The apparent electrophilic fluorination of 1,3‐dicarbonyl compounds using Et3N·3HF as a nucleophilic fluoride source is reported. This reaction requires PhI(OAc)2 as oxidant and can be conducted safely in standard laboratory glassware. Alternative selectivity compared to Selectfluor was observed in some cases. This approach may reduce our reliance on difficult‐to‐handle fluorine gas and expensive electrophilic fluorinating agents derived from elemental fluorine. Mechanistic analysis related to the active fluorinating species and fluoride/acetate exchange is presented.
Optimized procedures are developed for the fluorination of 2-substituted ring systems and for di-or monofluorination of unsubstituted chains. In all cases, the NEt 3·3HF/Ph-I(O-Ac)2 combination works with optimal results and the protocol is compatible with a gram-scale access. Product (Xb) is isolated as the hydrate. The usefulness of (XIIb) as precursor of fluorinated heterocycles is demonstrated with the synthesis of pyridone (XIV). The mechanism of the halogenation including all complex side reactions is investigated and discussed in detail. -(NASH, T. J.; PATTISON*, G.; Eur.
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