Alpha,beta-unsaturated ketones

Mesityl Oxide. This is an alpha-beta unsaturated ketone of high reactivity. It is used primarily as a solvent. It is also used for producing methylisobutyl ketone. 

Surh YJ, Lee SS. (1992). Enzymatic reduction of shogaol a novel biotransformation pathway for the alpha, beta-unsaturated ketone system. Biochem Int. 27(1) 179-87. 

Lauret, C. and Roberts, S. M. Asymmetric epoxidation of alpha,beta-unsaturated ketones catalyzed by poly(amino acids), Aldrichim. Acta, 2002, 35, 47-51. 

Martin NJ, List B (2006) Highly enantioselective transfer hydrogenation of alpha,beta-unsaturated ketones. J Am Chem Soc 128 13368-13369 Mayer S, List B (2006) Asymmetric counteranion-directed catalysis. Angew Chem Int Ed Engl 45 4193 1195... 

Northrup AB, MacMillan DWC (2002a) The first direct and enantioselective cross-aldol reaction of aldehydes. J Am Chem Soc 124 6798-6799 Northrup AB, MacMillan DWC (2002b) First general enantioselective catalytic Diels-Alder reaction with simple alpha,beta-unsaturated ketones. J Am Chem Soc 124 2458-2460... 

El-Suhhagh HI, Ahu-Zaid SM, Mahran MA, Badria FA, Al-Obaid AM (2000) Synthesis and biological evaluation of certain alpha, beta-unsaturated ketones and their corresponding fused pyridines as antiviral and cytotoxic agents. J Med Chem 43 2915-2921... 

Tompe, R, dementis, G., Petnehazy, I., Jaszay, Z.M. and Toke, L. (1995). Quantitative Structure Electrochemistry Relationships of Alpha,Beta Unsaturated Ketones. Anal. Chim.Acta, 305, 295-303. 

Di Cosimo. Jl Die/, VK Apesteguia. CR. Base catalysis for the synthesis of alpha, beta-unsaturated ketones from the vapor-phase aldol condensation of acetone. Applied Catalysis A GeneraL 1996 137. 149-166,... 

Torey, C., Henin, F., Muzart, J. (1996) Enantioselective hydrogenation of alpha,beta-unsaturated ketones over Pd on charcoal in the presence of (-)-ephedrine, Tetrahedron Asymm. 7, 975-976. 

Fogassy, G., Tangier, A., Levai, A., Toth, G. (2002) Enantioselective hydrogenation of exocyclic alpha,beta-unsaturated ketones. Part II. Hydrogenation in the presence of (S)-proline, J. Mol. Catal. A. Chem. 179, 101-106. 

Cho, C. S. Motofusa, S.-i. Ohe, K. Uemura, S. Shim, S. C. A New Catalytic Activity of Antunony(III) Chloride in PaUadium(0)-Catalyzed Conjugate Addition of Aromatics to alpha, beta-Unsaturated Ketones and Aldehydes with Sodium Tetraphenylborate and Arylboronic Acids. /. Org. Chem. 1995, 60,883-888. 

Citing Pape r the tin(ii) enolate addition-reactions to alpha.beta-unsaturated ketones and quinones. 

Xu, W., Jeon, Y.T., Hasegawa, E., Yoon, U.C., and Mariano, P.S., Novel electron transfer photocy-clization reactions of alpha-silylamine alpha,beta-unsaturated ketone and ester systems, /. Am. 

Group-transfer polymerizations make use of a silicon-mediated Michael addition reaction. They allow the synthesis of isolatable, well-characterized living polymers whose reactive end groups can be converted into other functional groups. It allows the polymerization of alpha, beta-unsaturated esters, ketones, amides, or nitriles through the use of silyl ketenes in the presence of suitable nucleophilic catalysts such as soluble Lewis acids, fluorides, cyanides, azides, and bifluorides, HF. ... 

Based on the above discussion it was thought that the trifluoro-methyl ketones would be more polarized and thus create a great electrophilicity on the carbonyl carbon which facilitates -OH attack by the serine residue. Yet there is no carbon-oxygen bond to be cleaved In the ketone moiety, and therefore the enzyme-trifluoromethyl ketone transition state complex does not undergo catalytic conversion. The above rationale seems reasonable as trifluoromethyl ketones were found to be extraordinary selective and potent inhibitors of cholinesterases (56) of JHE from T. ni (57) and of meperidine carboxylesterases from mouse and human livers (58). Since JH homologs are alpha-beta unsaturated esters, a sulfide bond was placed beta to the carbonyl in hopes that it would mimic the 2,3-olefln of JHs and yield more powerful inhibitors (54). This empirical approach was extremely successful since it resulted in compounds that were extremely potent inhibitors of JHEs from different species (51,54,59). 

Ponec V (1997) On the role of promoters in hydrogenation on metals alpha, beta-unsaturated aldehydes and ketones. Appl Catal 149 27... 

Figure 5. Some branched cycloses, cyclitols and alpha, beta-unsaturated cyclic ketones derived from xylaric acid some acyclic c> /o (8 - 9) and ribo (10) ring precurors.

Dehydration of an aldol product is no more than a functional group interconversion, so the retrosynthesis of a a,P-unsaturated ketone or aldehyde involves making the same disconnection as used for a P-hydroxy ketone or aldehyde between the alpha and beta carbons. It may help to start the retrosynthesis by adding water back in (undoing the dehydration step) to give the more recognizable P-hydroxy carbonyl compound before making the disconnection. 

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