A Chemoenzymatic Total Synthesis of the Undecenolide ( - )-Cladospolide C

A stereoselective total synthesis of an antiproliferative and antifungal natural product, (6 S)-5,6-dihydro-6-[(2 R)-2-hydroxy-6-phenylhexyl]-2 H-pyran-2-one has been accomplished using the Barbier allylation, LiAlH4/LiI mediated syn-stereoselective reduction and olefin ring-closing metathesis (RCM) as the key steps. L-Malic acid was used as a chiral precursor for the construction of syn-1,3-diol moiety of the molecule.

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Crystal structure of 5-[(benzoyloxy)methyl]-5,6-dihydroxy-4-oxocyclohex-2-en-1-yl benzoate

Acta Crystallographica Section E Crystallographic Communications ◽

10.1107/s2056989020007793 ◽

2020 ◽

Vol 76 (7) ◽

pp. 1096-1100

Author(s):

Theerachart Leepasert ◽

Patchreenart Saparpakorn ◽

Kittipong Chainok ◽

Tanwawan Duangthongyou

Keyword(s):

Crystal Structure ◽

Hydrogen Bonds ◽

Single Crystal ◽

Natural Product ◽

Dihedral Angle ◽

Absolute Configuration ◽

Hydroxyl Groups ◽

X Ray Diffraction ◽

X Ray ◽

Ring Form

The crystal structure of the natural product zeylenone, C21H18O7, was confirmed by single-crystal X-ray diffraction. The crystal structure has three chiral centers at positions C1, C5 and C6 of the cyclohexanone ring, but the absolute configuration could not be determined reliably. The methyl benzoate and benzoyloxy substituents at positions C1 and C5 of the cyclohexenone ring are on the same side of the ring with the dihedral angle between their mean planes being 16.25 (10)°. These rings are almost perpendicular to the cyclohexenone ring. The benzoate groups and two hydroxyl groups on the cyclohexenone ring form strong hydrogen bonds to consolidate the crystal structure. In addition, weak C—H...O hydrogen bonds also contribute to the packing of the structure.

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Synthesis of Carbocyclic Nucleosides (+)-Neplanocin A, (+)-Aristeromycin and 4'-epi-(+)-Aristeromycin from D-Fructose

Letters in Organic Chemistry ◽

10.2174/1570178615666181023145502 ◽

2019 ◽

Vol 16 (9) ◽

pp. 750-758

Author(s):

Perali R. Sridhar ◽

Vennam D.K. Reddy ◽

Mandava Suresh ◽

Nadiveedhi M. Reddy ◽

K. Shiva Kumar

Keyword(s):

Total Synthesis ◽

Allylic Alcohol ◽

Starting Material ◽

Carbocyclic Nucleosides ◽

Ring Closing Metathesis ◽

Neplanocin A ◽

Oxidative Rearrangement ◽

Key Steps

D-Fructose is used as the chiral pool starting material for the stereoselective total synthesis of (+)-neplanocin A. Zinc mediated fragmentation, ring-closing metathesis and oxidative rearrangement of cyclic tertiary allylic alcohol are used as the key steps in achieving the synthesis of key carbocylic intermediate. Further, stereoselective total synthesis of 4'-epi-(+)-aristeromycin and the conversion of (+)-neplanocin A to a mixture of (+)-aristeromycin and 4'-epi-(+)-aristeromycin are described.

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First Total Synthesis of Varioxiranol A

Molecules ◽

10.3390/molecules24050862 ◽

2019 ◽

Vol 24 (5) ◽

pp. 862 ◽

Cited By ~ 1

Author(s):

Angelika Lásiková ◽

Jana Doháňošová ◽

Mária Štiblariková ◽

Martin Parák ◽

Ján Moncol ◽

...

Keyword(s):

Total Synthesis ◽

Single Crystal ◽

Absolute Configuration ◽

Coupling Reaction ◽

X Ray ◽

Synthetic Strategy

The paper describes the first total synthesis of natural varioxiranol A by chiral pool approach and confirmation of its absolute configuration by single-crystal X-ray analysis. The target varioxiranol A and its 4-epimer were obtained after 10 steps from single and available chiral source 1,2-O-isopropylidene-d-glyceraldehyde in an overall yield of 10% and 6%, respectively. A synthetic strategy based on the Julia–Kocieński coupling reaction between aromatic sulfone and corresponding aldose derivative makes it possible to prepare other interesting polyketide derivatives (varioxiranols B-G, varioxirane, varioxiranediols).

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Pigments of Fungi. XLVIII Clavorubin from Two Australasian Toadstools of the Genus Cortinarius and the X-Ray Crystal Structure of the Methyl Ester of 6-O-Methylclavorubin

Australian Journal of Chemistry ◽

10.1071/c97185 ◽

1998 ◽

Vol 51 (5) ◽

pp. 347 ◽

Cited By ~ 1

Author(s):

Melvyn Gill ◽

Malcolm S. Buchanan ◽

Peter J. Steel ◽

Nives M. Milanovic ◽

Somphone Phonh-Axa

Keyword(s):

Crystal Structure ◽

Carboxylic Acid ◽

Methyl Ester ◽

Single Crystal ◽

Natural Product ◽

Structure Analysis ◽

Claviceps Purpurea ◽

Chemical Methods ◽

X Ray ◽

First Time

Clavorubin (1,5,6,8-tetrahydroxy-3-methyl-9,10-dioxoanthracene-2-carboxylic acid) (1), previously known only from the ascomycetious rye fungus Claviceps purpurea (‘ergot’), has been isolated from the fruit bodies of two Australasian basidiomycetes belonging to the genus Cortinarius and characterized by spectroscopic and chemical methods. A single-crystal X-ray structure analysis of the methyl ester (4) of 6-O-methylclavorubin establishes unequivocally, for the first time, the structure of the natural product.

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Cinerin C: a macrophyllin-type bicyclo[3.2.1]octane neolignan fromPleurothyrium cinereum(Lauraceae)

Acta Crystallographica Section C Crystal Structure Communications ◽

10.1107/s0108270112030946 ◽

2012 ◽

Vol 68 (8) ◽

pp. o320-o322

Author(s):

Ericsson D. Coy-Barrera ◽

Luis E. Cuca-Suárez ◽

Michael Sefkow ◽

Uwe Schilde

Keyword(s):

Hydrogen Bond ◽

Circular Dichroism ◽

Single Crystal ◽

Absolute Configuration ◽

Ethanol Extract ◽

X Ray ◽

Naturally Occurring ◽

First Time ◽

Circular Dichroïsm

The structure of naturally-occurring cinerin C [systematic name: (7S,8R,3′R,4′S,5′R)-Δ8′-4′-hydroxy-5,5′,3′-trimethoxy-3,4-methylenedioxy-2′,3′,4′,5′-tetrahydro-2′-oxo-7.3′,8.5′-neolignan], isolated from the ethanol extract of leaves ofPleurothyrium cinereum(Lauraceae), has previously been established by NMR and HRMS spectroscopy, and its absolute configuration established by circular dichroism measurements. For the first time, its crystal strucure has now been established by single-crystal X-ray analysis, as the monohydrate, C22H26O7·H2O. The bicyclooctane moiety comprises fused cyclopentane and cyclohexenone rings which are almost coplanar. An intermolecular O—H...O hydrogen bond links the 4′-OH and 5′-OCH3groups along thecaxis.

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5α,8α-Epidioxysterols from a Formosan Sponge, Axinyssa sp

Natural Product Communications ◽

10.1177/1934578x1300801108 ◽

2013 ◽

Vol 8 (11) ◽

pp. 1934578X1300801

Author(s):

Tzu-Rong Su ◽

Kai-Ju Liang ◽

Michael Y. Chiang ◽

Mei-Chin Lu ◽

Yu-Jen Wu ◽

...

Keyword(s):

Single Crystal ◽

Diffraction Analysis ◽

Cell Lines ◽

Cancer Cell ◽

Absolute Configuration ◽

Cancer Cell Lines ◽

Spectroscopic Methods ◽

X Ray Diffraction ◽

X Ray ◽

First Time

One new 5α,8α-epidioxysterol, 3-acetylaxinysterol (1), along with one known sterol, axinysterol (2), were isolated from a Formosan sponge, Axinyssa sp.. The structures of the compounds were determined by spectroscopic methods and the absolute configuration of 2 was further confirmed by single-crystal X-ray diffraction analysis for the first time. Compound 2 exhibited significant cytotoxicity against K562 and Molt 4 cancer cell lines.

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Concise Diastereoselective Total Synthesis of (±)-Parvistemonine A

Synlett ◽

10.1055/s-0040-1707283 ◽

2020 ◽

Vol 31 (18) ◽

pp. 1800-1804

Author(s):

Kazuyuki Sugita ◽

Rintaro Matsuo ◽

Ayumu Miyashita ◽

Motoi Kuwabara ◽

Shinya Adachi ◽

...

Keyword(s):

Total Synthesis ◽

Michael Addition ◽

Wittig Reaction ◽

Crystallographic Analysis ◽

Mitsunobu Reaction ◽

X Ray ◽

Linear Sequence ◽

Relative Stereochemistry ◽

Key Steps ◽

First Time

AbstractWe have developed a concise diastereoselective total synthesis of (±)-parvistemonine A. By using a Mukaiyama–Michael addition, an aza-Wittig reaction, a Paal–Knorr pyrrole synthesis, an acid-mediated annulation, and a Mitsunobu reaction as key steps, we achieved a total synthesis in which the longest linear sequence was ten steps and the overall yield was 19.6%. Additionally, the relative stereochemistry of parvistemonine A was confirmed by X-ray crystallographic analysis for the first time.

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Multimodule Assembly Strategy for Diverted Total Synthesis and Stereochemical Determination of Laingolide A and Laingolide

10.26434/chemrxiv.14347145 ◽

2021 ◽

Author(s):

Chengsen Cui ◽

Yecai Lai ◽

Wei-Min Dai

Keyword(s):

Total Synthesis ◽

Absolute Configuration ◽

Ring Closing Metathesis ◽

Assembly Strategy ◽

Planar Structures ◽

Relative Stereochemistry ◽

Stereogenic Centers ◽

Target Molecules ◽

First Time

Diverted total synthesis of diastereomers of laingolide A and laingolide has been accomplished and the stereochemistry of both (E)-enamide-containing 15-membered macrolides has been assigned. Laingolide A and laingolide have 3 and 4 stereogenic centers, respectively, and only their planar structures were reported. The former has 4 possible diastereomers while the latter has up to 8 diastereomers. A multimodule assembly (MMA) strategy was utilized to disconnect both target molecules into 5 small structural modules among which only one stereochemically varied module (stereo-module) needed to be prepared with other 4 modules available commercially. A sequence of ring-closing metathesis (RCM) and alkene isomerization was used for construction of the macrocyclic skeleton and installation of the (E)-enamide moiety. Four each diastereomers of laingolide A and laingolide have been synthesized, leading to assignment of (2R*,7R*,9S*) and (2R*,4R*,7R*,9S*) relative stereochemistry for laingolide A and laingolide, respectively. Moreover, according to the (2S,9R) absolute configuration of the congener, laingolide B, the (2S,7S,9R) and (2S,4S,7S,9R) absolute configurations are suggested for laingolide A and laingolide, respectively. The current synthetic efforts reveal, for the first time, that both laingolide A and laingolide possess the 7,9-syn-Me/t-Bu subunit.

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Multimodule Assembly Strategy for Diverted Total Synthesis and Stereochemical Determination of Laingolide A and Laingolide

10.26434/chemrxiv.14347145.v1 ◽

2021 ◽

Author(s):

Chengsen Cui ◽

Yecai Lai ◽

Wei-Min Dai

Keyword(s):

Total Synthesis ◽

Absolute Configuration ◽

Ring Closing Metathesis ◽

Assembly Strategy ◽

Planar Structures ◽

Relative Stereochemistry ◽

Stereogenic Centers ◽

Target Molecules ◽

First Time

Diverted total synthesis of diastereomers of laingolide A and laingolide has been accomplished and the stereochemistry of both (E)-enamide-containing 15-membered macrolides has been assigned. Laingolide A and laingolide have 3 and 4 stereogenic centers, respectively, and only their planar structures were reported. The former has 4 possible diastereomers while the latter has up to 8 diastereomers. A multimodule assembly (MMA) strategy was utilized to disconnect both target molecules into 5 small structural modules among which only one stereochemically varied module (stereo-module) needed to be prepared with other 4 modules available commercially. A sequence of ring-closing metathesis (RCM) and alkene isomerization was used for construction of the macrocyclic skeleton and installation of the (E)-enamide moiety. Four each diastereomers of laingolide A and laingolide have been synthesized, leading to assignment of (2R*,7R*,9S*) and (2R*,4R*,7R*,9S*) relative stereochemistry for laingolide A and laingolide, respectively. Moreover, according to the (2S,9R) absolute configuration of the congener, laingolide B, the (2S,7S,9R) and (2S,4S,7S,9R) absolute configurations are suggested for laingolide A and laingolide, respectively. The current synthetic efforts reveal, for the first time, that both laingolide A and laingolide possess the 7,9-syn-Me/t-Bu subunit.

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