Isothiazole 5-lithio

Isothiazoles undergo metallation at C-5, provided this position is unsubstituted. 4-Methyl-5-lithio-isothiazole is obtained by reaction with butyl-lithium in dry THF at - 70 °C. On further treatment with sulphur, it yields solutions of lithium isothiazole-5-thiolates (32). Although unstable to air, these salts are convertible in situ into 5-alkylthio-isothiazoles, e.g. (33), with alkylating agents. Alternatively,... 

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