The scope and limitations of the ring-opening of thiophene dioxides upon reaction with cyclic secondaryamines, leading to dialkylaminomethyl substituted halobutadienes has been further studied. Using ω-unsaturated acyclic secondaryamines trienes could be prepared by this methodology.
NHC‐supported 1,2‐dithienyldiborenes was synthesized from the corresponding (dihalo)thienylborane NHC precursors. NMR and UV/Vis spectroscopic data, as well as X‐ray crystallographic analyses, were used to assess the electronic and steric influences on the B=B double bond of various NHCs and electron‐donating substituents on the thienyl ligands. Crystallographicdata showed that the degree of coplanarity of the