formylate

Formylate is a chemical term used to describe the introduction of a formyl group (-CHO) into a molecule, or the conversion of a substrate into a formyl derivative. The result is a formylated compound such as a formamide, a formyl ester, or an N-formyl or O-formyl derivative, depending on the reactive site and reagents used.

In organic synthesis, formylation is achieved with a range of reagents. Electrophilic formylation of activated substrates can employ Vilsmeier–Haack reagents, typically a combination of dimethylformamide and phosphoryl chloride, to formylate aromatic rings. Other reagents include formyl chloride, formic anhydride, or formic acid in various catalytic contexts, which can formylate amines to give formamides or alcohols to give formyl esters. The formyl group can also serve as a temporary protecting group or as a handle for further transformations.

In biological systems, formylation occurs in specific contexts. In many bacteria, the initiating amino acid is N-formylmethionine, produced by transfer of a formyl group from N10-formyltetrahydrofolate to methionine, enabling the start of protein synthesis. Formylglycine generation is a post-translational modification in certain enzymes, produced by formylglycine-generating enzymes that convert cysteine to formylglycine, a key cofactor in sulfatases.

Formylation also appears in synthetic chemistry to prepare protecting groups or to enable subsequent reactions. The term formylate is sometimes used as a synonym for formylating or formylation, though formylation is the more common term in academic writing.

Formylate reagents are generally handled with care due to the toxicity and reactivity of formylating agents.