72725-79-2Relevant academic research and scientific papers
Selectivity in the Metalation of Polymethylpyrazines
Bassfield, Ronald L.,Houminer, Yoram
, p. 2130 - 2133 (1983)
The selectivity in the LDA-promoted lithiation of 2,3,5-trimethylpyrazine was studied by using the perdeuterated substrate 1-d9.Quenching of the lithium salts of the latter with H2O gave a 1-d8 isomer mixture which was analyzed by NMR.The order of reactivity of the three CH3 groups in 1-d9 was found to be 3 > 2 > 5.The metalation studies were extended also to isomeric dimethylpyrazines.It was established that the two ortho CH3 groups in 2,3-dimethylpyrazine are more easily metalated than either of the CH3 groups in the other isomeric dimethylpyrazines.
Studies on the Thermolysis of 2-(2-Hydroxy-2-arylethyl)pyrazines. An Example of a Retro-Ene-Type Reaction
Houminer, Yoram
, p. 999 - 1003 (2007/10/02)
Several substituted 2-(2-hydroxy-2-arylethyl)pyrazines (1-10) have been prepared and their thermolysis in diglyme and DMF studied.Each of these substrates decomposes to give the parent methylpyrazine and the corresponding aryl aldehyde.Kinetic, isotope effect, and solvent effect studies suggest a mechanism involving a nonpolar concerted six-membered-ring transition state.The degree of proton transfer in the transition state is discussed in detail.Methyl substituents on the pyrazine ring were found to strongly affect the reaction rate.This phenomenon is analyzed interms of the steric and electronic effects induced by the methyl substituents.
