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One-pot, three-component approach to diarylacetonitriles
Singh, Dileep Kumar,Prasad, Sure Siva,Kim, Jinhwang,Kim, Ikyon The Royal Society of Chemistry 2019 ORGANIC CHEMISTRY FRONTIERS Vol.6 No.5
<P>Described herein is a novel one-pot, three-component reaction where aldehydes, electron-rich arenes, and TMSCN in the presence of BF3-OEt2 allowed direct access to a number of diarylacetonitriles under mild reaction conditions in good to excellent yields. Implementation of this assembly protocol to a concise synthetic approach to shoreaphenol, a bioactive oligostilbenoid natural product, is also demonstrated.</P>
Skeletal Reorganization: Synthesis of Diptoindonesin G from Pauciflorol F
Singh, Dileep Kumar,Kim, Ikyon American Chemical Society 2018 Journal of organic chemistry Vol.83 No.3
<P>Described herein is a novel synthetic approach to diptoindonesin G, a highly potent anticancer oligostilbenoid natural product, from pauciflorol F pentamethyl ether through a skeletal reorganization strategy where oxidative cleavage of the indanone ring system of pauciflorol F and sequential cyclization of the key intermediate allowed direct access to the target skeleton.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/joceah/2018/joceah.2018.83.issue-3/acs.joc.7b03089/production/images/medium/jo-2017-03089y_0007.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/jo7b03089'>ACS Electronic Supporting Info</A></P>
Convergent synthesis of diptoindonesin G
Singh, Dileep Kumar,Kim, Ikyon Elsevier 2019 Tetrahedron letters: the international organ for t Vol.60 No.3
<P><B>Abstract</B></P> <P>A convergent and scalable synthetic route to a tetracyclic oligostilbenoid natural product, diptoindonesin G, is described where Suzuki-Miyaura cross-coupling and intramolecular Friedel-Crafts acylation were employed to construct the central C ring of diptoindonesin G. Two fragments for cross-coupling reaction were readily synthesized with similar efficiency.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A convergent and scalable synthetic approach to diptoindonesin G is described. </LI> <LI> Suzuki-Miyaura coupling and intramolecular Friedel-Crafts acylation as key steps. </LI> <LI> This route should be useful for synthesis of diptoindonesin G and its derivatives. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Dileep Kumar Singh,김진우,성종혁,김익연 대한화학회 2018 Bulletin of the Korean Chemical Society Vol.39 No.2
Biological screening of the natural products from Dalbergia oliveri identified that (6aR,11aR)-3,8-dihydroxy-9-methoxypterocarpan and (3R)-7,2′-dihydroxy-4′,5′-dimethoxyisoflavanone significantly increased the proliferation of dermal papilla cells and subcutaneous injection of these compounds induced the anagen of hair cycle in animal models. These interesting biological activities led us to design a practical synthetic route to these natural products for further pharmacological evaluation. Here we report the first total syntheses of naturally occurring pterocarpan ((6aR,11aR)-3,8-dihydroxy-9-methoxypterocarpan), isoflavan ((3R)-5′-methoxyvestitol), and isoflavanone ((3R)-7,2′-dihydroxy-4′,5′-dimethoxyisoflavanone) in a racemic form. A mild ZnCl2-mediated [3 + 2] annulation method was utilized with chromenes and 2-methoxy-1,4-benzoquinone to construct a pterocarpan framework in a one-pot manner. O-methylation and reductive cleavage of the benzylic C─O bond afforded 5′-methoxyvestitol, which was transformed to isoflavanone, 7,2′-dihydroxy-4′,5′-dimethoxyisoflavanone, via a three-step sequence including DDQ-mediated benzylic oxidation.
Nayak, Maloy,Singh, Dileep Kumar,Kim, Ikyon Elsevier 2017 Tetrahedron Vol.73 No.14
<P><B>Abstract</B></P> <P>A modular approach to 5-acylated naphtho[2,1-<I>b</I>]benzofurans was developed where Sonogashira cross-coupling and intramolecular alkyne carbonyl metathesis were sequentially employed to build the aromatic benzene C ring of naphtho[2,1-<I>b</I>]benzofuran with an acyl group at the C5 position.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Prasad, Sure Siva,Singh, Dileep Kumar,Kim, Ikyon American Chemical Society 2019 Journal of organic chemistry Vol.84 No.10
<P>A new type of three-component reaction was developed consisting of aldehydes, electron-rich (hetero)arenes, and trialkyl phosphite, which provided facile access to a wide range of diarylmethylphosphonates under mild reaction conditions. Simple one- or two-step synthetic manipulation of the resulting compounds enabled us to reach several polycyclic (hetero)aromatic systems efficiently.</P> [FIG OMISSION]</BR>
Design, synthesis, and biological evaluation of novel pyrrolo[1,2-<i>a</i>]pyrazine derivatives
Kim, Jinwoo,Park, Mikyung,Choi, Jiwon,Singh, Dileep Kumar,Kwon, Ho Jeong,Kim, Seong Hwan,Kim, Ikyon Elsevier 2019 Bioorganic & medicinal chemistry letters Vol.29 No.11
<P><B>Abstract</B></P> <P>A pyrrolo[1,2-<I>a</I>]pyrazine-based chemical territory was expanded via construction of new chemical library with distinctive substitution patterns, which was made possible by regiodivergent electrophilic acylation followed by aldol condensation. Biological screening of the compounds in this class revealed that the viability of human lymphoma U937 cells was strongly inhibited by <B>6b</B> with a methoxy group at the <I>o</I>-position of the aromatic ring, but not by compounds <B>6t-w</B> bearing a halogen at the <I>o</I>-position. Furthermore, <B>6x</B> having a 2,4-dimethoxyphenyl group inhibited the survival of U937 cells more potently than <B>6b</B>. In contrast, <B>6y</B> possessing a 2,5-dimethoxyphenyl moiety did not show effective inhibition, implying the importance of orientation of the substituent(s) around the benzene ring. The anticancer action of <B>6x</B> with safe therapeutic window could be associated with the FTase-p38 signaling axis.</P> <P><B>Highlights</B></P> <P> <UL> <LI> New pyrrolo[1,2-<I>a</I>]pyrazine-based chemical space via regiodivergent acetylation/formylation followed by aldol condensation. </LI> <LI> Installation of a chalcone unit around the basic pyrrolo[1,2-<I>a</I>]pyrazine in a different orientation. </LI> <LI> Anticancer screening of the synthesized pyrrolo[1,2-<I>a</I>]pyrazine-chalcone hybrids. </LI> <LI> Identification of structural requirement of pyrrolo[1,2-<I>a</I>]pyrazine-chalcone skeleton to inhibit human lymphoma U937 cells. </LI> <LI> Anticancer activity of <B>6x</B> via the caspase-dependent apoptosis. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>