Novel reactivities of 2,2-dichloroimidazolidine-4,5-diones: synthesis of copper(I) diamidocarbene complex, 2-thioxo/selenoxoimidazolidine-4,5-dione, and 2,2-difluoroimidazolidine-4,5-dione

A new method for the in situ generation of five-membered diamidocarbenes (DACs 2) from 2,2-dichloroimidazolidine-4,5-diones is established by Cl/I exchange and elimination of iodine. The trapping of 2 with CuI, S, and Se provides a good route for the preparation of a dimeric (2a)CuI complex and 2-thioxo/selenoxoimidazolidine-4,5-diones, respectively. In contrast, Cl/F exchange is explored to yield exclusively 2,2-difluoroimidazolidine-4,5-diones.