mmol) was added. The reaction was refluxed for 3 hours and then cooled to room temperature. Ethyl acetate was added and the crude reaction was washed with brine, dried over magnesium sulfate and evaporated. Column chromatography (50% EtOAc in hexanes) of the residue yielded the title compound (0.40 g, 74%) as a solid. ESI-MS (m/z): Calcd. for C25H28N2O5S3: 532.12; found: 532.7.

Provenance & Evidence