A chemical shift additivity method for the prediction of fluorine-19 chemical shifts in fluoroaromatic compounds

Reactions of HMPA with hexafluorobenzene, pentafluorochlorobenzene and pentafluorophenol

“…The product 4b and 4c were fully characterized by 1 H NMR, 19 F NMR, elementary analysis and MS. The substitution position of the second and the third dimethylamino group was confirmed by the 19 F NMR and 1 H NMR, as mentioned in the literatures [24,25]. A doublet with 5 J (F-H) 2.1 Hz and a triplet with 5 J (F-H) 1.8 Hz in the 1 H NMR of 4b indicated that there exist two kinds of proton, in which one was coupled with one fluorine and the other with two [25].…”

“…Thus the third dimethylamino group should be bonded to C6 (4c) (Scheme 1). Besides, the 19 F chemical shifts confirmed further the substitution position of the dimethylamino groups [24]. In order to gain deep insight into these reactions, we extended our investigation to pentafluorophenol, as shown in Scheme 2.…”

19F NMR chemical shift prediction with fluorine fingerprint descriptor

“…An updated in-depth book on this subject was recently published [17]. Several approaches have been proposed in the literature for predicting the isotropic fluorine chemical shift ranging from ab initio calculations based on Hartree-Fock GIAO methods ( [18][19][20][21][22] and references cited therein) to empirical-rules based on experimentally measured substituent effects (see for example [23][24][25] and references cited therein). Here we present a novel method for predicting the fluorine chemical shift that is based on the recently introduced fluorine fingerprint descriptor [11].…”

New insight on the cycloaddition of aryl and heteroaryl azides with (trimethylsilyl)acetylene. Spectroscopic and x-ray crystallographic data of silylated 1,2,3-triazoles

“…12 (Trimethylsilyl)acetylene was purchased from Aldrich Chimica Italiana and degassed with nitrogen before the use. Caution -Hydrazoic acid and organic azides are potentially explosive!…”