nones are obtained when β-benzoylpropionamides are heated with thionylchloride. Somereactions of 5-benzoyl-2-phenyl-3-isothiazolinone are described, the most interesting being that with dimethyl and diethyl malonate carbanions, in which ring opening, loss of sulphur, and subsequent ring closure occur, leading to maleimide derivatives.
N-Substituted isothiazol-3(2H)-ones can be easily prepared fromN-substituted 3-benzoylpropi-onamides in two experimentally simple steps, in satisfactory overall yields. Reaction of the amides with excess thionylchloride results in the formation of N-substituted 5-benzoylisothiazol-3(2H)-ones, which are readily debenzoylated with alkali to the corresponding N-substituted isothiazol-3(2H)-ones. This