Dialkylaminodifluorosulfinium Salts: XtalFluor-E and XtalFluor-M

Introduction

Fluorination is an important reaction in medicinal chemistry.[1] Fluorinated analogues of biomolecules frequently show increased biological power, lipidic permeability and metabolic stability. Diethylaminosulfur trifluoride (DAST) has been widely used for directly replacing a hydroxyl group by fluorine under very mild conditions.[2] [3] Nevertheless, the corrosive properties of DAST make it unsuitable for high-scale usage.

In this context, commercially available aminodifluorosulfinium salts,[4] such as XtalFluor-E (1) or XtalFluor-M (2), are efficient alternatives. These fluorinating agents are crystalline, more selective and significantly more stable[5] than Deoxo-Fluor or DAST and do not react violently with water.[6]

Reaction of DAST with tetrafluroboric acid provides, by elimination of HF, diethylaminodifluorosulfinium tetrafluoroborate 1 in excellent yield (Scheme [1]).[5]

Scheme 1

• References

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