Hydrochloric Acid → Dimethyl 2-methyl-1-(tosylamino)-5-(3-methyl-2-pyrazinyl)pyrrole-3,4-dicarboxylate

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Reaction Steps

0.81 g of sodium was heated with 20 ml of methanol, then a solution of 6.8 g of 31A in 20 ml of methanol was added and the mixture was stirred at room temperature for 1 hour. Then a solution of 11.2 g of 7B in 25 ml of THF was added, and the mixture was stirred at room temperature for 2 hours. The mixture was stripped of volatiles, 100 ml of methanol was added to the residue and hydrogen chloride gas was bubbled through the mixture, which then was heated at reflux for 2 hours. The mixture was cooled, neutralized with a saturated aqueous solution of sodium bicarbonate and extracted with methylene chloride. The extract was stripped of volatiles, and the residue was triturated with 10 ml of ether. The solid product was collected and dried (Na2SO4) to give dimethyl 2-methyl-1-(tosylamino)-5-(3-methyl-2-pyrazinyl)pyrrole-3,4-dicarboxylate (31C), as a light yellow solid, m.p.: 177°-178° C.

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