Phosphorus oxybromide → HCID 21417208, compound

Participants

Reaction Steps

A mixture of 10.6 parts of 2-(4-chlorophenyl)-3-hydroxy-2,4,6,7-tetrahydro-thiopyrano[4,3-c]pyrazole, prepared according to the method of Example 1, and 12 parts of phosphorous oxybromide in 120 parts of xylene was refluxed for 7 hours and then stirred at room temperature for 12 hours. The suspension was neutralized with 5% sodium bicarbonate followed by extraction with chloroform (3 × 100 parts). The chloroform solution was washed with a saturated NaCl solution, dried over anhydrous magnesium sulfate and evaporated at a reduced pressure of 50 to 300 mm Hg, yielding a brown oil. This oil crystallized from acetone yielding 4.3 parts of the desired product, m.p. 138°-145° C.; a second recrystallization from acetone/methylene chloride gave 3.4 parts of pure 3-bromo-2-(4-chlorophenyl)-2,4,6,7-tetrahydrothiopyrano[4,3-c]pyrazole, m.p. 143.5°-145° C.

Provenance & Evidence