@M04021@ which contain both an aldehydic and a ketonic carbonyl group in equilibrium with @I03130@ hemiacetal forms.
See also:
oxo compounds
Source: PAC, 1995, 67, 1307. (Glossary of class names of organic compounds and reactivity intermediates based on structure (IUPAC Recommendations 1995)) on page 1346 [Terms] [Paper]