A Stereoselective Route to Guanacastepene A through a Surprising Epoxidation This work was supported by the National Institutes of Health (CA-28824). S.L. is a US Army breast cancer research program postdoctoral fellow (DAMD-17-99-1-9373). G.B.D. is an NIH postdoctoral fellow (1 F32 NS11150-01). D.S.T. is a Damon Runyon Cancer Research Foundation postdoctoral fellow (DRG-1641). We thank Dr. George Sukenick and Sylvi Rusli (NMR Core Facility, CA-02848) for mass spectral analyses.

Lin, Songnian; Dudley, Gregory B.; Tan, Derek S.

doi:10.1002/1521-3757(20020617)114:12<2292::aid-ange2292>3.0.co;2-a

Cited by 10 publications

(2 citation statements)

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“…Seemingly, a clear route to 1 was in place. However, as described in the following paper, some major surprises awaited us in completing this goal 27…”

Section: Methodsmentioning

confidence: 99%

Synthesis of the Functionalized Tricyclic Skeleton of Guanacastepene A: A Tandem Epoxide-Opening β-Elimination/Knoevenagel Cyclization This work was supported by the National Institutes of Health (HL-25848 and CA-28824). D.S.T. is a Damon Runyon Cancer Research Foundation postdoctoral fellow (DRG-1641). G.B.D. is an NIH postdoctoral fellow (1 F32 NS11150-01). We thank Dr. George Sukenick and Sylvi Rusli (NMR Core Facility, CA-02848) for mass spectral analyses.

Tan

Dudley

2002

Angew. Chem.

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Der Ring ist geschlossen! Die ernsthaften Probleme, die der Ringschluss zur Kerneinheit von Guanacastepen A 1 aufwarf – insbesondere die der unterschiedlichen Oxidationszustände von C14 und C15 –, ließen sich erfolgreich lösen (siehe Schema). Obwohl noch nicht verallgemeinert, sollte die vorgestellte Methode für breitere Anwendungen beim Aufbau inkrementell oxygenierter polycyclischer Naturstoffe geeignet sein.

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“…Seemingly, a clear route to 1 was in place. However, as described in the following paper, some major surprises awaited us in completing this goal 27…”

Section: Methodsmentioning

confidence: 99%

Synthesis of the Functionalized Tricyclic Skeleton of Guanacastepene A: A Tandem Epoxide-Opening β-Elimination/Knoevenagel Cyclization This work was supported by the National Institutes of Health (HL-25848 and CA-28824). D.S.T. is a Damon Runyon Cancer Research Foundation postdoctoral fellow (DRG-1641). G.B.D. is an NIH postdoctoral fellow (1 F32 NS11150-01). We thank Dr. George Sukenick and Sylvi Rusli (NMR Core Facility, CA-02848) for mass spectral analyses.

Tan

Dudley

2002

Angew. Chem.

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“…Pioneering work in this field has been carried out by Danishefsky, who disclosed the total synthesis of guanacastepene A ( 1 ) in 2002 7a,b. The effective strategy for assembly of the tricyclic carbon core involved functionalization of an A‐ring building block followed by alkylation and cyclization to construct the A–B hydroazulene (Scheme , strategy I).…”

Section: Introductionmentioning

confidence: 99%

Cyclohexyne Cycloinsertion in the Divergent Synthesis of Guanacastepenes

Gampe

Carreira

2012

Chemistry A European J

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The guanacastepenes are a family of 15 diterpenes that share a common 5-6-7 tricyclic core, which is decorated with quaternary centers, unsaturation, hydroxyl and carbonyl groups. Some of these natural products show interesting antimicrobial potency. Their collective structural and biological features have stirred up vibrant activity among organic chemists. Herein, we disclose an account of our studies toward the synthesis of a number of guanacastepenes. The synthetic strategy relies on the use of cyclohexyne in a cycloinsertion reaction to rapidly construct the guanacastepene core. Isolation of a cyclobutenol as intermediate in the cyclohexyne cycloinsertion provided us with the possibility to study further the reactivity of this metastable compound, and we uncovered novel rearrangements and ring-opening reactions. Stereoselective, late-stage oxidative diversification of the carbon scaffold allowed the synthesis of guanacastepenes N and O and paved the way for the synthesis of guanacastepenes H and D.

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Metathesereaktionen in der Totalsynthese

2005

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Mit Ausnahme der palladiumkatalysierten Kreuzkupplungsreaktionen hatte im vergangenen Vierteljahrhundert keine Reaktionsklasse einen derart weitreichenden Einfluss auf die Kohlenstoff‐Kohlenstoff‐Verknüpfung und die Totalsynthese wie die Metathesereaktionen von Olefinen, Eninen, und Alkinen. In diesem Aufsatz präsentieren wir Glanzlichter aus einer Reihe ausgewählter Totalsynthesen, in denen diese eleganten und effizienten Reaktionen entscheidend zum Erfolg beigetragen haben. Schon an ihrer kurzen, aber beeindruckenden Geschichte kann man ablesen, dass die Bedeutung dieser Reaktionen für die chemische Synthese weiter zunehmen wird.

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Abstract: Ein externes Oxidationsmittel nähert sich syn den Isopropyl‐ und Methylsubstituenten des fünfgliedrigen Rings von 1. Die daraus hervorgehende überraschende und selektive Epoxidierung wurde erfolgreich für die Totalsynthese des Antibiotikums Guanacastepen A 2 genutzt.

Cited by 10 publications

References 7 publications

Cyclohexyne Cycloinsertion in the Divergent Synthesis of Guanacastepenes

Metathesereaktionen in der Totalsynthese

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