sixmembered

Sixmembered, often written six-membered, is a general term used in chemistry and related fields to describe structures that contain six members in a ring or ring-like framework. In organic chemistry, a six-membered ring is a cyclic arrangement of six atoms encircling a ring. Six-membered rings are among the most common and stable ring systems because they can minimize angle and torsional strain; aliphatic six-membered rings (cyclohexane) adopt conformations such as the chair to reduce strain, while aromatic six-membered rings (benzene) are planar and feature delocalized π electrons.

Common examples include cyclohexane, benzene, and heterocyclic six-membered rings such as piperidine (six-membered ring with one nitrogen) and pyran (six-membered ring with oxygen). In carbohydrate chemistry, sugars exist as six-membered pyranose rings in many forms, though five-membered furanose rings also occur.

Six-membered rings are fundamental scaffolds in pharmaceuticals and natural products, and their chemistry informs synthesis, conformational analysis, and reactivity. Nomenclature uses prefixes such as cyclo-, pyrano-, or piperido- to indicate specific six-membered ring compositions.