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p-(Difluoroiodo)toluene (p-TolIF2) is a versatile fluorinating agent that acts as both a surrogate for elemental fluorine, and as a source of ‘electrophilic’ fluorine. Described here is a detailed three-step synthesis of p-TolIF2, carried out on a 50 mmol scale, that consistently provides high-quality product that is suitable for long-term storage. The reactions employ inexpensive, readily available starting materials and reagents, and uses the commodity chemical 48% aqueous HF as the source of fluorine atoms.

A rapid, mild and metal-free intermolecular cyclopropanation between iodonium ylides and alkene-containing substrates mediated by PhI(OAc)2·Bu4NI is reported. Iodonium ylides of cyclic and acyclic 1,3-dicarbonyls were reacted with a variety of mono-, di-, tri- and tetra-substituted alkenes of various structural types to give 29 cyclopropanes in up to 97% yield.

A combined experimental and computational investigation was conducted to identify a mild and effective Lewis-acidic activator for TolIF2 in the gem-difluorination of diazo compounds. Computationally, borosilicate, a common constituent of laboratory glassware, was found to spontaneously activate TolIF2, and an extensive experimental survey confirmed borosilicate as the most effective activator to date. The key to realizing this borosilicate-activated reaction was the use of high purity TolIF2, which is prepared by a reproducible, multigram-scale synthesis.

An iodide-mediated reaction between cyclic iodonium ylides of 1,3-dicarbonyls and 3-alkylidene-2-oxindoles results in 3H-spiro[furan-2,3′-indolin]-2′-ones. The reaction was tolerant to substitutions on both the alkylidene and ylide substrates and provided access to 19 new, densely functionalized polycyclic spirocycles in typically high yield.