Synthesis of 9-Acetyl-8,9-diaza-1-phosphabicyclo[4.3.0]nona-3,7-dienes by Regioselective Diels-Alder Reaction of 2H-1,2,3-Diazaphospholes with Isoprene
Synthesis of Isoquinoline Derivatives via Palladium‐Catalyzed C−H/C−N Bond Activation of
<i>N</i>
‐Acyl Hydrazones with
<i>α</i>
‐Substituted Vinyl Azides
A palladium‐catalyzed cyclization of N‐acetyl hydrazones with vinyl azides has been developed. Various substituted isoquinolines, including diverse fused isoquinolines can be prepared via this protocol in moderate to good yields. Mechanistic studies suggest that α‐substituted vinyl azide serves as an internal nitrogen source. Also, C−H bond activation and C−N bond cleavage have been realized using
N-Unsubstituted hydrazones of somearomaticketones and aldehydes were found to react with lead tetraacetate giving the corresponding diazo compounds as primary reaction products, and the derived 1-monoacetoxy- and 1,1-diacetoxy-1-arylalkanes, as well as azines, as final products. The yields obtained depend on the stability of the diazo compound initially formed and on the experimental conditions employed
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。
Catalytic asymmetric reductive amination of ketones via highly enantioselective hydrogenation of the CN double bond
作者:Mark J. Burk、Jose P. Martinez、John E. Feaster、Nick Cosford
DOI:10.1016/s0040-4020(01)89375-3
日期:1994.4
a convenient, chemoselective asymmetric reductive amination procedure for the conversion of ketones to chiral hydrazines and amines. The key step in the three-step process is enantioselective DuPHOS-Rh-catalyzed hydrogenation of the CN double bond of N-acylhydrazones. Detailed optimization studies revealed the effect of solvent, temperature, and the N-acyl group on the enantioselectivity and catalytic
Nickel-Catalyzed Asymmetric Transfer Hydrogenation of Hydrazones and Other Ketimines
作者:Haiyan Xu、Peng Yang、Pratanphorn Chuanprasit、Hajime Hirao、Jianrong Steve Zhou
DOI:10.1002/anie.201501018
日期:2015.4.20
We report the use of nickel catalysts for the catalytic transferhydrogenation of hydrazones and otherketimines with formic acid. Strongly donating bisphosphines must be used to support the catalysts. As in enzymatic catalysis, attractive weak interactions may be important for stereochemical control by the nickel/binapine catalyst.