A deprotonation pathway to reactive [B]CH ₂ boraalkenes

Abstract

The BH compounds IMes(Ar ^F)BH(NTf ₂) (Ar ^F: C ₆F ₅ or FpXyl) were converted to the IMes(Ar ^F)BCH ₂ boraalkenes in a three step reaction sequence of B-methylation with methyllithium, hydride abstraction and deprotonation.

Abstract

The BH compounds IMes(Ar ^F)BH(NTf ₂) (Ar ^F: C ₆F ₅ or FpXyl) were converted to the IMes(Ar ^F)BCH ₂ boraalkenes in a three step reaction sequence of B-methylation with methyllithium, hydride abstraction and deprotonation. The BCH ₂ 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 ₂ carbon atoms. The corresponding HB(C ₆F ₅) ₂/boraalkene adduct reduced carbon monoxide to a –OCH(C ₆F ₅)– moiety inside a five-membered heterocycle at the B–CH ₂–B template. The boraalkenes reacted with the [(Me ₂S)AuCl] reagent to form the corresponding (boraalkene)AuCl complexes.