Abstract Oxalylation of 3-oxo-N-phenyl-3-R-propanethioamides in aprotic solvents in the temperature range from− 40° C to+ 20° C results in 4-acyl-5-phenylamino-2, 3- dihydrothiophene-2, 3-diones and 2-(2-oxo-2-R-ethylidene)-3-phenyl-1, 3-thiazolidine-4, 5- diones, while in the presence of potassium carbonate, potassium 4-acyl-2, 3-dioxo-1-phenyl- 2, 3-dihydro-1 H-pyrrole-5-thiolates are formed.
