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1st July 2014 @ 17:01


The previous reaction Synthesis of 3-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-4-methylbenzenesulfonamide (PT-1-20-2) was repeated on a 1/3 scale with the purified product from Resynthesis of 3-bromo-4-methyl-benzenesulfonamide (PT-17-3).

3-bromo-4-methylbenzenesulfonamide (93 mg, 0.372 mmol), bis(pinacolato)diboron (142 mg, 0.559 mmol, 1.5 eq), potassium acetate (147 mg, 1.5 mmol, 4eq) was dissolved in 1,4-dioxan (2 mL) and degassed with argon for ten minutes. Pd(dppf)2.CH2Cl2 (15 mg, 17 umol, 5 mol%) was added and the reaction heated to 100°C in a sealed tube for 16 hours. TLC and NMR indicated one major product consistent with reported literature for the title compound. The reaction was diluted with methanol/dichloromethane (20 mL, 1:1), filtered through celite, and evaporated directly onto silica, then purified by dry column vacuum chromatography (0-50% ethyl acetate in heptane, 10 fractions)[1] to give the title compound as a waxy white solid (93 mg, 76% pure, MW 297, 0.238 mmol, 64%). 1H NMR consistent with literature. Taken on as-is due to time constraints.



 

 Notes:

[1] The product co-elutes closely with starting material and the last few fractions that eluted were discarded.

 

NMR:

PT-20-3-C1 1H NMR CDCL3.pdf

Compound integrated 12.5:10 for boronate to pinacol, corresponding to a molar purity of 55% and a mass purity of 76%

 

Literature: 

http://www.sciencedirect.com/science/article/pii/S0960894X10014587

 

 

InChI:

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Attached Files
PT-20-3-C1 1H NMR CDCL3.pdf
CJCOSDD_ptm203c1cdcl3_020714_1H_pr500.tar