Facile ring-closure cyclization of arenes by nucleophilic C-allylation reaction in ionic liquid (original) (raw)

A novel synthetic method using an ionic liquid (IL) for a six-membered ring-closure cyclization is described. The ring-closure cyclization by nucleophilic C-alkylation was achieved with various haloand alkanesulfonyloxyalkyl aromatic compounds in high yields with minimal byproducts using ILs as the reaction media in the absence of any catalyst. For example, the cyclization of 2-(3-methanesulfonyloxy-propoxy)naphthalene (1a) to 2,3-dihydro-1H-naphtho[2,1-b]pyran (2) in IL [bmim] [PF 6 ] proceeded selectively at 150°C for 24 h in 85% yield.