Recent Advances in Azaborine Chemistry

Abstract

The chemistry of organoboron compounds has been primarily dominated by their use as powerful reagents in synthetic organic chemistry. Recently, the incorporation of boron as part of a functional target structure has emerged as a useful way to generate diversity in organic compounds. A commonly applied strategy is the replacement of a CC unit with its isoelectronic BN unit. In particular, the BN/CC isosterism of the ubiquitous arene motif has undergone a renaissance in the past decade. The parent molecule of the 1,2-dihydro-1,2-azaborine family has now been isolated. New mono- and polycyclic BN heterocycles have been synthesized for potential use in biomedical and materials science applications. This review is a tribute to Dewar's first synthesis of a monocyclic 1,2-dihydro-1,2-azaborine 50 years ago and discusses recent advances in the synthesis and characterization of carbon(C)-boron(B)-nitrogen(N)-containing heterocycles.

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

“…Due to integration of the boron's empty p z orbital into the π-system of the molecule, these molecules often display substantially different photophysical/chemical properties compared to their carbon congeners such as intense blue to green luminescence (λ em = 400-491 nm, Φ Fl.~5 0-70%) and tunable redox properties [59]. 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].…”

Accelerating the Understanding and Development of Hydrogen Storage Materials: A Review of the Five-Year Efforts of the Three DOE Hydrogen Storage Materials Centers of Excellence

“…[94,95] The premise here is that in these carbon-boron-nitrogen heterocycles (see the bottom of Figure 17 for an example of a CBN), the exothermic release of hydrogen from the BN segment of a molecule can be coupled to and offset the endothermic release of hydrogen from the CC segment of the same molecule. If the kinetics of release can be made to be similar for the two channels, then the thermodynamics of hydrogen release may be coupled, resulting in principle in a nearthermoneutral release material.…”

Metall‐vermittelte Synthese von 1,4‐Di‐tert‐butyl‐1,4‐azaborin

“…[2] Der formale Austausch einer C-C-Doppelbindung in Benzol gegen eine isoelektronische und isostrukturelle B-N-Bindung führt zu 1,2-Azaborinen, zu denen es noch zwei weitere Strukturisomere gibt. Quantenchemische Rechnungen sagen vorher, dass die thermodynamische Stabilität dieser Isomere in der Reihe 1,2 > 1,4 > 1,3 abnimmt.…”

“…Quantenchemische Rechnungen sagen vorher, dass die thermodynamische Stabilität dieser Isomere in der Reihe 1,2 > 1,4 > 1,3 abnimmt. [3] Die Chemie substituierter 1,2-Azaborine ist bereits seit den 1960er Jahren gut untersucht, und es wurden zahlreiche mono-und polycyclische Derivate [2] synthetisiert, und auch in den letzten Jahren gab es noch bemerkenswerte Beiträge, vor allem von Liu et al, die von der Synthese und Isolierung der Stammverbindung 1,2-Dihydro-1,2-azaborin berichteten. [4] Dagegen blieb das 1,3-Azaborin bis vor Kurzem, wahrscheinlich wegen seiner niedrigen thermodynamischen Stabilität, unbekannt.…”