11membered

11membered refers to a ring structure containing eleven atoms. In chemistry, such ring sizes are considered medium-sized rings, a category often associated with increased conformational complexity and a higher propensity for certain types of reactions compared to smaller or larger rings. The strain in an 11-membered ring is generally less than in very small rings like cyclopropane or cyclobutane, but it is still significant enough to influence its properties.

These rings can be composed of various atoms, most commonly carbon atoms, forming cycloalkanes such as cycloundecane. However, 11-membered rings can also incorporate heteroatoms like nitrogen, oxygen, or sulfur, leading to heterocycles with diverse chemical behaviors and applications. Examples include macrocyclic compounds which are often used in medicinal chemistry, materials science, and as ligands in coordination chemistry.

The synthesis of 11-membered rings can be challenging due to entropic factors and potential side reactions that favor smaller or larger ring formation. Specialized cyclization reactions, often employing high dilution techniques, are typically required to achieve good yields. The study of 11-membered rings contributes to the broader understanding of ring strain, conformational preferences, and the synthesis of complex molecular architectures.