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
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
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.