1.
Org Lett
; 22(16): 6647-6652, 2020 08 21.
Article
in English
| MEDLINE
| ID: mdl-32806211
ABSTRACT
Quantification of halogen-bonding abilities is described for a series of benzimidazolium-, imidazolium- and bis(imidazolium) halogen-bond donors (XBDs) using 31P NMR spectroscopy. The measured Δδ(31P) values correlate with calculated activation free energy ΔG and catalytic activity for a Friedel-Crafts indole addition. This rapid method also serves as a sensitive indicator for Brønsted acid impurities.