Mn(OAc)3-promoted sulfur-directed addition of an active methylene compound to alkenes

Various alkenes substituted at the 1,2-positions by phenyl, thiophene and furan rings were reacted with 3-(4-methoxyphenyl)-3-oxopropanenitrile in the presence of Mn(OAc)3·2H2O. The exact structure and configuration of the dihydrofuran derivatives formed were determined. In all cases only one regioisomer was formed. The observed regioselectivity was explained on the basis of the formation of a complex between Mn(OAc)3, alkene, and 3-(4-methoxyphenyl)-3-oxopropanenitrile, which directs the mode of the addition to the double bond.