Potassium Carbonate → (4-Oxazol-5-yl-naphthalen-1-yl)-carbamic acid tert-butyl ester

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Reaction Steps

The above mixture of compounds 503A & 503B (3.37 g, 10.0 mmol; corrected for presence of compound 503A), toluene-sulfonylisocyanide (2.15 g, 11.0 mmol) and potassium carbonate (1.66 g, 12.0 mmol) in 50 mL of methanol was refluxed for 4 h. The reaction mixture was partitioned between water (200 mL) and chloroform (200 mL). After extracting the aqueous layer with chloroform (100 mL), the combined organic layers were dried over magnesium sulfate and concentrated in vacuo. The crude residue was purified by flash chromatography on silica gel eluting with a gradient of 10–40% ethyl acetate in hexane to give 1,35 g (44%) of compound 503C as a white solid. 1HNMR (400 MHz, DMSO-d6): δ 9.45 (s, 1H), 8.57 (s, 1H), 8.20 (m, 2H), 7.76 (m, 2H), 7.64 (s, 1H), 7.62 (m, 2H), 1.51 (s, 9H).

Provenance & Evidence