Implications of the final ring closure to 10b-aza-10c-borapyrene for aryl–alkyne ring-closing mechanisms

Abstract

Through a combined computational and isotopic labeling study, it has been observed that the activation energy for the aryl–alkyne ring closure of the azaborine containing 4-ethynyl-4a-aza-4b-boraphenanthrene is dramatically lower, and it appears to proceed via an alternate mechanism than that of its hydrocarbon analog. This catalyst-free reaction proceeds at modest reaction conditions compared with traditional pyrolytic synthetic methods and holds promise for the efficient construction of fused ring systems containing azaborine functional groups that may not be accessible in the purely hydrocarbon form.

Structurally Constrained Boron-, Nitrogen-, Silicon-, and Phosphorus-Centered Polycyclic π-Conjugated Systems

“…For those who are interested, we refer to other well-summarized review articles cited herein. − , Furthermore, research based on BN-substituted PAHs was also omitted from this review since the supposedly vacant boron p orbital is rather occupied due to effective π-donation from the nitrogen atom, leading to distinctively differing properties to those of PAHs containing BC 3 units. Interested readers should refer to the pioneering work by Piers, − Pei, − Liu, Bettinger, , and Hatakeyama − as well as other associated articles − and reviews ,− for details.…”

Synthesis of Acridines through Alkyne Addition to Diarylamines

“…Study of ring closures and the packing of small molecules have bolstered the reputation and uses of grapheme [ 6 , 7 , 8 ]. Our group has focused on the ring-closure mechanisms of aromatic molecules, including the changes induced when boron and nitrogen are introduced into the carbon framework [ 9 , 10 ]. In synthesizing new precursors for study, well-known cross-coupling pathways were diverted to produce a variety of polycyclic aromatic molecules, particularly 9-substituted acridines.…”