Radical Cyclizations of N‐Methylallyl‐2‐arylindoles with Polychloromethanes to Assemble Polychloroalkylated Indolo[2,1‐a]isoquinolines

An efficient synthesis of polychloroalkylated indolo[2,1‐a]isoquinolines has been achieved via aryldiazonium salt induced radical cyclization reaction of N‐methylallyl‐2‐arylindoles with polychloromethanes. In this reaction, neither metal catalyst nor additional oxidant was required, and an isoquinoline ring was constructed by tandem radical additions on the nonactivated carbon−carbon double bond of allyl group in 2‐arylindoles. This protocol features advantages of wide substituent scope, environmentally friendly conditions and good yields.