First Synthesis of a Pentasaccharide Moiety of Ganglioside GAA-7 Containing Unusually Modified Sialic Acids through the Use of N-Troc-sialic Acid Derivative as a Key Unit
摘要:
The pentasaccharide part of the potent neuritogenic ganglioside GAA-7 has been synthesized for the first time. The unique branched terminus constituting partially modified sialic acids and N-acetylgalactosamine was successfully established by stereoselective double-sialylation using 8-O-methyl-N-Troc-sialic acid as a donor. The final 4 + 1 coupling reaction provided a high yield of pentasaccharide, which was deprotected to deliver the target molecule.
Facile Preparation of 2-Imino-1,3-selenazolidin-4-one Derivatives by Reaction of <b><i>N</i></b>,<b><i>N’</i></b>-Disubstituted Selenoureas with α-Haloacyl Halides
作者:Mamoru Koketsu、Hideharu Ishihara、Futoshi Nada
DOI:10.1055/s-2002-19800
日期:——
2-Imino-1,3-selenazolidin-4-one derivatives were synthesized by the reaction of N,N'-disubstituted selenoureas with u-haloacyl halides in the presence of pyridine.
PREPARATION AND CHARACTERISATION OF <i>N,N</i>-DISUBSTITUTED 2-AMINO-SELENAZOLES
作者:Dietmar Keil、Horst Hartmann
DOI:10.1080/10426509908031628
日期:1999.9.1
Abstract As a result of checking suited methods for preparing N,N-disubstituted 2-amino-selenazoles 14 as a nearly unknown class of highly reactive selenazoles a simple route starting from N,N-disubstituted selenoureas 12 has been elaborated and used for the synthesis of a series of these compounds. The necessary selenium-containing starting compounds 12 are available from N,N-disubstituted cyanamides
Synthesis of 2-Amino-1,3-selenazoles by Reaction of N,N-Unsubstituted Selenoureas with a,b-Unsaturated Aldehydes
作者:Mamoru Koketsu、Koichi Kanoh、Hideharu Ishihara
DOI:10.3987/com-06-10893
日期:——
2-Dialkylamino-l,3-selenazoles were obtained by the reaction of N,N-unsubstitutedselenoureas with α,β-unsaturated aldehydes in alcohol in the presence of ferric chloride at room temperature.
2-二烷基氨基-1,3-硒唑是由N,N-未取代的硒脲与α,β-不饱和醛在氯化铁存在下室温反应得到。
A Simple Route to <i>N</i>,<i>N</i>-Disubstituted Selenoureas from N,N-Disubstituted Cyanamides
作者:Horst Hartmann、Dietmar Keil
DOI:10.1055/s-2003-44349
日期:——
N,N-Disubstituted selenoureas 4 can be obtained in satisfactory yields by addition of an acid to a mixture of freshly prepared sodium selenide and N,N-disubstituted cyanamides 5.
This study investigated inhibitory effects of N,N-unsubstituted selenourea derivatives on tyrosinase activity. Three types of N,N-unsubstituted selenoureas derivatives exhibited inhibitory effect on dopa (3,4-dihydroxyphenylalanine) oxidase activity of mushroom tyrosinase. Compound D at a concentration of 200 μM exhibited 55.5% of inhibition on dopa oxidase activity of mushroom tyrosinase. This inhibitory effect was higher than that of kojic acid (39.4%), a well known tyrosinase inhibitor. Moreover, the compound D identified as a noncompetitive inhibitor by Lineweaver–Burk plot analysis. In addition, compound D also inhibited the melanin production in melan-a cells.
本研究探讨了 N,N-未取代硒脲衍生物对酪氨酸酶活性的抑制作用。三种 N,N-未取代硒脲衍生物对蘑菇酪氨酸酶的多巴(3,4-二羟基苯丙氨酸)氧化酶活性有抑制作用。浓度为 200 μ<小>M小>的化合物 D 对蘑菇酪氨酸酶多巴氧化酶活性的抑制率为 55.5%。这种抑制效果高于众所周知的酪氨酸酶抑制剂曲酸(39.4%)。此外,化合物 D 通过 Lineweaver-Burk plot 分析被确定为一种非竞争性抑制剂。此外,化合物 D 还能抑制黑色素-a 细胞中黑色素的生成。