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。
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
Harnessing Autoxidation of Aldehydes: <i>In Situ</i> Iodoarene Catalyzed Synthesis of Substituted 1,3,4-Oxadiazole, in the Presence of Molecular Oxygen
作者:Jyoti Chauhan、Mahesh K Ravva、Subhabrata Sen
DOI:10.1021/acs.orglett.9b02542
日期:2019.8.16
Isobutyraldehyde underwent auto-oxidation in the presence of molecular oxygen to generate an acyloxy radical under a “metal-free” environment. They were subsequently exploited in situ to afford hypervalent iodines with p-anisolyl iodide which generated substituted 1,3,4-oxadiazoles in moderate to excellent yields from N′-arylidene acetohydrazides. The reaction strategy tolerated diverse substitution
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。