The State of the Art in Azaborine Chemistry: New Synthetic Methods and Applications

Abstract

Boron-nitrogen heteroarenes hold great promise for practical application in many areas of chemistry. Enduring interest in realizing this potential has in turn driven perennial innovation with respect to these compounds' synthesis. This Perspective discusses in detail the most recent advances in methods pertaining to the preparation of BN-isosteres of benzene, naphthalene, and their derivatives. Additional focus is placed on the progress enabled by these syntheses toward functional utility of such BN-heterocycles in biochemistry and pharmacology, materials science, and transition-metal-based catalysis. The prospects for future research efforts in these and related fields are also assessed.

Control of Excited‐State Conformations in B,N‐Acenes

“…Similar considerations can be made for one of the smallest possible nitrogen‐containing compounds with such a property, aminoborane (H 2 N−BH 2 ; Figure ). The B−N scaffold has been discussed as C=C surrogate because of its isoelectronic character . However, it has been shown early on that the B−N rotational barrier (29.3 kcal mol −1 ) of aminoborane is much smaller than that of the C=C bond in ethylene (62.5 kcal mol −1 ) .…”

“…In the excited state, the conformation resulting from a 90° rotation around the B−N bond is not the lowest in energy, though. Further relaxation by pyramidalization is more favored owing to negative hyperconjugation resulting in a twisted out‐of‐plane arrangement of the amine . Based on this, we designed a system that would allow favoring an electronic transition to one specific conformer in the excited state (Figure ).…”

Isomerization and rearrangement of boriranes: from chemical rarities to functional materials

“…On the other hand, heterocyclic scaffolds that contain N, B, and either S or O, are virtually unknown, with the closest relatives being aza- [60], thia- [61], and oxaborinines [62]. This type of isosterism in aromatic systems has garnered increasing attention due to the potential use of these B,N-or B,Xembedded aromatics in optoelectronic materials and medicinal science [63].…”

B2N2‐Embedded Polycyclic Aromatic Hydrocarbons with Furan and Thiophene Derivatives Functionalized in Crossed Directions

“…Although BN‐containing systems have received considerable attention, more fundamental studies of the BN‐embedded PAHs are required, such as conjugation, aromatic/antiaromatic, chemical and photophysical properties. Therefore, investigation of the relationship between the chemical structures of the BN‐embedded PAHs and the related properties remains challenging …”