Transition metal-free direct trifluoromethylthiolation of indoles using trifluoromethanesulfonyl chloride in the presence of triphenylphosphine.

A novel triphenylphosphine-mediated direct trifluoromethylthiolation of indole derivatives using trifluoromethanesulfonyl chloride as the SCF3 source was developed. Sodium iodide facilitated this transformation by generating iodine in situ which was found to accelerate this transformation. The use of a transition metal-free protocol, readily available reagents, and mild reaction conditions allowed this protocol to be easily scaled up.