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Author: Hon Wai Lam
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Author: Hon Wai Lam
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Author: Joseph Samuel Ward
Publisher:
ISBN:
Category : Amphidinolida A
Languages : en
Pages : 396
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Author: Lamont R. Terrell
Publisher:
ISBN:
Category :
Languages : en
Pages : 530
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Author: Liang Lu
Publisher:
ISBN:
Category : Marine natural products
Languages : en
Pages : 786
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The structural architecture present in marine toxin azaspiracid - 20 stereocenters, 9 rings, 3 separated spirocenters - has attracted considerable synthetic attention. Our efforts toward the synthesis of azaspiracid have led to the completion of both C1-C26 northern and C27-C40 southern halves. Herein, the synthesis of southern FGHI ring system is described. The key steps included an Andrus anti-aldol coupling to furnish the C32, C33 stereocenters, an acid-catalyzed ketalization to furnish FG rings, and a Yb(OTf)3-mediated spiroaminal formation to generate I ring. The first total synthesis of cytotoxic macrolides amphidinolide B1 and the proposed structure of amphidinolide B2 have been accomplished. The key developed protocols include a metal catalyst-free sequence for the synthesis of the diene subunit, a non-chelation-controlled aldol coupling to install the C18 stereocenter, an efficient macrocyclization of the 26-membered lactone ring, and the incorporation of the labile allylic epoxide moiety. The unique structure of the highly substituted diene functionality represents significant synthetic challenges. A Wittig / HWE reaction sequence yielded the C13-C15 diene moiety in good yield in excellent diastereoselectivity. Subsequent Sharpless epoxidation and Red-Al-mediated regionselective epoxide opening gave the C16 tertiary alcohol. The protecting groups on C21 were discovered to have significant effects on the aldol reaction between C9-C18 aldehyde and C19-C25 methyl ketone. Although chelating groups such as PMB, Bn afforded 18S isomer as a single diastereomer, the removal of these groups has proven problematic. Non-chelating silyl group generated 18R isomer in 8:1 dr at -100°C, while the 18S stereomer was obtained at -40°C in 1.2:1 dr. A spontaneous intramolecular Wadsworth-Emmons olefination established the 26-membered macrocycle. The oxidation and in situ elimination of a selenide moiety proceeded smoothly in the presence of free alcohols using TMSOOTMS. The first total synthesis of amphidinolide B1 and the proposed structure of amphidinolide B2 were accomplished in 29 linear steps. Additionally, We discovered that the initially proposed structure of amphidinolide B2 was incorrect.
Author: William E. Brenzovich (Jr.)
Publisher:
ISBN:
Category : Antineoplastic agents
Languages : en
Pages : 916
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Author: Jonah James Chang
Publisher:
ISBN:
Category :
Languages : en
Pages : 346
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Author: Valerian Dragutan
Publisher: Springer Science & Business Media
ISBN: 9048134315
Category : Science
Languages : en
Pages : 432
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An outstanding international scientific event in the field of metathesis chemistry, the NATO ASI "Green Metathesis Chemistry: Great Challenges in Synthesis, Catalysis and Nanotechnology" has been recently organized in Bucharest, Romania (July 21- August 2, 2008). Numerous renowned scientists, young researchers and students, convened for two weeks to present and debate on the newest trends in alkene metathesis and identify future perspectives in this fascinating area of organic, organometallic, catalysis and polymer chemistry with foreseen important applications in materials science and technology. Following the fruitful practice of NATO Advanced Study Institutes, selected contributions covering plenary lectures, short communications and posters have been compiled in this special volume dedicated to this successful convention on green metathesis chemistry. General interest was primarily focused on relevant "green chemistry" features related to all types of metathesis reactions (RCM, CM, enyne metathesis, ADMET and ROMP). Diverse opportunities for green and sustainable technologies and industrial procedures based on metahesis have been identified. Largely exemplified was the utility of this broadly applicable strategy in organic synthesis, for accessing natural products and pharmaceuticals, and also its ability to fit in the manufacture of smart and nanostructured materials, self-assemblies with nanoscale morphologies, macromolecular engineering.
Author: Eric Marsault
Publisher: John Wiley & Sons
ISBN: 1119092566
Category : Science
Languages : en
Pages : 617
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Including case studies of macrocyclic marketed drugs and macrocycles in drug development, this book helps medicinal chemists deal with the synthetic and conceptual challenges of macrocycles in drug discovery efforts. Provides needed background to build a program in macrocycle drug discovery –design criteria, macrocycle profiles, applications, and limitations Features chapters contributed from leading international figures involved in macrocyclic drug discovery efforts Covers design criteria, typical profile of current macrocycles, applications, and limitations
Author: Andrew Frederick Nolting
Publisher:
ISBN:
Category :
Languages : en
Pages : 194
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Author: Min Hu
Publisher:
ISBN:
Category :
Languages : en
Pages : 384
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