Diastereoselective synthesis of the C29–C41 fragment of karlotoxin 2

Reddy, D. Narasimha; Gaddam, Janardhan; Devunuri, Nagaraju; Mohapatra, Debendra K.

doi:10.1016/j.tetlet.2015.05.051

Cited by 10 publications

(2 citation statements)

References 20 publications

(7 reference statements)

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“…Removal of the TBS group using HF-Py (70% v/v) in THF afforded the alcohol 24 in 82% yield . The allyl alcohol 24 was oxidized to the corresponding ketone 9 with Dess–Martin periodinane in CH 2 Cl 2 with 89% yield. RCM reaction of a 0.001 M solution of the bis-olefin 9 with 10 mol % of Hovyeda Grubbs’ second-generation catalyst heating under reflux conditions for 3 h in anhydrous, degassed CH 2 Cl 2 provided the required 14-membered- E -lactone 7 as the sole product in 80% yield (Scheme ).…”

Section: Resultssupporting

confidence: 54%

Total Synthesis and Structural Revision of Greensporone F and Dechlorogreensporone F

et al. 2020

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The first asymmetric total syntheses of the real isolation product (2S,5R,8R)-greensporone F and (2S,5R,8R)-dechlorogreensporone F, 14-membered resorcylic acid lactones with a cis-2,5-disubstituted tetrahydrofuran ring system, was accomplished. The synthesis features a late-stage Lewis acid-catalyzed stereoselective intramolecular oxa-Michael reaction, E-selective ring-closing metathesis, De Brabander’s esterification, and Jacobsen’s hydrolytic kinetic resolution as the key steps. Synthesis of both real isolation and erroneously proposed structure necessitated the revision of the absolute configuration of greensporone F and dechlorogreensporone F. The erroneous representation of (2S,5S,8S)-configuration in greensporone F and dechlorogreensporone F was assigned to be (2S,5R,8R) by comparison with the NMR data and specific rotation of the synthetic compounds with that of the reported data.

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Section: Resultssupporting

confidence: 54%

Total Synthesis and Structural Revision of Greensporone F and Dechlorogreensporone F

et al. 2020

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“…Synthesis of the C30−C63 section of karlotoxin 2 . Two examples of synthetic studies of karlotoxin 2 (KmTx2) were reported by Hamann group (the C42−C63 section) and Mohapatra group (the C29−C41 section) . We envisaged that the target compounds ( 1 a and 1 b ) would be synthesized through the assembly of three components via alkenyllitium‐aldehyde coupling of the B‐ring aldehydes ( 2 a and 2 b ) and alkenyllithiums derived from the A‐ring iodoolefins ( 3 a and 3 b ), followed by Julia‐Kocienski olefination with sulfone 4 (Figure ).…”

Section: Resultsmentioning

confidence: 99%

Synthesis and Stereochemistry of the C30−C63 Section of Karlotoxin 2

Umeno

Oishi

2020

Asian J Org Chem

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Karlotoxin 2 (KmTx2) is a marine natural product isolated from the dinoflagellate Karlodinium veneficum. The absolute configuration of KmTx2 was determined by NMR analysis in combination with degradation of the natural product, and the absolute configuration at C49 was revised by computational analysis. On the other hand, we reported revision of the absolute configuration of amphidinol 3 (AM3), whose structure is similar to that of KmTx2, by comparing NMR data of the synthesized partial structures and total synthesis of AM3. In this paper, we report the synthesis of the partial structures of KmTx2 corresponding to the C30À C63 section, and the diastereomer at C37, C41À C43, and C45À C49, which is hypothetically proposed on the basis of the revised structure of AM3. Comparison of the NMR data of the synthetic specimens with those of the natural product suggested that the absolute configuration of KmTx2 is revised to be 37R, 41R, 42R, 43R, 45R, 46R, 47R, 48S, and 49S.

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General Asymmetric Synthetic Strategy for the α‐Alkylated 2,5,6‐Trisubstituted Pyran of Indanomycin and Related Natural Products

et al. 2020

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A general synthetic strategy for convergent asymmetric synthesis of C1–C10 fragment of tetraene‐containing natural product indanomycin was achieved starting from 2‐(benzyloxy)acetaldehyde which in turn was obtained from very inexpensive material cis‐1,4‐butene‐diol. Key steps include Evans' aldol reaction, HWE olefination, iodine‐catalyzed tandem isomerization followed by C–O and C–C bond formation similar to our earlier report in constructing the trans‐2,6‐disubstituted dihydropyran ring and Evans' asymmetric alkylation.

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Diastereoselective synthesis of the C29–C41 fragment of karlotoxin 2

Cited by 10 publications

References 20 publications

Total Synthesis and Structural Revision of Greensporone F and Dechlorogreensporone F

Total Synthesis and Structural Revision of Greensporone F and Dechlorogreensporone F

Synthesis and Stereochemistry of the C30−C63 Section of Karlotoxin 2

General Asymmetric Synthetic Strategy for the α‐Alkylated 2,5,6‐Trisubstituted Pyran of Indanomycin and Related Natural Products

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