Desaurin
Desaurins are a type of sulfur-containing heterocycle. The parent is 2,4-bismethylene-1,3-dithietane. They are derived from the base-promoted condensation of carbon disulfide with "active methylene" compounds:
According to X-ray crystallography, the C4S2 core of desaurins is planar. With unsymmetrical substitution, they can exist as separable cis and trans isomers.