Loading VerChem
Preparing your chemistry tools...
Preparing your chemistry tools...
Also known as: Robinson Ring Formation
Discovered by Robert Robinson (1935)
A tandem Michael addition followed by intramolecular aldol condensation that constructs a new 6-membered ring fused to the existing ketone. This one-pot reaction creates one ring, two C-C bonds, and three stereocenters.
Michael addition: The enolate of the ketone adds in a 1,4-fashion to the methyl vinyl ketone (Michael acceptor), giving a 1,5-diketone.
Michael addition (see Michael reaction)
Intramolecular aldol: One of the ketone enolates attacks the other ketone carbonyl within the same molecule, forming a 6-membered ring with a β-hydroxy ketone.
Intramolecular aldol cyclization
Dehydration: The β-hydroxy ketone loses water to form the conjugated cyclohexenone product.
Aldol condensation — forms the enone
2-Methylcyclohexanone + MVK
NaOH, EtOH, heat
Bicyclic enone (Hajos-Parrish ketone precursor)
The classic method for building 6-membered rings onto existing ketones. Critical in steroid and terpene synthesis.