intermediary amino compounds are isolated. The reaction involves many reversible steps, and the stereochemistry of products is determined in the elimination step from the intermediary compounds via stable planar carbanions, in which the small difference in the steric requirements of two electron-withdrawing groups is effective. Steric and electronic effects in the intermediates sometimes bring about the
用催化量的仲胺处理活性亚甲基化合物和醛可产生热力学稳定的烯烃,并分离出中间
氨基化合物。该反应涉及许多可逆步骤,产物的立体
化学是在中间化合物通过稳定的平面碳负离子消除步骤中确定的,其中两个吸电子基团的空间要求的微小差异是有效的。中间体中的空间和电子效应有时会随着活性亚甲基化合物的回收而导致碳-碳键裂变,这些效应阻止了 Knoevenagel 反应的发生。