Studies of the reactions of some benzenalkenyl ethers with benzenselenenyl halides

Intramolecular cyclization of some benzenalkenyl ethers with benzenselenenyl halides (PhSeX, X=Cl and Br) at different temperatures (-78 degrees C, 0 degrees C and room temperature) has been investigated. It has been found that Delta(4)-alkenyl benzyl ethers afford cyclic phenylselenoethers of the tetrahydrofuran and tetrahydropyran type, the ratio of which depends upon the number and position of alkyl substituents at the double bond and at the carbinol carbon atom. Delta(5)-Alkenyl benzyl ethers give only six-membered ether rings. The yield of cyclic phenylselenoether products decreases with an increase of the reaction temperature. PhSeCl is more efficient than PhSeBr for the cyclization reaction.