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. 2024 Sep 11;146(36):24748-24753.
doi: 10.1021/jacs.4c08088. Epub 2024 Jul 31.

A BN-Benzvalene

Tomoya Ozaki  1 , Sierra K Bentley  1 , Nina Rybansky  1 , Bo Li  1 , Shih-Yuan Liu  1
Affiliations

A BN-Benzvalene

Tomoya Ozaki et al. J Am Chem Soc. .

Abstract

The synthesis and crystallographic characterization of BN-benzvalene, the first second-row heteroatom-containing benzvalene, is described. BN-benzvalenes are produced via photoexcitation of C5-aryl-substituted 1,2-azaborines under flow conditions. Mechanistic studies support a boron-specific, two-step photoisomerization pathway involving a BN-Dewar benzene intermediate, which is distinct from the photoisomerization pathway proposed in benzene and phospha- and silabenzenes for the formation of their respective benzvalene analogues.

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Conflict of interest statement

Notes

The authors declare no competing financial interest.

Figures

Figure 1.
Figure 1.
1H NMR spectra in CDCl3 of C5-p-Tol-BN-Dewar benzene 3a (top trace) and p-Tol-BN-benzvalene 2a (bottom trace) in CDCl3. Arene signals above 6.5 ppm are not shown.
Figure 2.
Figure 2.
Crystal structures of 2o and 1o (hydrogen atoms have been omitted for the sake of clarity). Thermal ellipsoids are drawn at the 50% probability level. Selected bond lengths in Å for 2o are N–B = 1.419(3), N–C6 = 1.479(3), B–C4 = 1.575(3), C4–C3 = 1.531(3), C4–C5 = 1.546(3), C6–C3 = 1.494(3), C6–C5 = 1.497(3); Selected bond lengths in Å for 1o are N–B = 1.446(3), N–C6 = 1.388(2), B–C3 = 1.519(3), C3–C4 = 1.355(3), C4–C5 = 1.421(3), C6–C5 = 1.355(3).
Scheme 1.
Scheme 1.
Main Group Heteroatom-Containing Benzvalenes
Scheme 2.
Scheme 2.
Initial Discovery
Scheme 3.
Scheme 3.
Synthesis of BN-Bicyclo[2.1.1]hexane
Scheme 4.
Scheme 4.
Mechanistic Studies
Scheme 5.
Scheme 5.
Proposed Mechanism for Formation of BN-Benzvalene
See this image and copyright information in PMC

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