Robinson Annulation Mechanismbetween 2 Methylcyclohexene And Methyl Vinyl Ketone

These are organic compounds containing a ketone that is conjugated to a cyclic moiety.

Robinson annulation mechanismbetween 2 methylcyclohexene and methyl vinyl ketone.

As illustrated in the following figure the robinson annulation reaction involves two steps the first step involves the michael addition of a ketone enolate the enolate derived from cyclohexanone in the example pictured below to an alpha beta unsaturated ketone methyl vinyl ketone below. 1 michael addition 2 intramolecular aldol condensation. Robinson annulation is a fundamental organic reaction in particular because it is at the base of the synthesis of steroids and other important molecules even of pharmaceutical interest. The cyclodehydration of 3 catalyzed by l proline is then performed at 25 c by simple stirring under argon for 120 h.

The first step in the process is the michael addition to an α β unsaturated ketone such as methyl vinyl ketone ethyl vinyl ketone is shown above. The annulation reaction has as its most common substrates generally cycle hexanone and methyl vinyl ketone. The reaction involves two important steps. The optimized procedure 6 2 methyl 2 3 oxobutyl 1 3 cyclohexanedione 3 is prepared by heating 2 methylcyclohexane 1 3 dione 2 with methyl vinyl ketone 1 in aqueous acetic acid at 75 c for 1 h after which 3 is purified.

The newly formed enolate intermediate must first tautomerize for the conversion to continue. The journal of organic chemistry 45 p. Investigation in the field of stereochemistry of polycyclic compounds monoesters of cis and trans 1 methyl 1 2 cyclohexanedicarboxylic acids or 1 methyl 4 cyclohexene 1 2 dicarboxylic acids and their conversion. 2 methylcyclohexanone exists as a liquid slightly soluble in water and an extremely weak basic essentially neutral compound based on its pka.

2 methylcyclohexanone also known as fema 3946 or tetrahydro o cresol belongs to the class of organic compounds known as cyclic ketones. Cyclohexenones are compounds containing a cylohexenone moiety which is a six membered aliphatic ring that carries a ketone and has one endocyclic double bond. In a second step the methyl group adjacent to the carbonyl is deprotonated and undergoes an. 3 methyl 2 cyclohexen 1 one exists as a solid slightly soluble in water and an extremely weak acidic.

Michael addition of cyclohexanones to methyl vinyl ketone followed by intramolecular aldol condensation to afford six membered α β unsaturated ketones. Mechanism of the robinson annulation. 2 methylcyclohexanone is a cyclic ketone that is reported to occur in mint and horse chestnut.