Total Synthesis of the Chlorine‐Containing Hapalindoles K, A, and G

Chandra, Aroop; Johnston, Jeffrey N.

doi:10.1002/anie.201100957

Cited by 41 publications

(16 citation statements)

References 32 publications

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“…The Baran group achieved the total synthesis of a number of hapalindole alkaloids by using copper mediated unique oxidative coupling protocol –. Syntheses of hapalindole K, A and G were also achieved by the Johnston group . Very recently Zhou and co‐workers reported total syntheses of (+)‐hapalindole Q and (+)‐12‐ epi ‐fischerindole U isothiocyanate using the dynamic kinetic resolution (DKR) method .…”

Section: Figurementioning

confidence: 99%

Enantiospecific Total Syntheses of (+)‐Hapalindole H and (−)‐12‐epi‐Hapalindole U

Dethe

Das

Kumar

et al. 2018

Chemistry A European J

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Enantiospecific total syntheses of (+)-hapalindole H and (-)-12-epi-hapalindole U as well as the formal syntheses of (+)-hapalindole Q and (+)-12-epi-fischerindole U isothiocyanate have been described. Key steps of our approach feature expedient, highly regio- and diastereoselective Lewis acid catalyzed Friedel-Crafts reaction of indole with cyclic allylic alcohols and intramolecular reductive Heck reaction. Efficiency of the synthetic route also relies on an alkynyl aluminate complex driven regioselective nucleophilic epoxide opening from a sterically hindered site.

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Section: Figurementioning

confidence: 99%

Enantiospecific Total Syntheses of (+)‐Hapalindole H and (−)‐12‐epi‐Hapalindole U

Dethe

Das

Kumar

et al. 2018

Chemistry A European J

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“…Hapalindole formamides have been described as intermediates during the total synthesis of hapalindoles, as derivatization products with formic acid, and they can also form during storage in dchloroform [13,31,32,38]. Here, we report for the first time the isolation of 2 hapalindole formamides as natural products from Hapalosiphon sp.…”

Section: Resultsmentioning

confidence: 85%

Hapalindoles from the Cyanobacterium Hapalosiphon sp. Inhibit T Cell Proliferation

et al. 2019

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Supporting information available online at http://www.thieme-connect.de/products ABSTR AC T Novel immunomodulating agents are currently sought after for the treatment of autoimmune diseases and cancers. In this context, a screening campaign of a collection of 575 cyanobacteria extracts for immunomodulatory effects has been conducted. The screening resulted in several active extracts.Here we report the results of subsequent studies on an extract from the cyanobacterium Hapalosiphon sp. CBT1235. We identified 5 hapalindoles as the compounds responsible for the observed immunomodulatory effect. These indole alkaloids are produced by several strains of the cyanobacterial family Hapalosiphonaceae. They are known for their anti-infective, cytotoxic, and other bioactivities. Modulation of the activity of human immune cells has not yet been described. The immunomodulatory activity of the hapalindoles was characterized in vitro using flow cytometry-based measurements of T cell proliferation after carboxyfluorescein diacetate succinimidyl ester staining, and apoptosis and necrosis induction after annexin V/propidium iodide staining. The most potent compound, hapalindole A, reduced T cell proliferation with an IC 50 of 1.56 µM, while relevant levels of apoptosis were measurable only at 10-fold higher concentrations. Hapalindole A-formamide and hapalindole J-formamide, isolated for the first time from a natural source, had much lower activity than the nonformylated derivatives while, at the same time, being less selective for antiproliferative over apoptotic effects.

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“…Mehrere Mitglieder der Hapalindol‐Familie weisen sekundäre Chloride mit benachbarten quartären Stereozentren auf; das Motiv ist auch in mehreren Welwitindolinon‐Alkaloiden vorzufinden (siehe 93 , Schema , und 251 , Schema ). Johnston und Mitarbeiter synthetisierten die Hapalindole K ( 368 ) und A ( 6 ) über eine Diels‐Alder‐Cycloaddition von zwei hochsubstituierten Reaktionspartnern, dem trisubstituierten Dien 365 und dem β‐Chlor‐α‐methylenon 366 (Schema ) . Mit der passenden Lewis‐Säure verlief diese anspruchsvolle Cycloaddition in guter Ausbeute zum endo ‐Produkt (bezogen auf die Ketofunktion).…”

Section: Methoden Der Stereoselektiven Halogenierung Und Anwendungenunclassified

Stereoselektive Halogenierungen in der Naturstoffsynthese

Chung¹,

Vanderwal

2016

Angewandte Chemie

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Nach letzter Zählung sind nahezu 5000 halogenierte Naturstoffe entdeckt worden. In etwa der Hälfte dieser Verbindungen ist das Kohlenstoffatom, an welches das Halogen gebunden ist, sp3‐hybridisiert; es gibt also eine enorme Zahl von Naturstoffen, für welche die stereokontrollierte Halogenierung ein entscheidender Bestandteil der Synthesestrategie sein muss. In diesem Aufsatz diskutieren wir Methoden und Strategien, die zur stereoselektiven Einführung von Halogenatomen im Zusammenhang mit Naturstoffsynthesen genutzt wurden. Außerdem identifizieren wir verbliebene Lücken in der Synthesetechnologie sowie existierende Methoden, die noch nicht in der Synthese komplexer Moleküle verwendet wurden. Die hier beschriebene Chemie demonstriert erneut, wie Naturstoffe als Inspirationsquelle für wichtige Fortschritte in der chemischen Synthese dienen.

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Total Synthesis of the Chlorine‐Containing Hapalindoles K, A, and G

Cited by 41 publications

References 32 publications

Enantiospecific Total Syntheses of (+)‐Hapalindole H and (−)‐12‐epi‐Hapalindole U

Enantiospecific Total Syntheses of (+)‐Hapalindole H and (−)‐12‐epi‐Hapalindole U

Hapalindoles from the Cyanobacterium Hapalosiphon sp. Inhibit T Cell Proliferation

Stereoselektive Halogenierungen in der Naturstoffsynthese

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