A general and efficient Pd/phosphoramidite thioether complex-catalyzed asymmetric N-allylic alkylation of hydrazones with allylicacetates has been developed for the first time. The reaction allows for the preparation of various valuable N-substituted hydrazones with generally good yields and excellent enantioselectivities. Minor structural modification of the ligand resulted in opposite enantiomers
Triazine-Substituted and Acyl Hydrazones: Experiment and Computation Reveal a Stability Inversion at Low pH
作者:Kun Ji、Changsuk Lee、Benjamin G. Janesko、Eric E. Simanek
DOI:10.1021/acs.molpharmaceut.5b00205
日期:2015.8.3
the series (aromaticaldehyde < aromatic ketone < aliphatic ketone). Computational and experimental studies indicate a reversal in stability around the triazine pKa (pH ∼5). Protonation of the triazine moiety retards acid-catalyzedhydrolysis of triazinyl hydrazones in comparison to acetyl hydrazone analogues. This behavior supports mechanistic interpretations suggesting that resistance to protonation
肼取代的s-三嗪与醛或酮的缩合产生与广泛使用的对酸不稳定的酰基的等同物。使用HPLC监测,使用甲醛捕集器水解这些azo,发现三嗪取代的hydr在pH> 5时比乙酰更不稳定。反应性趋势反映了相应的乙酰azo的反应趋势,水解速率沿系列增加(芳族醛<芳香族酮<脂肪族酮)。计算和实验研究表明三嗪p K a周围稳定性的逆转(pH〜5)。与乙酰类似物相比,三嗪部分的质子化阻碍了三嗪基的酸催化水解。此行为支持机械学解释,表明N N1的质子化抗性是影响反应速率的关键因素。
Synthesis of pyrazolines by a site isolated resin-bound reagents methodology
achieved by an organocatalysed aza-Michael/transimination domino sequence between hydrazones and enones making use of a mixture of heterogeneous resin-bound acid/base reagents. This methodology nicely illustrates the site isolation concept of supported reagents allowing the simultaneous use of otherwise destructive reactive functionalities.
Unexpected synthesis of 1,3,5-triarly-1,5-diketones from aryl ketones via di-enamine mechanism
作者:Bin Liu、Junfeng Wang、Yi Pang、Zemei Ge、Runtao Li
DOI:10.1016/j.tet.2014.10.009
日期:2014.12
An unexpected reaction of arylketone with acetohydrazone of aromatic aldehyde via 1,2-di-enamine/di-iminium mechanism was discovered, leading to efficient synthesis of 1,3,5-triaryl-1,5-diketones in good to excellent yields.
Anticonvulsant properties of various acetylhydrazones, oxamoylhydrazones and semicarbazones derived from aromatic and unsaturated carbonyl compounds
作者:Jonathan R Dimmock、Sarvesh C Vashishtha、James P Stables
DOI:10.1016/s0223-5234(00)00123-9
日期:2000.2
Various acetylhydrazones, oxamoylhydrazones and semicarbazones were prepared as candidate anticonvulsants with a view to examining the viability of a putative binding site hypothesis. Atomic charge calculations were undertaken to determine the hydrogen bonding capacities of various molecules. The biological results obtained revealed that in general the acetylhydrazones and semicarbazones afforded good