Enantioselective Total Synthesis of the Diterpene (+)‐Cubitene

Simon, Kristina; Wefer, Johannes; Schöttner, Elisabeth; Lindel, Thomas

doi:10.1002/anie.201205143

Cited by 15 publications

(10 citation statements)

References 32 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Cleavage of the p-methoxyphenyl ether in 4 with ceric(IV) ammonium nitrate followed by oxidation of the primary alcohol 22 with Dess-Martin periodinane afforded (+)-11-deoxynorleucosceptroid A (23), which has not yet been isolated from natural sources. [29] Regioselective ahydroxylation (LHMDS, O 2 , P(OEt) 3 ) [30] of 22 afforded two C11 hydroxylated products, which were directly oxidized under mild conditions (IBX, DMSO) [31] without prior purification. NMR analysis of the resulting product mixture revealed that a-hydroxylation had occurred with high stereoselectivity.…”

Section: Methodsmentioning

confidence: 99%

A General Entry to Antifeedant Sesterterpenoids: Total Synthesis of (+)‐Norleucosceptroid A, (−)‐Norleucosceptroid B, and (−)‐Leucosceptroid K

Hugelshofer

Magauer

2014

Angew Chem Int Ed

View full text Add to dashboard Cite

The first asymmetric total synthesis of the antifeedant terpenoids (+)-norleucosceptroid A, (-)-norleucosceptroid B, and (-)-leucosceptroid K has been accomplished. This highly concise synthetic route was guided by our efforts to develop a platform for the collective synthesis of a whole family of antifeedant natural products. The synthesis features a Hauser-Kraus-type annulation followed by an unprecedented, highly efficient intramolecular dilactol aldol-type condensation reaction to produce the 5,6,5 skeleton. The developed synthetic route proceeds for norleucosceptroid A and B in 16 steps (longest linear sequence) from known compounds.

show abstract

Section: Methodsmentioning

confidence: 99%

A General Entry to Antifeedant Sesterterpenoids: Total Synthesis of (+)‐Norleucosceptroid A, (−)‐Norleucosceptroid B, and (−)‐Leucosceptroid K

Hugelshofer

Magauer

2014

Angew Chem Int Ed

View full text Add to dashboard Cite

show abstract

“…[36] Hence, af ew steps should convert mono-o rd ifluorinated compounds TC3-TC7 or TC13 into specificallyf luorinated strychnine analogs.…”

Section: Discussionmentioning

confidence: 99%

“…Four additional steps are necessary to complete the total synthesis of brucine, a strychnine relative not prepared by total synthesis so far.O verall, the resultsu nderscore the efficacy and the flexibility of samarium diiodide-promoted cyclization reactions to interesting scaffolds suitable for naturalproduct synthesis. [36]…”

Section: Discussionmentioning

confidence: 99%

Stereoselective Cascade Cyclizations with Samarium Diiodide to Tetracyclic Indolines: Precursors of Fluorostrychnines and Brucine

Beemelmanns

Nitsch

Bentz

et al. 2019

Chemistry A European J

View full text Add to dashboard Cite

As eries of g-indolylketones with fluorine, cyano or alkoxy substituents at the benzene moiety was prepared and subjected to samarium diiodide-promoted cyclization reactions. The desired dearomatizing ketyl cascade reaction formingt wo new rings proceeded in all cases with high diastereoselectivity,b ut with differing product distribution. In most cases, the desired annulated tetracyclic compounds were obtained in moderate to good yields, but as second product tetracyclic spirolactones were isolated in up to 29 % yield. The reaction rate was influencedb yt he substituents at the benzenem oiety of the substrate as expected, with electron-accepting groups acceleratingand electron-donating groups deceleratingt he cyclizationp rocess. In case of a difluoro-substituted g-indolylketone ap artial defluorination was observed.T he intermediate samarium enolateo ft he tetracyclic products could be trappedb ya dding reactive alkylating agents as electrophiles delivering products with quarternaryc arbons. In the case of ad imethoxy-substituted tetracyclic cyclization product as ubsequentr eductivea minations tereoselectively provided ap entacyclic compound that was subsequently N-protected and subjected to aregioselectivee limination.T he obtained functionalized pentacyclic product should be convertible into the alkaloid brucine by four well-established steps. Overall,t he presented report showst hat functionalized tetracyclic compounds with different substituents are rapidly availablew ith the samarium diiodidec ascade cyclization as crucial step. Hence, analogueso ft he landmarka lkaloid strychnine, fore xample, with specific fluorine substitutions, should be easily accessible.Scheme1.Samarium diiodide-promoted cyclizationso fN -acylatedindole derivatives A stereoselectively leadingt ot ricyclic compounds B and proposed transitions tate TS1.Supporting information and the ORCID identification number(s) for the author(s) of this articlecan be found under: https://doi. Scheme5.Cascadec yclizations of fluoro-substituted indole derivatives SM3-SM7 leading to tetracyclic compounds TC3-TC7 and spirolactones SL3-SL7 and cyclizations of cyano-and alkoxy-substitutedi ndolederivatives SM8-SM12 to TC8-TC12 and SL8-SL12.

show abstract

“…This route is scalable, as evident from the fact that more than 1.2 g of 2 could be obtained. Furthermore, regioselective a-hydroxylation (LDA, then O 2 and P(OEt) 3 ) [7,17] of 2 delivered leucosceptroid A in 60 % yield.…”

Section: Methodsmentioning

confidence: 99%

Total Synthesis of Leucosceptroids A and B

Guo

Liu

2014

Angew Chem Int Ed

View full text Add to dashboard Cite

Leucosceptroids A and B are sesterterpenoids with potent antifeedant and antifungal activities. A more efficient gram-scale total synthesis of leucosceptroid B and the first total synthesis of leucosceptroid A are presented. The key transformations include an aldol reaction between a substituted dihydrofuranone and an (S)-citronellal-derived aldehyde, a SmI2-mediated intramolecular ketyl-olefin radical cyclization, and final-stage alcohol oxidation.

show abstract

Enantioselective Total Synthesis of the Diterpene (+)‐Cubitene

Cited by 15 publications

References 32 publications

A General Entry to Antifeedant Sesterterpenoids: Total Synthesis of (+)‐Norleucosceptroid A, (−)‐Norleucosceptroid B, and (−)‐Leucosceptroid K

A General Entry to Antifeedant Sesterterpenoids: Total Synthesis of (+)‐Norleucosceptroid A, (−)‐Norleucosceptroid B, and (−)‐Leucosceptroid K

Stereoselective Cascade Cyclizations with Samarium Diiodide to Tetracyclic Indolines: Precursors of Fluorostrychnines and Brucine

Total Synthesis of Leucosceptroids A and B

Contact Info

Product

Resources

About