Fluorocyclisation via I(I)/I(III) catalysis: a concise route to fluorinated oxazolines.

Herein, we describe a catalytic fluorooxygenation of readily accessible -allylcarboxamides via an I(I)/I(III) manifold to generate 2-oxazolines containing a fluoromethyl group. Catalysis is conditional on the oxidation competence of Selectfluor, whilst HF serves as both a fluoride source and Brønsted acid activator. The C(sp)-F bond of the mono-fluoromethyl unit and the C(sp)-O bond of the ring are aligned in a relationship thereby engaging in stabilising hyperconjugative interactions with , electron-rich σ-bonds (σ→σ* and σ→σ*). This manifestation of the stereoelectronic effect was established by X-ray crystallographic analysis of a representative example. Given the importance of fluorine in drug discovery, its ability to modulate conformation, and the prevalence of the 2-oxazoline scaffold in Nature, this strategy provides a rapid entry into an important bioisostere class.