An environmentally benign and high-rate Appel type reaction†
A high rate, selective, and productive Appel type reaction was developed. The method allows for ipso-substitution of the alcoholic hydroxy group with halogens ∈ [Cl, Br, I]. The method demands mild reaction conditions that include a very short reaction time, <15 min only, versus reaction times of several hours or days using the classical Appel reaction conditions (PPh3 + CCl4 + R–OH). The method was demonstrated to operate with the cheap and easily available 1,3-dihalo-5,5-dimethylhydantoins and N-halo succinimides (halo ∈ [Cl, Br, I]) as the reagent that performs the halogenation of PPh3. The reaction protocol operated with several acceptable solvents rather than DCM that was used in the classical Appel reaction. Furthermore, the batch protocol was also translated and successfully implemented on a flow reactor platform (t < 5 min, y = 95%).