Theoretical and experimental study on the in-plane S(N)2-type substitution reaction of haloalkenes with inversion of configuration at the sp(2) carbon

reaction: see text] The intramolecular in-plane S(N)2 type reaction of haloalkene E-8a was predicted to be a facile process for the first time by DFT calculations (B3LYP/6-31+G(d),SCRF(dipole, solvent = DMF)) (DeltaG = 14.4 kcal/mol). The prediction was confirmed experimentally. When E-8a was treated with NaH in DMF, benzofuran was obtained in 95% yield. On the other hand, Z-8a was recovered quantitatively even after heating at 110 degrees C.