Phosphorus oxychloride → Imidazo[5,1-b]oxazole, 2-phenyl-

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Reaction Steps

To 0.6 g (3 mmol) (2) in 15 ml toluene was added dropwise 1 ml phosphorus oxychloride and the resulting solution was heated at 90° overnight. Then, the solvent was removed in vacuo and the residue carefully diluted with 50 ml water. This solution was made basic with 40% NaOH solution and extracted with 4×50 ml portions of methylenechloride. The combined organic extracts were washed with brine, dried and the solvent removed in vacuo to give a dark gum. This was purified by chromatography on silica gel eluting with methylene chloride (97%)-isopropanol (3%) to give pure (3) as a waxy, tan solid, m.p. 128°-131° (dec).

Provenance & Evidence