Synthesis and Physicochemical Properties of 2-SF5-(Aza)Indoles, a New Family of SF5 Heterocycles

Structural diversity in heterocyclic chemistry is key to unlocking new properties and modes of action. In this regard, heterocycles embedding emerging fluorinated substituents hold great promise. Herein is described a strategy to access 2-SF5(aza)indoles for the first time. The sequence relies on the radical addition of SF5Cl to the alkynyl pi-system of 2-ethynyl anilines followed by a cyclization reaction. A telescoped sequence is proposed, making this strategy very appealing and reproducible on a gram scale. Downstream functionalizations are also demonstrated, allowing an easy diversification of N- and C3-positions. Ames test, pKa, log P, and differential scanning calorimetry measurements of several fluorinated 2-Rf-indoles are also disclosed. These studies highlight the strategic advantages that a C2-pentafluorosulfanylated motif impart to a privileged scaffold such as an indole.

Automated summary

The study presents a method for the first time access to 2-SF5(aza)indoles using radical addition of SF5Cl and cyclization reaction. A telescoped sequence is proposed for gram scale application and easy diversification of N- and C3-positions..analysis of fluorinated 2-Rf-indoles are disclosed to highlight the strategic advantages of a C2-pentafluorosulfanylated motif in indole scaffold.