A 1,3-Dihydro-1,3-azaborine Debuts

Abstract

We present the first synthesis and characterization of a 1,3-dihydro-1,3-azaborine, a long-sought BN isostere of benzene. 1,3-Dihydro-1,3-azaborine is a stable structural motif with considerable aromatic character as evidenced by structural analysis and its reaction chemistry. Single crystal X-ray analysis indicates bonding consistent with significant electron delocalization. 1,3-Dihydro-1,3-azaborines also undergo nucleophilic substitutions at boron and electrophilic aromatic substitution reactions. In view of the versatility and impact of aromatic compounds in the biomedical field and in materials science, the present study further expands the available chemical space of arenes via BN/CC isosterism.

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.…”

Boron‐Substituted 1,3‐Dihydro‐1,3‐azaborines: Synthesis, Structure, and Evaluation of Aromaticity

“…[5] On the other hand, we showed that treatment of 1 with acetic acid readily furnished the B-OAc-substituted product. [6] Encouraged by this preliminary finding, we envisioned that 1,3-azaborine 1 could be converted to B-substituted derivatives under acidic conditions.…”

“…[4] Not surprisingly, its development has lagged the other azaborines in the series. The first synthetic example of a 1,3-azaborine debuted in late 2011, [5] and the diversity of synthetically accessible 1,3-azaborines remains very limited to date. …”

“…We already determined that heterocycle 1 did not react with a number of anionic nucleophiles due to the weak leaving group ability of the diisopropylamino group. [5] Thus, our strategy was to convert 1 into a 1,3-azaborine intermediate I bearing a good leaving group which in turn can readily undergo nucleophilic substitution (Scheme 3). With this strategy in mind, we focused our initial attention on developing B-OAc-substituted 1,3-azaborine 6 as a precursor for nucleophilic substitution reactions based on our prior success in using 6 and LiAlH 4 to produce N-Me-1,3-BN toluene.…”

“…Compound 1 is the only reported example that has been characterized by single-crystal X-ray analysis. [5] A larger structural database should facilitate the development of a better understanding of the bonding and electronic structure for this family of compounds.With a library of 1,3-azaborines now readily accessible, we have crystallographically characterized compounds 8c, 8d, and 8f. [10] 1,3-Azaborine 8f is the 1,3-BN isostere of a diphenylether (specifically, 1-methyl-3-phenoxybenzene).…”