Sulfur-nitrogen heterocycles from the condensation of pyrazolones and 2-iminothiazolidin-4-ones with phenyl isothiocyanate

The condensation of 2-pyrazolin-5-ones with phenyl isothiocyanate, followed by reaction of the resulting thiolate ions with chloroacetyl chloride, phenacyl bromide, oxalyl chloride, 1,4-dibromo-2,3-butanedione and ethyl chloroformate, resulted in cyclisation to S,N-heterocycles in all cases. 2-lminothiazolidin-4-ones, with phenyl isothiocyanate and then chloroacetyl chloride or phenacyl bromide, similarly formed 2,4'-bi(thiazolidine)-derived products.