Nitrobenzaldehyde thiosemicarbazone (C_8H_8N_4O_2S) has been prepared by the condensation of 4-nitrobenzaldehyde with thiosemicarbazide. This compound crystallized in monoclinic space group P2_1/c with the unit cell p...Nitrobenzaldehyde thiosemicarbazone (C_8H_8N_4O_2S) has been prepared by the condensation of 4-nitrobenzaldehyde with thiosemicarbazide. This compound crystallized in monoclinic space group P2_1/c with the unit cell parameters : a =4. 560(2), b=24. 900(4), c=8. 950(2) A, β=98. 37(2)°, V=1005. 2 A￣3, Z=4,D_c = 1. 482 g/cm￣3, λ= 0. 71073 A, μ(MoKα)=0. 293 mm￣(-1) , final R= 0.044 for 1568 observed reflections. Analvsis of molecular structure reveals that the molecule is in trans-configuration. The molecular packing is governed by N-H...S and O... H-N hydrogen bonding interactions.展开更多
DFT-B3LYP calculations were carried out to study the enantioselectivity of the （S）-4-hydroxylproline-catalyzed direct aldol reaction between acetone and 4-nitrobenzaldehyde. Four transition structures associated wit...DFT-B3LYP calculations were carried out to study the enantioselectivity of the （S）-4-hydroxylproline-catalyzed direct aldol reaction between acetone and 4-nitrobenzaldehyde. Four transition structures associated with the stereo-controlling step of the reaction have been determined. They are corresponding to the anti and syn arrangements of the methylene moiety related to the carboxylic acid group in enamine intermediate and the si and re attacks to the aldehyde carbonyl carbon. The effect of DMSO solvent on the stereo-controlling step was investigated with polarized continuum model （PCM）. The computed energies of the transition states reveal the moderate enantioselectivity of the reaction.展开更多
DFT/6-31G^＊ calculations were applied to study the direct aldol reaction between acetone and 4-nitrobenzaldehyde catalyzed by （S）-proline. Four transition states associated with the stereo-controlling step, corresp...DFT/6-31G^＊ calculations were applied to study the direct aldol reaction between acetone and 4-nitrobenzaldehyde catalyzed by （S）-proline. Four transition states associated with the stereo-controlling step, corresponding to syn and anti arrangements of methylene moiety related to the carboxylic acid group in enamine intermediate and re and si attacks to the aldehyde carbonyl carbon have been obtained. The solvent effect of DMSO was investigated with polarized continuum model. The computed energies of transition states reveal the stereo-selectivity of the reaction.展开更多
The benzylation and allylation of 4-nitrobenzaldehyde (1) could be controlled chemoselectively by using different phase transfer catalyst (FTC) and different metal catalysts. And then, benzylation and allylation of 1 ...The benzylation and allylation of 4-nitrobenzaldehyde (1) could be controlled chemoselectively by using different phase transfer catalyst (FTC) and different metal catalysts. And then, benzylation and allylation of 1 with various organic halides has been realized in high yields in aqueous media.展开更多
文摘Nitrobenzaldehyde thiosemicarbazone (C_8H_8N_4O_2S) has been prepared by the condensation of 4-nitrobenzaldehyde with thiosemicarbazide. This compound crystallized in monoclinic space group P2_1/c with the unit cell parameters : a =4. 560(2), b=24. 900(4), c=8. 950(2) A, β=98. 37(2)°, V=1005. 2 A￣3, Z=4,D_c = 1. 482 g/cm￣3, λ= 0. 71073 A, μ(MoKα)=0. 293 mm￣(-1) , final R= 0.044 for 1568 observed reflections. Analvsis of molecular structure reveals that the molecule is in trans-configuration. The molecular packing is governed by N-H...S and O... H-N hydrogen bonding interactions.
文摘DFT-B3LYP calculations were carried out to study the enantioselectivity of the （S）-4-hydroxylproline-catalyzed direct aldol reaction between acetone and 4-nitrobenzaldehyde. Four transition structures associated with the stereo-controlling step of the reaction have been determined. They are corresponding to the anti and syn arrangements of the methylene moiety related to the carboxylic acid group in enamine intermediate and the si and re attacks to the aldehyde carbonyl carbon. The effect of DMSO solvent on the stereo-controlling step was investigated with polarized continuum model （PCM）. The computed energies of the transition states reveal the moderate enantioselectivity of the reaction.
基金This project was supported by the Research Foundation of Key Laboratory of Organic Synthesis of Jiangsu Province (No. JSK010)
文摘DFT/6-31G^＊ calculations were applied to study the direct aldol reaction between acetone and 4-nitrobenzaldehyde catalyzed by （S）-proline. Four transition states associated with the stereo-controlling step, corresponding to syn and anti arrangements of methylene moiety related to the carboxylic acid group in enamine intermediate and re and si attacks to the aldehyde carbonyl carbon have been obtained. The solvent effect of DMSO was investigated with polarized continuum model. The computed energies of transition states reveal the stereo-selectivity of the reaction.
文摘The benzylation and allylation of 4-nitrobenzaldehyde (1) could be controlled chemoselectively by using different phase transfer catalyst (FTC) and different metal catalysts. And then, benzylation and allylation of 1 with various organic halides has been realized in high yields in aqueous media.
