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1st July 2014 @ 17:01
The previous reaction [blog=10193]Synthesis of 3-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-4-methylbenzenesulfonamide (PT-1-20-2)[/blog] was repeated on a 1/3 scale with the purified product from [blog=10214](PT-17-3)[/blog]. 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: [data]12203[/data] Compound integrated 12.5:10 for boronate to pinacol, corresponding to a molar purity of 55% and a mass purity of 76%   Literature:     InChI:
Attached Files
PT-20-3-C1 1H NMR CDCL3.pdf