Polycyclic Cage Compounds as Intermediates in Organic Synthesis

The utility of polycyclic "cage" molecules as intermediates in organic synthesis and as templates for constructing more complex cage and non-cage polycyclic molecules is reviewed and evaluated via examination of the following examples: (i) Cage molecules have served as starting materials for the synthesis of polyquinane natural products. (ii) In some cases, base- or acid-promoted fragmentation of readily available, appropriately substituted carbocyclic cage systems leads to the formation of unusual aromatic products. (iii) New cage systems have been accessed from simple, readily available polycyclic cage ketones and diketones by employing a variety of ring expansion processes. (iv) New crown ethers and molecular clefts have been prepared by straightforward synthetic elaboration of a number of readily available cage systems and their immediate (non-cage) precursors. l. Introduction 2. Polyquinane Synthesis 3. Aromatization Processes 4. Ring Expansion Processes 5. Synthesis of Novel Crown Ethers and Molecular Clefts 6. Concluding Remarks