5‐Arylidene‐2‐thiazolidinone‐4‐thiones 1 undergo Michael type reactions with Ω‐nitrostyrene, α,β‐unsaturated ketones and N‐arylmaleimides to give the corresponding 7‐aryl‐tetrahydro‐7H‐thiopyrano[2,3‐d]thiazole‐2‐one derivatives 3 and 4. Arylmagnesium bromides add to the lateral double bond of 5‐arylidene‐3‐phenyl‐2‐thiazolidinone‐4‐thiones 5 to yield products 6. With phenyl‐hydrazine at room temperature, 1 or 5 yield the corresponding aldehyde phenylhydrazones and 4‐phenyl‐hydrazono‐2‐thiazolidinone or its 3‐phenyl derivative. The thione group in 5‐diaryl‐methyl‐2‐thiazolidinone‐4‐thiones condenses with phenylhydrazine to yield 5‐diarylmethyl‐4‐phenyl‐hydrazono‐2‐thiazolidinones 9.

Treatment of 5‐arylideneisorhodanines 1 with GRIGNARD reagents, effects addition of the reagent to the double bound of the lateral chain to yield products, proved to have structure 2. The thiono group in 1 and 2 condenses with aniline to yield the corresponding 5‐substituted‐4‐phenylimino‐2‐thiazolidinones 3 and 4. Alkylation of 1 and 2 with alkyl halides or with ethereal diazomethane results in the formation of the S‐alkyl derivatives 5 and 6, respectively.

Treatment of 5‐arylidene‐2‐thiazolidinone‐4‐thiones 1 with diazomethane in etherchloroform mixture effects N‐methylation beside S‐methylation to give the products 2 and 3 respectively. The S‐alkylated derivatives 2 and 4 are obtained exclusively by the treatment of 1 with ethereal diazomethane or with ethyl bromoacetate, respectively. The N‐piperidinomethyl and N‐morphilinomethyl derivatives 5 were obtained by the MANNICH reaction on 1. The reaction of 1 with acrylonitrile or ethylacrylate in pyridine medium at room temperature yields the products 6. Subjecting 5‐arylazo‐2‐thiazolidinone‐4‐thiones 7 to the action of ethereal diazomethan gives both the S‐ and N‐methylated derivatives 8 and 9, respectively. Subjecting 5‐arylazo‐4‐methylmercapto‐3‐thiazolin‐2‐ones 8 to the action of aniline yields 5‐arylazo‐4‐phenylimino‐2‐thiazolidinones 10.

Aus Grignard‐Reaktionen der Isorhodanine (I) hervorgegangene Titelverbindungen, wie z.B. die (II), bilden, ebenso wie die (I) selbst, Anile, wie z.B. die (III).

Bei Behandlung der Thiazolidinonthione (I) mit Diazomethan in Äther/Chloroform werden die S‐ (II) und N‐Methylderivate (III) erhalten, in reinem Äther dagegen ausschließlich die S‐Methyl‐isomeren (II).