5deoxy

5-deoxy is a chemical descriptor used in organic chemistry and biochemistry to indicate that a molecule lacks an oxygen-containing substituent at the fifth position relative to a standard parent framework. The term is most often encountered in the naming of sugars, nucleosides, nucleotides, and related natural products where carbon numbering is explicit and the presence or absence of oxygen at specific positions matters for structure and function.

In practice, 5-deoxy denotes a structural variant in which the typical oxygen substituent at the fifth carbon is missing or substituted by hydrogen or another non-oxygen group. It is one of several deoxy prefixes used in systematic nomenclature, alongside 2-deoxy, 3-deoxy, and others, to convey precise modifications of a parent molecule. Because it is a descriptor rather than a standalone compound, a full chemical name must specify the exact skeleton and substituents to identify the molecule uniquely.

The use of 5-deoxy appears across contexts including carbohydrate chemistry, where sugar derivatives are modified at various positions, and in studies of nucleoside analogs and natural products. Researchers employ such terminology to distinguish regioselectively deoxygenated variants that may exhibit different biochemical properties or activities compared with their oxygen-containing counterparts.

Overall, 5-deoxy serves as a systematic shorthand within the broader framework of IUPAC-style naming, signaling a specific deoxygenation at the fifth position without prescribing a single structural formula.