A deprotonation pathway to reactive [B]CH boraalkenes.

The BH compounds IMes(Ar)BH(NTf) (Ar: CF or FpXyl) were converted to the IMes(Ar)BCH boraalkenes in a three step reaction sequence of B-methylation with methyllithium, hydride abstraction and deprotonation. The BCH boraalkenes reacted with elemental sulfur to give a thiaborirane product. They underwent [2+2] cycloaddition reactions with carbon dioxide or sulfur dioxide to give four-membered boron containing heterocycles. The boraalkenes added strongly Lewis acidic boranes at their CH carbon atoms. The corresponding HB(CF)/boraalkene adduct reduced carbon monoxide to a -OCH(CF)- moiety inside a five-membered heterocycle at the B-CH-B template. The boraalkenes reacted with the [(MeS)AuCl] reagent to form the corresponding (boraalkene)AuCl complexes.