Boraindenes serve as versatile precursors for accessing structurally diverse benzannulated boron heterocycles, complementing those derived from monocyclic boroles and tricyclic 9-borafluorene analogues.
We report the synthesis of 1,2,3-triphenyl-1-boraindene, the second known example of a singly benzene-fused borole, and highlight its distinct properties and reactivity compared to non-fused and doubly benzene-fused borole derivatives.
DFT calculations predict endocyclic CO insertion in 1,2,5-azadiborolidines followed by dimerization and double [1,2]-migration, defining a fourth class of metal-free CO-inserting boracycles.
Boroles react with a nucleophilic silylene to give silylium ylides or bicyclic sila-borabicyclo[2.1.1]hex-2-ene. Reduction either affords clusters of Si(II) or a donor-supported silavinylidene, which can be subsequently converted into the former.
While free borabenzene maintains its aromaticity due to its π sextet, the fusion with 3D aromatic o-carborane disrupts this aromatic character.