Efficient and general synthesis of oxazino[4,3-a]indoles by cascade addition-cyclization reactions of (1H-indol-2-yl)methanols and vinyl sulfonium salts.

An efficient and general approach to oxazino[4,3-a]indole architectures is described. The addition-cyclization cascade of (1H-indol-2-yl)methanols with vinyl sulfonium salts affords oxazino[4,3-a]indole derivatives in high yields.