- Synthesis of Quaternary α-Fluorinated α-Amino Acid Derivatives via Coordinating Cu(II) Catalytic α-C(sp3)-H Direct Fluorination
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A coordinating, copper-catalyzed direct α-C(sp3)-H fluorination method has been developed to prepare vital quaternary α-fluorinated α-amino acid derivatives. A Cu(II) catalytic SET oxidative addition mechanism is proposed, involving a key fluoride-coupled Cu(II) charge transfer complex. The protocol can tolerate a rich variety of α-amino acids, for which the auxiliary group is removed in high yield and substituted for the direct preparation of dipeptide derivatives with detachable, single absolute configurations of the target compounds.
- Wei, Qiang,Ma, Yao,Li, Li,Liu, Qingfei,Liu, Zijie,Liu, Gang
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supporting information
p. 7100 - 7103
(2018/11/24)
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- 1-Imidoalkylphosphonium salts with modulated Cα–P+ bond strength: synthesis and application as new active α-imidoalkylating agents
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An effective synthesis of the hitherto unknown 1-imidoalkylphosphonium salts has been developed in the reported study. The crucial step in the method included the decarboxylative α-methoxylation of N-phthaloyl- or N-succinylamino acids to the corresponding N-(1-methoxyalkyl)imides, followed by the displacement of the methoxy group by the triarylphosphonium group through melting of the imide derivative with triarylphosphonium tetrafluoroborate. The imidoalkylating properties of the obtained 1-imidoalkylphosphonium salts were tested using the Tscherniac–Einhorn-type reaction with aromatic hydrocarbons as a model reaction. It was found that the Cα–P+ bond strength can be considerably reduced and the imidoalkylation of arenes can be markedly facilitated using 1-imidoalkylphosphonium salts derived from triarylphosphines with electron-withdrawing substituents such as tris(m-chorophenyl)phosphine, tris(p-chlorophenyl)phosphine and tris[p-(trifluoromethyl)phenyl]phosphine. Microwave irradiation also considerably facilitates the cleavage of the highly polar Cα–P+ bond.
- Adamek, Jakub,Mazurkiewicz, Roman,W?grzyk, Anna,Erfurt, Karol
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supporting information
p. 1446 - 1455
(2017/08/02)
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- Design, synthesis and mechanism of novel shikonin derivatives as potent anticancer agents
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In this study, a series of novel shikonin derivatives (30-49) were designed and synthesized and their anti-proliferative activities were evaluated against five different cancer cell lines, including HeLa, HepG2, MCF-7, BGC and A549. Some of the compounds show strong anti-proliferative effects against HeLa, HepG2 and MCF-7 with IC50 values ranging from 1.26 to 18.50 μM and show lower side effects towards normal cell lines as compared to shikonin. Compared to other compounds and shikonin itself, compound 40 displayed much stronger anti-proliferative effects against various cancer cell lines. Furthermore, the flow cytometry results demonstrated that compound 40 could obviously induce apoptosis in a dose- and time-dependent manner and also cause cell cycle arrest at the G2/M phase. For further investigation of the aforementioned mechanisms, we performed Western blot experiments and found that the cleavage of PARP and upstream caspase-3 increased; moreover, caspase-9 was activated by cleavage but not caspase-8. These aforementioned results also indicate that compound 40 could induce caspase-9 involved apoptosis and G2/M phase cell cycle arrest via the P21, p-CDC2 (Tyr15) pathway independent of P53.
- Baloch, Shahla Karim,Ma, Lin,Wang, Xue-Liang,Shi, Jing,Zhu, Yu,Wu, Feng-Yao,Pang, Yan-Jun,Lu, Gui-Hua,Qi, Jin-Liang,Wang, Xiao-Ming,Gu, Hong-Wei,Yang, Yong-Hua
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p. 31759 - 31767
(2015/04/22)
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- NOVEL POLY(ARALKYL KETONE)S AND METHODS OF PREPARING THE SAME
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Disclosed are processes for preparing modifiable poly(aralkyl ketone)s having active methylene group(s) in the main chain comprising reacting an aralkanoic acid or mixtures thereof in the presence of one alkane or aryl sulfonic acid and a condensing agent. Also disclosed are novel modifiable poly(aralkyl ketone)s obtainable by the processes of the inventions.
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Page/Page column 10
(2010/02/14)
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