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Synthesis of Functionalized1,3,2-Benzodiazaborole Cores Using Bench-Stable Components

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ABSTRACT

Theazaborine motif provides a unique opportunity to develop coreisosteres by inserting B–N units in place of C=C bondswithin aromatic scaffolds, creating new pseudoaromatic building blocksthat retain comparable structural features. Previous synthetic routesto the 1,3,2-benzodiazaborole core have used organoboron dichloridesand boronic acids as the boron precursors. The transformation developedherein utilizes entirely bench stable starting materials, includingorganotrifluoroborates, enabling a wider array of substrate analoguesunder facile reaction conditions. Furthermore, physical, structural,and electronic properties of these compounds were explored computationallyto understand the influence of the B–N replacement on the structure,aromaticity, and isosteric viability of these analogues.

No MeSH data available.


Indole isosteres.
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fig2: Indole isosteres.

Mentions: The indole structural motif has a demonstrated prominencein biologicaltargets,5 and therefore accessing isostericspecies would be of value for both academic and pharmaceutical applications.Currently, there are two known azaborine isosteres of indole: (i)the 1,3,2-benzodiazaborole (1), where the 2–3carbon–carbon double bond is replaced by a B–N bond,6 and (ii) the “fused” B–Nindole7 (2), in which theadjacent bond in the bicycle is exchanged (Figure 2). The indole-azaborine 1 isparticularly valuable because it provides access to an indole isosterein one step via chelation of a boron species between the amino groupsof o-phenylenediamine.8 Literature reports have revealed the incorporation of differentsubstituents on boron through the use of alkyl-,8a trialkyl-,8b and dichloroboranes9a and, in later contributions, condensation reactionswith boronic acids9b−9e or electron-deficient boronate esters.9f The major limitation of the currently available methods is the requireduse of air- and/or moisture-sensitive boron precursors that limitthe diversity within these indole isosteres.


Synthesis of Functionalized1,3,2-Benzodiazaborole Cores Using Bench-Stable Components
Indole isosteres.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4862404&req=5

fig2: Indole isosteres.
Mentions: The indole structural motif has a demonstrated prominencein biologicaltargets,5 and therefore accessing isostericspecies would be of value for both academic and pharmaceutical applications.Currently, there are two known azaborine isosteres of indole: (i)the 1,3,2-benzodiazaborole (1), where the 2–3carbon–carbon double bond is replaced by a B–N bond,6 and (ii) the “fused” B–Nindole7 (2), in which theadjacent bond in the bicycle is exchanged (Figure 2). The indole-azaborine 1 isparticularly valuable because it provides access to an indole isosterein one step via chelation of a boron species between the amino groupsof o-phenylenediamine.8 Literature reports have revealed the incorporation of differentsubstituents on boron through the use of alkyl-,8a trialkyl-,8b and dichloroboranes9a and, in later contributions, condensation reactionswith boronic acids9b−9e or electron-deficient boronate esters.9f The major limitation of the currently available methods is the requireduse of air- and/or moisture-sensitive boron precursors that limitthe diversity within these indole isosteres.

View Article: PubMed Central - PubMed

ABSTRACT

Theazaborine motif provides a unique opportunity to develop coreisosteres by inserting B–N units in place of C=C bondswithin aromatic scaffolds, creating new pseudoaromatic building blocksthat retain comparable structural features. Previous synthetic routesto the 1,3,2-benzodiazaborole core have used organoboron dichloridesand boronic acids as the boron precursors. The transformation developedherein utilizes entirely bench stable starting materials, includingorganotrifluoroborates, enabling a wider array of substrate analoguesunder facile reaction conditions. Furthermore, physical, structural,and electronic properties of these compounds were explored computationallyto understand the influence of the B–N replacement on the structure,aromaticity, and isosteric viability of these analogues.

No MeSH data available.