Concise Synthesis and Evaluation of ortho-Naphthoquinones Containing a Phenolic Hydroxy Moiety

Heterocycles ◽  
2020 ◽  
Vol 100 (2) ◽  
pp. 225
Author(s):  
Akira Iida ◽  
Mitsuaki Yamashita ◽  
Syuhei Hata ◽  
Jun Sawano ◽  
Ryuji Umeda
Keyword(s):  
Phenolic Hydroxy

Candida antarctica lipase B-catalyzed regioselective deacylation of dihydroxybenzenes acylated at both phenolic hydroxy groups

2016 ◽  
Vol 94 (1) ◽  
pp. 44-49 ◽  
Author(s):  
Toshifumi Miyazawa ◽  
Manabu Hamada ◽  
Ryohei Morimoto
Keyword(s):  
Candida Antarctica ◽  
Candida Antarctica Lipase B ◽  
Candida Antarctica Lipase ◽  
Primary Alcohols ◽  
Lipase B ◽  
Highly Active ◽  
Direct Acylation ◽  
Acyl Acceptors ◽  
Hydroxy Groups ◽  
Phenolic Hydroxy

Candida antarctica lipase B proved to be highly active in the deacylation of substituted hydroquinones and resorcinols acylated at both phenolic hydroxy groups. The deacylation reactions were much faster than the corresponding direct acylations of these dihydroxybenzenes catalyzed by the same lipase. More importantly, they took place generally in a markedly regioselective manner: the acyloxy group remote from the substituent was preferentially cleaved. The main or exclusive products obtained were the regioisomers of those produced through the direct acylation of the dihydroxybenzenes. In the case of alkyl-substituted hydroquinone derivatives, the regioselectivity increased with an increase in the bulk of the substituent. In the case of 4-substituted diacylated resorcinols, the 3-O-monoacyl derivatives were obtained generally as the sole products. Quite interestingly, some secondary alcohols proved to act as better acyl acceptors than the corresponding primary alcohols in these enzymatic deacylations.

Enzymatic Sulfation of Phenolic Hydroxy Groups of Various Plant Metabolites by an Arylsulfotransferase

2014 ◽  
Vol 2015 (3) ◽  
pp. 534-541 ◽  
Author(s):  
Michael A. van der Horst ◽  
Aloysius F. Hartog ◽  
Rabab El Morabet ◽  
Arthur Marais ◽  
Menzo Kircz ◽  
...  
Keyword(s):  
Plant Metabolites ◽  
Hydroxy Groups ◽  
Phenolic Hydroxy

A New Type of Double Calix[4]arenes by Linkage via the Phenolic Hydroxy Groups

1990 ◽  
Vol 29 (3) ◽  
pp. 280-282 ◽  
Author(s):  
M. Anthony McKervey ◽  
Michael Owens ◽  
Hans-Rolf Sehulten ◽  
Walter Vogt ◽  
Volker Böhmer
Keyword(s):  
New Type ◽  
Hydroxy Groups ◽  
Phenolic Hydroxy

Superoxide Anion Scavenging Effect of Coumarins

1996 ◽  
Vol 24 (01) ◽  
pp. 11-17 ◽  
Author(s):  
Wen-Shin Chang ◽  
Chun-Ching Lin ◽  
Shu-Chuan Chuang ◽  
Hsuch-Ching Chiang
Keyword(s):  
Cytochrome C ◽  
Xanthine Oxidase ◽  
Superoxide Anion ◽  
Folk Medicine ◽  
Ortho Position ◽  
Scavenging Activity ◽  
Percent Inhibition ◽  
Scavenging Effect ◽  
Hydroxy Groups ◽  
Phenolic Hydroxy

The superoxide scavenging effects of fifteen coumarins were tested on the xanthine-xanthine oxidase-cytochrome C system. The results showed that fraxetin(10) displayed the strongest activity, and its percent inhibition at 100, 10 and 1 μM were 100, 100 and 53.13% respectively. Esculetin(4) showed the second strongest activity resulting in percent inhibition at 100 and 10 μM were 87.16 and 52.38% respectively. Both fraxetin(10) and esculetin(4) have been isolated from the plant, Fraxinus bungeana DC (Oleaceae) which has been used in folk medicine as an analgesic and anti-inflammatory medicine. It seems that two phenolic hydroxy groups in the ortho position in the molecule of coumarins play an important role in scavenging activity.

Anion Recognition by 1,3-Benzenedisulfonamide Derivatives Bearing Phenolic Hydroxy Groups in MeCN-d3

2005 ◽  
Vol 78 (7) ◽  
pp. 1348-1350 ◽  
Author(s):  
Shin-ichi Kondo ◽  
Takashi Suzuki ◽  
Takuya Toyama ◽  
Yumihiko Yano
Keyword(s):  
Anion Recognition ◽  
Hydroxy Groups ◽  
Phenolic Hydroxy

Determination of the substituent constant σp- for the thioamide group -CSNH2 from the ionization of anilines and phenols

1991 ◽  
Vol 56 (12) ◽  
pp. 2964-2968 ◽  
Author(s):  
Miroslav Polášek ◽  
Karel Waisser ◽  
Tomáš Bouček
Keyword(s):  
Ultra Violet ◽  
Ionization Constants ◽  
Amino Group ◽  
Substituted Phenols ◽  
Substituent Constant ◽  
Substituted Anilines ◽  
Phenolic Hydroxy Group ◽  
Thioamide Group ◽  
Phenolic Hydroxy

Thermodynamic ionization constants pKa 2.62 ± 0.01 for the primary aromatic amino group of 4-aminothiobenzamide and pKa 8.28 ± 0.01 for the phenolic hydroxy group of 4-hydroxythiobenzamide have been determined by ultra-violet spectrophotometry at 25°C. By using these pKa values and the Hammett equations (log Ka vs σ) for the ionization of fourteen 3- or 4-substituted phenols and thirteen 3- or 4-substituted anilines the substituent constant σp- = 0.68 (from the ionization of anilines) or σp- = 0.73 (from the ionization of phenols) of the thioamide group -CSNH2 was calculated.

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