Novel solvent-free reactions with iodine:: Solid-solid and solid-vapor reactions of 1-aryl-4-(methylthio)-2-(p-tolylsulfonyl)-1,3-butadienes

Under "solvent-free" solid-solid and solid-vapor conditions, 1-aryl-4-(methylthio)-2-(p-tolylsulfonyl)-1,3-butadienes (1) react with iodine to form (p-tolylsulfonyl)naphthalene derivatives (2) in high yield. These conditions make the reaction tolerant to the kind of the aryl so that various derivatives of 2 were produced in high yield. The products (2) can be obtained in a nearly pure form by removing co-existing hydrogen iodide and dimethyl disulfide by evaporation. Thus, this process is environmentally benign, because no solvent and water need to get the pure product.