Nucleophilic replacement of methoxyl in the reaction of a sterically hindered o-benzoquinone with o-phenylenediamine

1965 ◽  
Vol 18 (8) ◽  
pp. 1241 ◽  
Author(s):  
FR Hewgill ◽  
DG Hewitt ◽  
PB Langley
Keyword(s):  
Quinone Imine ◽  
Dilute Acid ◽  
Spectroscopic Evidence ◽  
Nucleophilic Replacement ◽  
Sterically Hindered

With o-phenylenediamine, 3-t-butyl-5-methoxy-l,2-benzoquinone gives the quinone imine (VII), but only a trace of the expected phenazine (II). Dilute acid converts (VII) to the anilinophenazine (III). Chemical and spectroscopic evidence for the structures of these compounds is presented.

Nickel-Catalyzed Regioselective Hydroalkylation of 1,3-Dienes with Hydrazones

2019 ◽  
Author(s):  
Leiyang Lv ◽  
Dianhu Zhu ◽  
Zihang Qiu ◽  
Jianbin Li ◽  
Chao-Jun Li
Keyword(s):  
Catalytic Method ◽  
Unsaturated Hydrocarbons ◽  
Carbon Nucleophiles ◽  
Aryl Aldehydes ◽  
Aldehydes And Ketones ◽  
Sterically Hindered

Hydroalkylation of unsaturated hydrocarbons with unstablized carbon nucleophiles is difficult and remains a major challenge. The disclosed examples so far mainly focused on the involvement of heteroatom and/or stabilized carbon nucleophiles as efficient reaction partners. Reported here is an unprecedented regioselective nickel-catalyzed hydroalkylation of 1,3-dienes with hydrazones, generated in situ from abundant aryl aldehydes and ketones and acted as both the sources of unstabilized carbanions and hydride. With this strategy, both terminal and sterically hindered internal dienes are hydroalkylated efficiently in a highly selective manner, thus providing a novel and reliable catalytic method to construct challenging C(sp3)-C(sp3) bonds.

Synthesis of Conjugated Triynes via Alkyne Metathesis

2019 ◽  
Author(s):  
Idriss Curbet ◽  
Sophie Colombel-Rouen ◽  
Romane Manguin ◽  
Anthony Clermont ◽  
Alexandre Quelhas ◽  
...  
Keyword(s):  
Steric Hindrance ◽  
High Selectivity ◽  
Alkyne Metathesis ◽  
Cross Metathesis ◽  
Synthetic Strategy ◽  
Sterically Hindered ◽  
Site Selective

<div> <div> <div> <div> <p>The synthesis of conjugated triynes by molybdenum-catalyzed alkyne metathesis is reported. Strategic to the success of this approach is the utilization of sterically-hindered diynes that allowed for the site- selective alkyne metathesis to produce the desired con- jugated triyne products. The steric hindrance of alkyne moiety was found to be crucial in preventing the for- mation of diyne byproducts. This novel synthetic strategy was amenable to self- and cross-metathesis providing straightforward access to the corresponding symmetrical and dissymmetrical triynes with high selectivity. </p> </div> </div> </div> </div>

NADH in Solution: A Single State

2019 ◽  
Author(s):  
Joachim Hönes ◽  
Julia Wack ◽  
Katja Schmitz
Keyword(s):  
Aqueous Solution ◽  
Base Stacking ◽  
Spectroscopic Evidence ◽  
Single State

<div>Spectroscopic evidence is presented to show that NADH in aqueous solution does not exist as a folded/unfolded equilibrium but as a single state. The molecule is folded but without base stacking between dihydronicotinamide and adenine.<br></div>

scholarly journals Dihydroflavonol and Flavonol Derivatives from Macaranga Recurvata

2012 ◽  
Vol 7 (10) ◽  
pp. 1934578X1200701
Author(s):  
Mulyadi Tanjung ◽  
Euis H. Hakim ◽  
Elfahmi ◽  
Jalifah Latip ◽  
Yana M. Syah
Keyword(s):  
Strong Activity ◽  
Spectroscopic Evidence ◽  
New Compounds ◽  
Flavonol Derivatives

Two new dihydroflavonol derivatives, macarecurvatins A and B, have been isolated from the leaves of Macaranga recurvata(Euphorbiaceaae), along with the known compounds diisoprenylaromadendrin, glyasperin A and broussoflavonol F. The structures of the new compounds were determined on the basis of spectroscopic evidence. Upon cytotoxic evaluation against P-388 cells, macarecurvatin B showed strong activity with an IC50 of 0.83 μM.

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