Cyclooligomerization with Transition Metal Catalysts

This report is concerned not only with the syntheses of new ring systems and the preparation of derivatives of known rings but also with new types of catalysts based upon, e. g., nickel, iron, molybdenum, manganese, and palladium. The broad applicability of the methylene insertion reaction as a method for identifying mono‐ and di‐methyl‐substituted eight‐, ten‐, and twelve‐membered rings is also demonstrated. A further section is concerned with the possible mechanism of CC bond formation in transition metal complexes; several earlier suggestions have been revised in the light of new experimental data. In addition, experimental results are discussed which indicate that the reactivity and selectivity of the complexes formed by the nickel‐ligand catalyst and olefins or alkynes depend upon the structure of the ligands.