New synthetic approach to cyclopenta-fused heterocycles based upon a mild nazarov reaction. 2. Further studies on the torquoselectivity

Reporting on the torquoselectivity in the cyclization of 2-substituted five-membered azacycle and 2- and 4-substituted six-membered oxacycle derivatives. The reaction is highly diastereoselective with 2-substituted five-membered lactam derivatives 11a and 11b and leads to cis disubstituted cyclopenta-fused pyrrolines 13a and 13b, respectively.