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Prieschl D, Bélanger-Chabot G, Guo X, Dietz M, Müller M, Krummenacher I, Lin Z, Braunschweig H. Synthesis of Complex Boron-Nitrogen Heterocycles Comprising Borylated Triazenes and Tetrazenes Under Mild Conditions. J Am Chem Soc 2020; 142:1065-1076. [PMID: 31830413 DOI: 10.1021/jacs.9b12336] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The reactions of organic azides with diaryl(dihalo)diboranes(4) were explored, resulting in the observation of a number of surprising reactivity patterns. The reaction of phenyl azide with 1,2-diaryl-1,2-dihalodiboranes(4) resulted in the formation of five-membered rings comprising diboryl-triazenes with retention of the boron-boron bond, while the reaction of the peculiar 1,1-di(9-anthryl)-2,2-difluorodiborane(4) with phenyl azide yielded a six-membered ring bearing a diboryl-triazene, whereby the B-B bond was ruptured by the insertion of an arylnitrene-like reactive intermediate. Both types of heterocycles feature unprecedented connectivity patterns and are very rare examples of boryl triazenes beyond the more common 1,2,3-triazolatoboranes. They are also the product of a unique type of aryl migration from a boron center to the phenyl azide γ-nitrogen center. Lastly, the substitution of 1,2-diaryl-1,2-dihalodiboranes(4) with azide groups, using trimethylsilyl azide as the transfer reagent, yielded boryl-tetrazaboroles and diboryldiazadiboretidines (as side-products), invoking the intermediacy of the first N-boryl-substituted iminoboranes, which are BN isosteres of monoborylated alkynes. The synthetic results are complemented with mechanistic proposals derived from quantum-chemical calculations.
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Affiliation(s)
- Dominic Prieschl
- Institute for Inorganic Chemistry , Julius-Maximilians-Universität Würzburg , Am Hubland , 97074 Würzburg , Germany.,Institute for Sustainable Chemistry & Catalysis with Boron , Julius-Maximilians-Universität Würzburg , Am Hubland , 97074 Würzburg , Germany
| | - Guillaume Bélanger-Chabot
- Institute for Inorganic Chemistry , Julius-Maximilians-Universität Würzburg , Am Hubland , 97074 Würzburg , Germany.,Institute for Sustainable Chemistry & Catalysis with Boron , Julius-Maximilians-Universität Würzburg , Am Hubland , 97074 Würzburg , Germany
| | - Xueying Guo
- Department of Chemistry , The Hong Kong University of Science and Technology , Clear Water Bay , Kowloon , Hong Kong , China
| | - Maximilian Dietz
- Institute for Inorganic Chemistry , Julius-Maximilians-Universität Würzburg , Am Hubland , 97074 Würzburg , Germany.,Institute for Sustainable Chemistry & Catalysis with Boron , Julius-Maximilians-Universität Würzburg , Am Hubland , 97074 Würzburg , Germany
| | - Marcel Müller
- Institute for Inorganic Chemistry , Julius-Maximilians-Universität Würzburg , Am Hubland , 97074 Würzburg , Germany.,Institute for Sustainable Chemistry & Catalysis with Boron , Julius-Maximilians-Universität Würzburg , Am Hubland , 97074 Würzburg , Germany
| | - Ivo Krummenacher
- Institute for Inorganic Chemistry , Julius-Maximilians-Universität Würzburg , Am Hubland , 97074 Würzburg , Germany.,Institute for Sustainable Chemistry & Catalysis with Boron , Julius-Maximilians-Universität Würzburg , Am Hubland , 97074 Würzburg , Germany
| | - Zhenyang Lin
- Department of Chemistry , The Hong Kong University of Science and Technology , Clear Water Bay , Kowloon , Hong Kong , China
| | - Holger Braunschweig
- Institute for Inorganic Chemistry , Julius-Maximilians-Universität Würzburg , Am Hubland , 97074 Würzburg , Germany.,Institute for Sustainable Chemistry & Catalysis with Boron , Julius-Maximilians-Universität Würzburg , Am Hubland , 97074 Würzburg , Germany
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