Visible-Light-Driven C-3 Selenocyanation of Indoles with Elemental Selenium and TMSCN

We develop a photocatalyst-free, visible-light-driven three-component reaction of indole, elemental selenium, and TMSCN in air at room temperature to synthesize indole 3-selenocyanoates. This protocol features eco-friendly, photocatalyst-free, elemental selenium, and TMSCN serves as the source of "SeCN". Notably, the gram-scale reaction and product derivatizations demonstrated the practicality and effectiveness of this synergistic protocol. Preliminary mechanistic investigations indicate that light-absorbing species 2,3,4,6,7,8,9,10-octahydro-1H-pyrimido[1,2-a]azepin-5-ium selenocyanate is generated in situ from DBU, elemental selenium, and TMSCN.