Silicon-Bridged Macrocycles—Synthesis of Sila-calixarenes

摘要

Specific recognition on a molecular level requires close correspondence between the shape of the receptor and the substrate molecule, or between lock and key in the image of Emil Fischer. Macrocyclic structures can provide the necessary preor-ganization of the host for the inclusion process, and therefore most artifical receptors are cyclic molecules. Carbon is the common bridging element in natural and synthetic macrocycles, such as poiphyrins or calixarenes. However, carbon does not contribute to the binding properties of these ligands, while elements such as silicon, tin, or phosphorus can serve as additional coordination sites. We describe here the facile synthesis of silicon-bridged macrocycles, including the first silacalix[4]arene, from readily available starting materials.