Simple, one-step syntheses of tri- and tetracyclic B,N,S-heterocycles from reactions of a diboracumulene with thiols

Abstract

Boron-containing fused heterocycles have received considerable attention due to their unique structures, bonding, and intriguing properties. However, progress in this area has been hampered by a lack of efficient synthetic methodologies. In this study, we demonstrate the reactivity of a diboracumulene, LBBL (L = cyclic (alkyl)(amino)carbene, CAAC), with various nitrogen-containing heterocyclic thiols. These straightforward reactions result in the partial or complete cleavage of the B–B multiple bonds in the diboracumulene, along with S–H bond activation in the thiol units, leading to the formation of a range of tricyclic and tetracyclic B,N,S-heterocycles. Notably, the tricyclic B,N,S-heterocycle exhibits π aromaticity in all three of its rings.