oformyl

Oformyl, or O-formyl, is a chemical term used to describe a formyl group that is attached to a molecule via an oxygen atom. In this usage, the formyl moiety is the aldehyde fragment -CHO, linked through the oxygen to the rest of the molecule, forming formate esters. The best-known examples are formate esters such as methyl formate (HCOOCH3) and ethyl formate (HCOOEt), in which the formyl group is connected to an alkoxy group through an O–C(=O) linkage.

O-formylation is a common transformation in organic synthesis used to introduce a formyl group onto substrates bearing oxygen-containing functions, typically alcohols or phenols, to yield formate esters. This approach can serve as a protecting strategy or as an intermediate step in further transformations. Reagents used for O-formylation include formylating agents such as formic acid derivatives or formyl chlorides, often under dehydrating conditions or with suitable catalysts. Hydrolysis or transesterification of O-formyl esters regenerates the original alcohol or phenol and forms formic acid.

Terminology-wise, the descriptor “O-formyl” helps distinguish this linkage from other possible attachments of a formyl group, such as N-formyl or C-formyl. In structural notation, O-formyl derivatives are exemplified by formate esters where the formyl group is bonded through oxygen to another substituent.

Applications of O-formyl derivatives appear in organic synthesis, flavor and fragrance chemistry (where esters contribute characteristic scents), and various protecting-group strategies in carbohydrate and peptide chemistry. See also: Formate, Formyl group, Ester, Formic acid, Formylation.