13945-24-9Relevant academic research and scientific papers
Cation-Anion Combination Reactions. 20. Reactions of Nucleophiles with trans-3-Methoxy- and trans-3-(Methylthio)acrylophenones
Ritchie, Calvin D.,Kawasaki, Atsushi
, p. 4704 - 4708 (1981)
The reactions of a number of nucleophiles with trans-3-methoxyacrylophenone (MeOAcr) and with trans-3-(methylthio)acrylophenone (MeSAcr) in water and methanol have been studied.The reactions of amines produce enamines as the first observable products, and primary amines show simple kinetics: first-order with respect to amine and first-order with respect to the acrylophenone.Piperidine reactions show kinetics which are consistent with a change in the rate-determining step with a change in amine concentration.Methoxylamine reactions produce the monooximes, and semicarbazide reactions produce the monosemicarbazone with MeOAcr but the disemicarbazone with MeSAcr.The reactions of hydroxide ion produced the enolate of benzoylacetaldehyde, which, at the high base concentration used in the MeSAcr reaction, was further converted to acetophenone and formate ion.Methoxide and cyanide ion reactions given addition across the double bond.Rate constants for the reactions of MeOAcr are 20-1000 times greater than those for corresponding reactions of MeSAcr.There is a very good correlation of the rate constants for reactions of nucleophiles with MeOAcr and those with 2,4-dinitrophenyl acetate in both water and methanol solution.
The α-effect in reactions of sp-hybridized carbon atom: Michael-type reactions of 1-aryl-2-propyn-1-ones with primary amines
Um, Ik-Hwan,Lee, Eun-Ju,Seok, Jin-Ah,Kim, Kyung-Hee
, p. 7530 - 7536 (2007/10/03)
Second-order rate constants (kN) have been measured for the Michael-type reaction of 1-(X-substituted phenyl)-2-propyn-1-ones (2a-f) with a series of primary amines in H2O at 25.0 ± 0.1 °C. A linear Bronsted-type plot with a small βnuc value (βnuc = 0.30) has been obtained for the reactions of 1-phenyl-2-propyn-1-one (2c) with non-α-nucleophile amines. Hydrazine is more reactive than other primary amines of similar basicity (e.g., glycylglycine and glycine ethyl ester) and results in a positive deviation from the linear Bronsted-type plot. The reactions of 2a-f with hydrazine exhibit a linear Hammett plot, while those with non-α-nucleophile amines give linear Yukawa-Tsuno plots, indicating that the electronic nature of the substituent X does not affect the reaction mechanism. The α-effect increases as the substituent X in the phenyl ring of 2a-f becomes a stronger electron-donating group. However, the magnitude of the α-effect for the reactions of 2a-f is small (e.g., kNhydrazine/kN glycylglycine = 4.6-13) regardless of the electronic nature of the substituent X. The small βnuc has been suggested to be responsible for the small α-effect. A solvent kinetic isotope effect (e.g., kNH2O/kND2O = 1.86) was observed for the reaction with hydrazine but absent for the reactions with non-α-nucleophile amines. The reactions with hydrazine and other primary amines have been suggested to proceed through a five-membered intramolecular H-bonding structure VI and a six-membered intermolecular H-bonding structure VII, respectively. The transition state modeled on VI can account for the substituent dependent α-effect and the difference in the solvent kinetic isotope effect exhibited by the reactions with hydrazine and other primary amines. It has been proposed that the βnuc value is more important than the hybridization type of the reaction site to determine the magnitude of the α-effect.
Differential Reactivity of β-Amino Enones and 3-Dimethylaminoacrylaldehyde towards α-Amino Derivatives
Alberola, Angel,Andres, Jose M.,Gonzalez, Alfonso,Pedrosa, Rafael,Vicente, Martina
, p. 2681 - 2685 (2007/10/02)
Unsubstituted β-amino enones react with α-amino derivatives by a well established route with implies a fast transamination process - 1,4-addition followed by elimination - and cyclodehydration of the intermediate to 3-functionalized pyrroles.In contrast, 3-dimethylaminoacrylaldehyde undergoes 1,2-addition followed by cyclization to give the final 2-substituted pyrroles.Isolation of the intermediates supports the proposed mechanism for each reaction.
