Evodone (23). To a suspension of 5 mg (0.05 mmol) of hydroquinone in 20 mL of freshly distilled ethylbenzene in a 25-mL, round-bottomed flask was added 60 mg (0.30 mmol) of acetylenic ketone 22. The resulting solution was refluxed in the absence of light and under an atmosphere of dry N2 for a period of 96 h.The ethylbenzene was then removed under reduced pressure to afford ~70 mg of a dark brown oil. Thick-layer chromatography (40% acetone/petroleum ether, R¡ 0.65) of this material afforded 39 mg (76%) of 23 as a colorless crystalline solid. Recrystallization from MeOH/H20 gave colorless needles, which after sublimation (0.015 mmHg, 25 °C) had a melting point of 70-71 °C (lit.7 mp 73 °C):
Base‐induced cycloadditions of tosylmethyl isocyanide to a series of isothiocyanates have been investigated. Depending on the reaction conditions, thiazoles 5 and/or imidazoles 7 are obtained, with the thiazoles, in particular, being obtained with high regiospecificity. During the course of this work a high‐yield ring transformation of 5‐amino‐1,3‐thiazoles (5) to imidazole‐5‐thiols (7) was discovered, which has not been previously reported. A number of reactions of 7 are described.
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