Chirality Relay in 2,2′-Substituted 1,1′-Binaphthyl: Access to Propeller Chirality of the Tricoordinate Boron Center
| Autor: | Zuo-Bang Sun, Chen Wang, Cui-Hua Zhao, Qing-Wen Xu |
|---|---|
| Rok vydání: | 2016 |
| Předmět: |
Steric effects
010405 organic chemistry Stereochemistry Organic Chemistry Propeller chemistry.chemical_element General Chemistry Borane 010402 general chemistry Ring (chemistry) 01 natural sciences Catalysis 0104 chemical sciences chemistry.chemical_compound chemistry Axial chirality Moiety Chirality (chemistry) Boron |
| Zdroj: | Chemistry - A European Journal. 22:16750-16754 |
| ISSN: | 0947-6539 |
| Popis: | It is a challenging issue to achieve propeller chirality for triarylboranes owing to the low transition barrier between the P and M forms of the boron center. Herein, we report a new strategy to achieve propeller chirality of triarylboranes. It was found that the chirality relay from axially chiral 1,1'-binaphthyl to propeller chirality of the trivalent boron center can be realized when a Me2 N and a Mes2 B group (Mes=mesityl) are introduced at the 2,2'-positions of the 1,1'-binaphthyl skeleton (BN-BNaph) owing to the strong π-π interaction between the Me2 N-bonded naphthyl ring and the phenyl ring of one adjacent Mes group, which not only exerts great steric hindrance on the rotation of the two Mes groups but also gives unequal stability to the two configurations of the boron center for a given configuration of the binaphthyl moiety. The stereostructures of the boron center were fully characterized through 1 H NMR spectroscopy, X-ray crystal analyses, and theoretical calculations. Detailed comparisons with the analog BN-Ph-BNaph, in which the Mes2 B group is separated from 1,1'-binaphthyl by a para-phenylene spacer, confirmed the essential role of π-π interaction for the successful chirality relay in BN-BNaph. |
| Databáze: | OpenAIRE |
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