Fluorination/dearomatization of C6F5 groups: An FLP route to an electrophilic borane and non-coordinating anions

Hyehwang Kim; Dipendu Mandal; Joshua Kye Jin Ng; Zheng-Wang Qu; Stefan Grimme; Douglas Wade Stephan

doi:10.1002/chem.202401776

Fluorination/dearomatization of C6F5 groups: An FLP route to an electrophilic borane and non-coordinating anions

Chemistry. 2024 May 12:e202401776. doi: 10.1002/chem.202401776. Online ahead of print.

Authors

Hyehwang Kim¹, Dipendu Mandal¹, Joshua Kye Jin Ng¹, Zheng-Wang Qu², Stefan Grimme², Douglas Wade Stephan³

Affiliations

¹ University of Toronto, Chemistry, CANADA.
² University of Bonn, Theoretical chemistry, GERMANY.
³ University of Toronto, Chemistry, 80 St George St, M5S3H6, Toronto, CANADA.

PMID: 38735846
DOI: 10.1002/chem.202401776

Abstract

B(C6F5)3 and the corresponding anion [B(C6F5)4]- are ubiquitous in main group and transition metal chemistry. Known derivatives are generally limited to the incorporation of electron donating substituents. Herein we describe electrophilic fluorination and dearomatization of such species using XeF2 in the presence of BF3 or Lewis acidic cations. In this fashion the anions [HB(C6F5)3]-, [B(C6F5)4]- and [(C6F5)3BC≡NB(C6F5)3]-, are converted to [HB(C6F7)3]-, [B(C6F7)4]-, and [(C6F7)3BC≡NB(C6F7)3]-, respectively. Similarly, the borane adducts (L)B(C6F7)3 (L = MeCN, OPEt3) are produced. These rare examples of electrophilic attack of electron deficient rings proceed as [XeF][BF4] acts as a frustrated Lewis pair effecting fluorination and dearomatization of C6F5 rings.

Keywords: Borane adducts; Fluorination; borate salts; frustrated Lewis pairs; nonafluorohexadiene.