Domino C−S/C−N Bond Formation Using Well‐Defined Copper‐Phosphine Complex Catalyst: Divergent Approach to 3‐Sulfenylated Indoles

A protocol was developed for the synthesis of 3‐thioindoles in good‐to‐excellent yields involving sulfenylation between 2‐nitrocinnamaldehydes and various thiols using a well‐defined copper(I)‐phosphine complex catalyst. This unconventional divergent approach involves in situ generation of indoles via domino C−S/C−N bond formation initiated by sulfa‐Michael addition followed by intramolecular N‐heteroannulation. This protocol shows good chemoselectivity and broad substrate scope. To briefly demonstrate the value of this approach, 2‐benzoyl‐3‐sulfenylated indoles were prepared from commercially available 2‐nitrochalcones and thiols.