Benzenesulfonic acid, 4-methyl-, compd. with pyridine (1:1) → p-Toluenesulfonic acid

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Reaction Steps

1-Amino-5-methyltetrazole (71 mg, 0.72 mmol) and pyridinium para-toluenesulfonate (6 mg, 0.024 mmol) were dissolved in absolute ethanol (10 ml) and heated to reflux for 15 minutes. Compound 37(f) (0.17 g, 0.41 mmol) in ethanol (6 ml) was added dropwise to the solution. The reaction was stirred at reflux for 3 hours, and then cooled to room temperature overnight. The solvent was removed in vacuo and diluted with t-butyl methyl ether to provide the tosic acid salt, which was isolated by filtration and dried in vacuo. This solid was treated with sodium bicarbonate (20 rug) in water (6 to 7 ml) and ethyl acetate to form the free base. The layers were separated, and the aqueous layer was extracted with ethyl acetate. The combined organics were dried over MgSO4, filtered, and concentrated by rotary evaporation to provide 0.12 g of the desired product.

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