81791-31-3

Upstream product

• 81791-30-2 (E)-4-hydroxy-1-(4-methoxyphenyl)-4-methylpent-1-en-3-one 
• 98017-82-4 C₁₃H₁₆O₃ 
• 123-11-5 4-methoxy-benzaldehyde 
• 115-22-0 3-Hydroxy-3-methyl-2-butanone 

Downstream Products

• 327982-94-5 5-(4-methoxyphenyl)-2,2-dimethyltetrahydrofuran-3-one oxime 
• 81791-30-2 (E)-4-hydroxy-1-(4-methoxyphenyl)-4-methylpent-1-en-3-one 

Relevant academic research and scientific papers

Reversal of Electronic Effects between Inter- and Intra-molecular Michael Addition Reactions

Measurement of the rates of cyclisation of (E)-2-methyl-3-oxo-5-phenylpent-4-en-2-ol and its p-methoxy-derivative in trifluoroacetic acid, together with the rates of the reverse reaction, indicates an influence of stereoelectronic origin which is not present in intermolecular Michael additions.

On the reaction of sterically hindered α,β-unsaturated ketones with hydroxylamine: Preparation of 5-hydroxy derivatives of isoxazolidine and 4,5-dihydroisoxazole

A reaction of hydroxylamine with α,β-unsaturated ketones containing a tertiary carbon atom α to the keto group leads to 5-hydroxyisoxazolidine and 5-hydroxy-Δ2-isoxazoline derivatives.

Stereoelectronic effects in ring closure reactions: the 2'-hydroxychalcone-flavanone equilibrium, and related systems

The 2'-hydroxychalcone (2-HOC6H4COCH=CHC6H4X)-flavanone equilibrium in trifluoroacetic acid (TFA) has been examined.The influence of substituents X on the rate of attainment of equilibrium shows that the 6-endo-trig mode of ring closure by Michael addition is disallowed, by demonstrating a negative ρ value for the reaction rate when X is varied.Reaction therefore proceeds either on the carbonyl-protonated form, which allows twisting about the 2,3 double bond, its double bond character being reduced by resonance, or through direct rate-limiting protonation on the 2,3-double bond.Either pathway permits the allowed 6-exo-trig mode of ring closure to be followed.Alternative mechanism involving intermolecular Michael addition of trifluoroacetate, followed by intramolecular 6-exo-tet displacement are considered.Such Michael adducts can be detected in the ring closures of 2-crotonyl-4-methylphenol and 4,4-dimethyl-1-(2-hydroxyphenyl)-2-penten-1-one in TFA, but they do not appear to lie on the main pathway, because the reaction proceed with equal facility in methanesulphonic acid/chloroform medium, which does not contain a suitable nucleophile for such a mechanism.Further important mechanistic information is given by studying the reactions in TFA-d, together with measurements on the (E)-2-methyl-3-oxo-5-arylpent-4-en-2-ol and flight during the rate-limiting step, and provide evidence against the mechanism involving a preequilibrium carbonyl protonation, such as in the Nazarov rearrangement of 3'-methoxychalcones, where KH/kD is ca. 0.7.Some results are also reported for ring closure of the 2-aminochalcones in TFA.

Stereoelectronic Control of Intramolecular Michael Addition Reactions

Concepts of stereoelectronic control lead to the conclusion that the 5-endo-trig ring closure of (E)-2-methyl-3-oxo-5-phenylpent-4-en-2-ol should be disfavored.However, the acid-catalyzed ring closure in trifluoroacetic acid occurs readily, suggesting an