Monanchorin, a Bicyclic Alkaloid from the Sponge Monanchora ungiculata

Meragelman, Karina M.; McKee, Tawnya C.; McMahon, James B.

doi:10.1021/np030434i

Cited by 37 publications

(37 citation statements)

References 18 publications

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“…This group consists of bicyclic [7][8], tricyclic [9][10][11][12][13][14][15][16][17], pentacyclic [8,10,12,[16][17][18][19][20][21][22][23][24] and acyclic [25,26] natural products found in different species of the genus. The alkaloids demonstrate a broad spectrum of biological activities [1][2][3][4][5][6][7][8][11][12][13][14][15][16][17][18][19][20][22][23][24][25][26], including potent cytotoxic effects, induction of cellular apoptosis, and inhibition of the TRPV1 receptor [25,26].…”

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confidence: 99%

Monanchomycalin C, a New Pentacyclic Guanidine Alkaloid from the Far-Eastern Marine Sponge Monanchora Pulchra

Tabakmakher

Денисенко

Guzii

et al. 2013

Natural Product Communications

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A new pentacyclic guanidine alkaloid, monanchomycalin C (1), along with the earlier known ptilomycalin A (2), were isolated from the Far-Eastern marine sponge Monanchora pulchra. The structure of 1 was elucidated using 1D and 2D NMR spectroscopic and mass spectrometric data. Compounds 1 and 2 exhibited cytotoxic activities against human breast cancer MDA-MB-231 cells with IC 50 values of 8.2 µM and 4.3 µM, respectively.

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confidence: 99%

Monanchomycalin C, a New Pentacyclic Guanidine Alkaloid from the Far-Eastern Marine Sponge Monanchora Pulchra

Tabakmakher

Денисенко

Guzii

et al. 2013

Natural Product Communications

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“…1 The carbon skeleton was assigned on the basis of 2D NMR experiments, leading to two possible aminal structures 1 and 2 that differ in the connection of the guanidine to the carbon chain. The 13 C NMR shifts fit better with calculated values for 1 suggesting that this is the correct structure.…”

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Synthesis of (+)- and (−)-Monanchorin

Snider

2009

Org. Lett.

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The optically pure epoxy acetal was converted to the protected guanidino alcohol by reaction with NaN 3 in DMF, hydrogenation of the azide, and reaction of the amine with MeSC(NBoc)NHBoc, AgNO 3 and Et 3 N. Treatment of the protected guanidino alcohol with 9:1 CDCl 3 /TFA afforded monanchorin, whose absolute stereochemistry was assigned as shown.McKee and coworkers recently isolated the weakly cytotoxic monanchorin (1) from the sponge Monanchora ungiculata collected in the Maldive islands (see Scheme 1). 1 The carbon skeleton was assigned on the basis of 2D NMR experiments, leading to two possible aminal structures 1 and 2 that differ in the connection of the guanidine to the carbon chain. The 13 C NMR shifts fit better with calculated values for 1 suggesting that this is the correct structure. This is consistent with the known reaction of trans-2-hydroxycyclohexylguanidine with cyclohexanone to afford aminal 3, whose structure has been established crystallographically. 2 Crambesidin acid was also isolated from this sponge and other polycyclic crambescidin, ptilocaulin, and batzelladine guanidine alkaloids have been isolated from Monanchora sponges. As part of our continuing interest in the synthesis of these guanidine alkaloids, 3 we decided to investigate the synthesis of monanchorin.Monanchorin is the aminal formed from the intramolecular dehydration of erythro-4-guanidino-5-hydroxydecanal. Initially we decided to investigate the reaction of guanidine with epoxy aldehyde 4 hoping that the guanidine would add initially to the aldehyde and then to the proximal end of the epoxide to form a hemi-aminal with regiochemical control. 4 Unfortunately, treatment of 4 5 with guanidine resulted in decomposition. We then turned to the nonregioselective preparation of guanidino hydroxy acetal 5 from epoxy acetal 6.Protection of 4E-decenal (7) with HC(OMe) 3 and camphorsulfonic acid (CSA) in MeOH afforded the acetal quantitatively, which was treated with Shi's D-fructose derived ketone (8)

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“…163 There is a significant synthetic interest in these guanidinium natural products due to the fact that these cationic natural compounds can mimic cellular ions and inhibit ion pumps (e.g., Na + /K + -ATPase or Ca 2+ -ATPase). 164 O'Doherty and co-workers devised an asymmetric approach, 165 to access both Monanchorin enantiomers.…”

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confidence: 99%

Achmatowicz reaction and its application in the syntheses of bioactive molecules

Ghosh

Brindisi

2016

RSC Adv.

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Substituted pyranones and tetrahydropyrans are structural subunits of many bioactive natural products. Considerable efforts are devoted toward the chemical synthesis of these natural products due to their therapeutic potential as well as low natural abundance. These embedded pyranones and tetrahydropyran structural motifs have been the subject of synthetic interest over the years. While there are methods available for the syntheses of these subunits, there are issues related to regio and stereochemical outcomes, as well as versatility and compatibility of reaction conditions and functional group tolerance. The Achmatowicz reaction, an oxidative ring enlargement of furyl alcohol, was developed in the 1970s. The reaction provides a unique entry to a variety of pyranone derivatives from functionalized furanyl alcohols. These pyranones provide convenient access to substituted tetrahydropyran derivatives. This review outlines general approaches to the synthesis of tetrahydropyrans, covering general mechanistic aspects of the Achmatowicz reaction or rearrangement with an overview of the reagents utilized for the Achmatowicz reaction. The review then focuses on the synthesis of functionalized tetrahydropyrans and pyranones and their applications in the synthesis of natural products and medicinal agents.

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Monanchorin, a Bicyclic Alkaloid from the Sponge Monanchora ungiculata

Abstract: Monanchorin, a guanidine alkaloid with an unusual bicyclic skeleton, together with the known pentacyclic alkaloid crambescidin acid have been isolated from the aqueous extract of the sponge Monanchoraungiculata.

Cited by 37 publications

References 18 publications

Monanchomycalin C, a New Pentacyclic Guanidine Alkaloid from the Far-Eastern Marine Sponge Monanchora Pulchra

Monanchomycalin C, a New Pentacyclic Guanidine Alkaloid from the Far-Eastern Marine Sponge Monanchora Pulchra

Synthesis of (+)- and (−)-Monanchorin

Achmatowicz reaction and its application in the syntheses of bioactive molecules

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