Metalationof 1-Phenyland 1-Methylpyrazole 6271 6-o-Carboxyphenylthiopurine (Method D).-A mixture of 5.35 g. (38.8 mmoles) of anhydrous potassium carbonate and 3.30 g. of o-mercaptobenzoic acid (Eastman technical grade) in 20 ml. of dimethylformamide was stirred mechanically for 5 minutes. 6-Chloropurine (3.00 g., 19.4 mmoles) then was added, and when no temperature rise occurred during 15 minutes of vigorous stirring, the mixture was heated at 40-50°in a warm water-bath for an hour. The resulting thin suspension was poured into 120 ml. of water, and the clear solution was partially neutralized with 5 ml. of concentrated hydrochloric acid. The pH now was adjusted to 3 with 1 N hydrochloric acid. The tan solid that precipitated was collected by filtration, washed thoroughly with water and dried in vacuo over phosphorus pentoxide at 61°; yield 5.15 g. (97.5%), m.p. 235-237°. This material was twice precipitated from 1 N sodium hydroxide solution with 1 N hydrochloric acid; recovery, 4.12 g. of light tan solid, m.p. 238-239°. 9-B enzy 1-6-b enzylthiopurine.-a-Chiorotoluene (0.12 ml., 1.03 mmoles) was added to a well-stirred mixture of 250 mg. (1.03 mmoles) of 9-benzyl-6-mercaptopurine,u 137 mg. (1.03 mmoles) of anhydrous potassium carbonate and 3 ml. of dimethylformamide. The mixture was stirred at room temperature (23-25°) for 15 minutes and then heated between 40 and 53°for about 30 minutes. Then the mixture was cooled and poured into 25 ml. of water: a tan solid precipitated. The resulting mixture (pH 8-9) was cooled in an ice-water-bath and the solid was collected, washed with water and dried in vacuo over phosphorus pentoxide at room temperature; yield 308 mg. of a tan powder (90%), m.p. 108°with softening from 102°. Recrystallization of ca. 295 mg. from ca. 20 ml. of cyclohexane gave 240 mg. of matted white needles after drying in vacuo at room temperature; m.p., needles fused at 100°f orming a solid that melted at 108°; spectral data: Xml in m/i (« X 10_3):
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