Synthesis and Stereochemical Revision of the C31–C67 Fragment of Amphidinol 3

Wakamiya, Yuma; Ebine, Makoto; Murayama, Mariko; Omizu, Hiroyuki; Matsumori, Nobuaki; Murata, Michio; Oishi, Tohru

doi:10.1002/ange.201712167

Cited by 5 publications

(12 citation statements)

References 48 publications

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“…Interestingly, the central section C-30→C-49, including the two tetrahydropyran rings, was identical to the central core of AM3. Recently, Wakamiya et al [ 22 ] revised the absolute configuration of AM3 by comparing the NMR data between the natural product and the synthetic model compounds 4a and 4b . To establish the relative configuration of the common substructure in compound 1 , a comparative analysis of the NMR chemical shifts in 2:1 CD 3 OD/C 5 D 5 N ( Table S2 ) with those of 4a and 4b was carried out and the results are shown in Figure 4 .…”

Section: Resultsmentioning

confidence: 99%

Isolation and Structural Elucidation of New Amphidinol Analogues from Amphidinium carterae Cultivated in a Pilot-Scale Photobioreactor

et al. 2021

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The demand for valuable products from dinoflagellate biotechnology has increased remarkably in recent years due to their many prospective applications. However, there remain many challenges that need to be addressed in order to make dinoflagellate bioactives a commercial reality. In this article, we describe the technical feasibility of producing and recovering amphidinol analogues (AMs) excreted into a culture broth of Amphidinium carterae ACRN03, successfully cultured in an LED-illuminated pilot-scale (80 L) bubble column photobioreactor operated in fed-batch mode with a pulse feeding strategy. We report on the isolation of new structurally related AMs, amphidinol 24 (1, AM24), amphidinol 25 (2, AM25) and amphidinol 26 (3, AM26), from a singular fraction resulting from the downstream processing. Their planar structures were elucidated by extensive NMR and HRMS analysis, whereas the relative configuration of the C-32®C-47 bis-tetrahydropyran core was confirmed to be antipodal in accord with the recently revised configuration of AM3. The hemolytic activities of the new metabolites and other related derivatives were evaluated, and structure–activity conclusions were established. Their isolation was based on a straightforward and high-performance bioprocess that could be suitable for the commercial development of AMs or other high-value compounds from shear sensitive dinoflagellates.

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Section: Resultsmentioning

confidence: 99%

Isolation and Structural Elucidation of New Amphidinol Analogues from Amphidinium carterae Cultivated in a Pilot-Scale Photobioreactor

et al. 2021

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“…Two examples of synthetic studies of karlotoxin 2 (KmTx2) were reported by Hamann group (the C42À C63 section) [17] and Mohapatra group (the C29À C41 section). [18] We envisaged that the target compounds (1 a and 1 b) would be synthesized through the assembly of three components via alkenyllitiumaldehyde coupling of the B-ring aldehydes (2 a and 2 b) [13] and alkenyllithiums derived from the A-ring iodoolefins (3 a and 3 b), followed by Julia-Kocienski olefination with sulfone 4 [17] (Figure 1).…”

Section: Resultsmentioning

confidence: 99%

“…Having synthesized the A-ring fragments, we moved on to the coupling reactions (Scheme 2). The iodoolefin 3 a was treated with t-BuLi to generate alkenyllithium 15 a, which was coupled with the aldehyde 2 a [13] (1.1 equivalents to 3 a) to afford secondary alcohols 16 a (52% based on 3 a) and 17 a (14%) as a mixture of diastereomers at C41 in a 3.7 : 1 ratio. [22,23] Protection of the alcohol 16 a as TBS ether (81%) and removal of the PMB group of 18 a furnished primary alcohol 19 a (85%).…”

Section: Scheme 1 Synthesis Of the A-ring Iodoolefins (3 A And 3 B)mentioning

confidence: 99%

“…Having synthesized the diastereomers corresponding to the C30À C63 section of KmTx2, the 1 H and 13 C NMR data of 1 a and 1 b were compared with those of the natural product. The difference in the chemical shifts (Δδ) for the C30À C63 portion of KmTx2 and those of 1 a and 1 b are shown in Figure 4, (a) 1 H NMR and (b) 13 C NMR. The x-and y-axes represent proton or carbon number and Δδ in ppm, respectively.…”

Section: Comparison Of Nmr Data Of 1 a And 1 B With Those Of Kmtx2mentioning

confidence: 99%

“…[11] During course of the synthetic studies of AM3, [12,13] we have revised the absolute configuration around the A-ring system at C32À C36 and C38, revealing that the A-and B-rings are antipodal ( Figure 1). [13] Although the absolute configuration at C39 of AM3 was determined to be R by modified Mosher method [14] of the degradation product, determination of the relative configuration between C38 and C39 was difficult based on the J-based configuration analysis (JBCA) method [15] because the observed coupling constants were medium values. Initially, the relative configuration between C38 and C39 was determined to be threo, but actually erythro, resulted in the misassignment of the absolute configuration at C32À C36 and C38.…”

Section: Introductionmentioning

confidence: 99%

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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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Determination of the Absolute Configuration of Super‐Carbon‐Chain Compounds by a Combined Chemical, Spectroscopic, and Computational Approach: Gibbosols A and B

Yan

et al. 2020

Angewandte Chemie

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Marine dinoflagellates produce remarkable organic molecules, particularly those with polyoxygenated long‐carbon‐chain backbones, namely super‐carbon‐chain compounds (SCCCs), characterized by the presence of numerous stereogenic carbon centers on acyclic polyol carbon chains. Even today, it is a challenge to determine the absolute configurations of these compounds. In this work, the planar structures and absolute configurations of two highly flexible SCCCs, featuring either a C69‐ or C71‐linear carbon backbone, gibbosols A and B, respectively, each containing thirty‐seven stereogenic carbon centers, were unambiguously established by a combined chemical, spectroscopic, and computational approach. The discovery of gibbosols A and B with two hydrophilic acyclic polyol chains represents an unprecedented class of SCCCs. A reasonable convergent strategy for the biosynthesis of these SCCCs was proposed.

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Synthesis and Stereochemical Revision of the C31–C67 Fragment of Amphidinol 3

Cited by 5 publications

References 48 publications

Isolation and Structural Elucidation of New Amphidinol Analogues from Amphidinium carterae Cultivated in a Pilot-Scale Photobioreactor

Isolation and Structural Elucidation of New Amphidinol Analogues from Amphidinium carterae Cultivated in a Pilot-Scale Photobioreactor

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

Determination of the Absolute Configuration of Super‐Carbon‐Chain Compounds by a Combined Chemical, Spectroscopic, and Computational Approach: Gibbosols A and B

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