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Media type:
E-Article
Title:
Benzyl Borane NHC Adducts: Beyond B−C Bond Scission
Contributor:
Böser, Richard;
Denker, Lars;
Frank, René
Published:
Wiley, 2019
Published in:
Chemistry – A European Journal, 25 (2019) 45, Seite 10575-10579
Language:
English
DOI:
10.1002/chem.201902698
ISSN:
0947-6539;
1521-3765
Origination:
Footnote:
Description:
AbstractBenzyl‐substituted boronates and borates are widely employed as mild sources in radical or anionic transfer reactions of benzyl entities. In this process the B−C bond to the benzyl moiety is essentially ruptured. In contrast, reactions with retention of the B−C bond are poorly investigated although several other reactive sites in benzyl–boron systems are clearly inherent. In this respect, the novel reactivity of the representative borane adduct IiPr−BH2Bn [IiPr=:C{N(iPr)CH}2, Bn=CH2C6H5] is demonstrated. Dihalogenation of the BH2 entity is observed with BCl3 and BBr3, whereas BI3 either affords IiPr−BHI2 or proceeds with borylation of the aromatic phenyl ring to give a hydride‐bridged bisborylated species. The photochemical mono‐ and dihalogenation of the benzylic CH2 group was demonstrated with elemental bromine Br2. The brominated product IiPr−BBr2−CHBr−C6H5 was borylated at the benzylic carbon atom in an umpolung event with BI3 to afford the zwitterion IiPr−BI−CH(BI3)−C6H5.