Synthesis of Selenocyanated Indoles via PhICl₂‐Induced Electrophilic Intramolecular Cyclization of 2‐Alkynylanilines or 2‐Alkenylanilines

Abstract

The 3‐selenocyanato‐substituted indoles were readily synthesized via PhICl2‐induced reaction of 2‐alkynylanilines or 2‐alkenylanilines with KSeCN in MeCN under metal‐free conditions. The reaction sequence was postulated to encompass the formation of a reactive selenocyanogen chloride species, generated in situ from the reaction of PhICl2 and KseCN, followed by electrophilic addition and intramolecular cyclization steps.

Visible-light induced selenocyclization of 2-ethynylanilines under ambient conditions: simple FeBr3 as a dual-functional catalyst

“…Compared with direct selenylation of pre-constructed indoles at the C3-position, 5 selenocyclization of 2-ethynylanilines is a more step-economical strategy which simultaneously forms the indole skeleton in a single step (Scheme 1a). 6–11 Accordingly, oxidative selenocyclization methods have been developed using stable diselenides as selenylating reagents, along with chemical oxidants such as CuBr 2 or K 2 S 2 O 8 , 6 a PhICl 2 6 b and Selectfluor® 6 c under mild conditions, or in air in the presence of CuI/Cs 2 CO 3 at elevated temperature. 6 d , e Base-promoted selenocyclization has also been reported, although suffering from harsh conditions and low atom-utilization of diselenides.…”