Ethyl 2-oxocyclohexanecarboxylate

Synthesis

Diethyl carbonate (146 mL, 1.2 mol) and 150 mL of dry tetrahydrofuran were added to a 1000 mL three-necked flask. NaH (60%, 63 g, 1.6 mol) was added with stirring. After reflux for 1 h, a THF solution of cyclohexanone (50 mL, 0.48 mol) was added dropwise over approximately 0.5 h. After the addition was complete, reflux was continued for another 1.5 h. After cooling, the solution was adjusted to neutral with 3N hydrochloric acid, then poured into brine and extracted with dichloromethane (75 mL × 3). After drying the organic layer, vacuum distillation yielded a brown oily liquid (66 g, 80% yield), which was crude Ethyl 2-oxocyclohexanecarboxylate, and could be used directly in the next reaction.

Chemical Properties

Clear colorless to pale yellow liquid

Uses

Ethyl 2-Oxocyclohexanecarboxylate is used in biocatalysis.

Uses

Ethyl 2-oxocyclohexanecarboxylate is used to produce other chemicals. For example, it can react with 4-methyl-aniline to get 2-oxo-cyclohexanecarboxylic acid p-toluidide. The reaction occurs with reagent DMAP

Reactions

The reaction of ethyl 2-oxo cyclohexane carboxylate (I) with phenyl vinyl sulphoxide (II) and sodium hydride followed by pyrolysis of the resulting phenyl sulphonyl ethyl compound (III) gives the 1-vinyl compound (IV).
Baeyer-Villiger oxidation of methyl 3- and 4-oxocyclohexanecarboxylates gave the expected hexanolides, whereas ethyl 2-oxocyclohexanecarboxylate(I) gave 5-ethoxyoxalylpentanoic acid by way of ethyl 1-hydroxy-2-oxocyclohexanecarboxylate, formed by epoxidation of the enol form of (I)[1-2].

Synthesis Reference(s)

Canadian Journal of Chemistry, 42, p. 1333, 1964 DOI: 10.1139/v64-205
The Journal of Organic Chemistry, 53, p. 878, 1988 DOI: 10.1021/jo00239a038
Tetrahedron Letters, 7, p. 2201, 1966

References

[1] A. Hubert, P. S. Starcher. “The Baeyer-Villiger oxidation of alkyl oxocyclohexanecarboxylates.” Journal of The Chemical Society C: Organic 377 1 (1968): 2500–2502.
[2] G. Koppel, M. D. Kinnick. “Phenyl vinyl sulphoxide, a vinyl carbonium ion synthetic equivalent.” Journal of The Chemical Society, Chemical Communications 27 1 (1975): 473–473.