The rapid alkylation of methyl N-benzylidene glycinate with halides under microwave irradiation using solid-liquid phase transfer condition without solvent has been achieved wilhin only one minute. After hydrolysis of...The rapid alkylation of methyl N-benzylidene glycinate with halides under microwave irradiation using solid-liquid phase transfer condition without solvent has been achieved wilhin only one minute. After hydrolysis of alkylated products the corresponding α-amino acids were obtained in overall yield 43.6～62.5%.展开更多
The effects of two different amino acid catalysts on the stereoselectivities in the direct Mannich reactions of cyclohexanone,p-anisidine and p-nitrobenzaldehyde were studied with the aid of density functional theory....The effects of two different amino acid catalysts on the stereoselectivities in the direct Mannich reactions of cyclohexanone,p-anisidine and p-nitrobenzaldehyde were studied with the aid of density functional theory.Transition states of the stereo-determining C ＂C bond-forming step with the addition of enamine intermediate to the imine for the L-proline（·-amino acid） and （R）-3-pyrrolidinecarboxylic acid（·-amino acid）-catalyzed processes were reported.B3LYP/6-31G calculations provide a good explanation for the opposite syn vs.anti diastereoselectivities of these two different kinds of catalysts（syn-selectivity for the ·-amino acid catalysts,anti-selectivity for the ·-amino acid catalysts）.Calculated and observed diastereomeric ratio and enantiomeric excess values are in reasonable agreement.展开更多
文摘The rapid alkylation of methyl N-benzylidene glycinate with halides under microwave irradiation using solid-liquid phase transfer condition without solvent has been achieved wilhin only one minute. After hydrolysis of alkylated products the corresponding α-amino acids were obtained in overall yield 43.6～62.5%.
基金Supported by the National Natural Science Foundation of China(Nos.20773071,20901043)the Natural Science Foundation of Shandong Province,China(No.ZR2010BM024)the Project of Shandong Province Higher Educational Science and Technology Program,China(No.J10LB06)
文摘The effects of two different amino acid catalysts on the stereoselectivities in the direct Mannich reactions of cyclohexanone,p-anisidine and p-nitrobenzaldehyde were studied with the aid of density functional theory.Transition states of the stereo-determining C ＂C bond-forming step with the addition of enamine intermediate to the imine for the L-proline（·-amino acid） and （R）-3-pyrrolidinecarboxylic acid（·-amino acid）-catalyzed processes were reported.B3LYP/6-31G calculations provide a good explanation for the opposite syn vs.anti diastereoselectivities of these two different kinds of catalysts（syn-selectivity for the ·-amino acid catalysts,anti-selectivity for the ·-amino acid catalysts）.Calculated and observed diastereomeric ratio and enantiomeric excess values are in reasonable agreement.
