1. Formation of derivatives of 3-nitrothiophene-2-thiol
The reaction of dipotassium 2-nitroethylene-1,1-dithiolate (III) with α-halogeno aldehydes or ketones leads to derivatives of 3-nitro-thiophene-2-thiols. These reactions proceed by an acid catalyzed cyclization of the initially formed 1-(acylmethylthio)-2-nitroethylene-1-thiolates (IV). The infrared and NMR spectra of the thiopene derivatives are discussed briefly.
Acta Chemica Scandinavica, 1970, Vol 24, Issue 7, p. 2629-2633