Hydrochloric Acid → 5,7-Dichlorothiazolo[4,5-d]pyrimidin-2(3H)-one

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Reaction Conditions

Reaction Steps

A suspension of the trichloro compound (22: 3.0 g, 12 mmol) in 1N NaOH (35 mL) was heated at 60° C. for 1 h. The solution was treated with decolorizing carbon and then acidified with 10% aqueous HCl. The resulting precipitate was collected and reprecipitated from dilute base with glacial acetic acid to provide 24 as orange needles (1.38g, 50%): mp. 191°-192° C.: UV λmax (pH 1) 254 nm (ε 5,300), 290 (11,400): UV λmax (pH 7,11) 226 nm (ε 28,900), 300 (14,100). Anal. Calcd. for C5HCl2N3OS: C, 27.04: H, 0.45: C1, 31.93: N, 18.93. Found: C, 26.78: H, 0.61: C1, 32.15: N, 18.66. Single crystal X-ray analysis of 24 showed the structure assignment to be correct.

Provenance & Evidence