Cyclohexenones decarboxylation

The third and fourth steps in the synthesis of Hagemann s ester from ethyl acetoacetate and formaldehyde (Problem 23.50) are an intramolecular aklol cyclization to yield a substituted cyclohexenone, and a decarboxylation reaction. Write both reactions, and show the products of each step. 

Certain substituted cyclohexenones are made by an analogous internal aldol condensation and decarboxylation of his-estets resulting from condensation of aldehydes with acetoacetic ester. 

Decarboxylation of amino acids. Amines are obtained on heating a-amino acids with 2-cyclohexenone (3 examples, 72-82% yield). 

Scheme 7.17 One-pot procedure for the synthesis of cyclohexenones by Michael/ aldol/dehydration/decarboxylation sequence.

Draw the product of the Michael addition of methyl acetoacetate to 2-cyclohexenone. Draw the product obtained by hydrolyzing the adduct followed by heating to decarboxylate the intermediate acid. 

Su, Z., Mariano, P.S., Falvey, D.E., Yoon, U.C,. and Oh, S.W, Dynamics of anihnium radical a-heterolytic fragmentation processes. Electrofugal group, substituent and medium effects on desi-lylation, decarboxylation and retro-Aldol cleavage pathways, /. Am. Chem. Soc., 120, 10676,1998. Hasegawa, E., Xu, W, Mariano, P.S., Yoon, U.C., and Kim, J.U., Electron transfer induced photoadditions of the silylamine EtjNCHjTMS to a,P-unsaturated cyclohexenones. Dual reaction pathways based on ion pair selective cation radical chemistry, /. Am. Chem. Soc., 110, 8099, 1988. Yoon, U.C., Kim, J.U., Hasegawa, E., and Mariano, P.S., Electron transfer photochemistry of a-silylamine cyclohexenone systems. Medium effects on reaction pathways followed, /. Am. Chem. Soc., 109, 4421,1987. 

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