Metal‐Mediated Synthesis of 1,4‐Di‐tert‐butyl‐1,4‐azaborine

Abstract

Completing the set: Although 1,2‐azaborine is known, little is known about the 1,3‐ and 1,4‐analogues. Now a simple, controlled synthesis of 1,2‐di‐tert‐butyl‐1,2‐azaborine from acetylene and di‐tert‐butyliminoborane has been achieved by a metal‐mediated formal [2+2+2] cycloaddition reaction. A 1,2‐azaborete pianostool complex was identified as an reaction intermediate.

Synthesis and Hydroboration of a Mixed‐Donor Iminoboryl Complex of Platinum

“…After a long period of inactivity, research interest in the synthetic possibilities of iminoboranes has recently been reignited with our discovery that cycloadditions of iminoboranes with two alkyne units can be effected in the presence of a rhodium catalyst, leading to either 1,2-or 1,4-azaborinines, isosteres of benzene. [2] More recently still, studies by Bertrand, Stephan and ourselves have uncovered stable Lewis acid-base adducts of carbenes with iminoboranes. [3] Transition metal iminoboryl complexes (L n MBϵNR, II and III; Figure 1), discovered in 2006 in our laboratories, are essentially transition metal derivatives of iminoboranes, containinganM-Bsinglebond.…”

Formation of Azaborines by Photoelimination of B,N‐Heterocyclic Compounds

“…[5] Among p-conjugated organoboron compounds, azaborine molecules or BÀN-containing aromatic molecules have attracted much research interest and efforts. [6] The replacement of a C À C unit in an aromatic molecule with an isoelectronic B À N unit has been shown to impart interesting electronic, photophysical, luminescent, and chemical properties, which are often very distinct from those of the CÀC-containing aromatic analogues, to the molecule. [6] This observation has led to many potential applications of BÀN-containing aromatic compounds, such as hydrogen storage materials, [7] optoelectronic materials, [8] sensors, [9] and bioactive molecules.…”

“…[6] The replacement of a C À C unit in an aromatic molecule with an isoelectronic B À N unit has been shown to impart interesting electronic, photophysical, luminescent, and chemical properties, which are often very distinct from those of the CÀC-containing aromatic analogues, to the molecule. [6] This observation has led to many potential applications of BÀN-containing aromatic compounds, such as hydrogen storage materials, [7] optoelectronic materials, [8] sensors, [9] and bioactive molecules. [10] Nonetheless, examples of polycyclic pconjugated azaborine molecules and derivatives remain rare compared to the vast number of CÀC-containing aromatic compounds and heterocyclic aromatic compounds.…”

“…The syntheses of azaborine compounds are in general very challenging and often involve multi-step reactions or the use of transition-metal catalysts. [6] Thus, the development of efficient and simple synthetic methods for BÀN-containing aromatic compounds is highly important to advance the chemistry and applications of this important class of compounds.…”

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

“…Supporting information for this article is available on the WWW under http://www.angewandte.org or from the author. isosteres of benzene (i.e., 1,2-dihydrido-1,2-azaborine, [2] 1,3-dihydrido-1,3-azaborine, and 1,4-dihydrido-1,4-azaborine; [3] see Scheme 1), 1,3-dihydro-1,3-azaborine (from hereon abbreviated as 1,3-azaborine) is thermodynamically the least stable isomer. [4] Not surprisingly, its development has lagged the other azaborines in the series.…”