The marine sponge Agelas citrina as a source of the new pyrrole–imidazole alkaloids citrinamines A–D and N-methylagelongine

• Christine Cychon,
• Ellen Lichte and
• Matthias Köck

Beilstein J. Org. Chem. 2015, 11, 2029–2037, doi:10.3762/bjoc.11.220

• Christine Cychon Ellen Lichte Matthias Kock Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung, Am Handelshafen 12, 27570 Bremerhaven, Germany 10.3762/bjoc.11.220 Abstract The chemical investigation of the Caribbean sponge Agelas citrina revealed four new pyrrole–imidazole

• alkaloids (PIAs), the citrinamines A–D (1–4) and the bromopyrrole alkaloid N-methylagelongine (5). All citrinamines are dimers of hymenidin (6) which was also isolated from this sponge as the major metabolite. Citrinamines A (1) and B (2) are derivatives of the PIA dimer mauritiamine (7), whereas

• [1]. The chemical investigation of the Caribbean sponge Agelas citrina yielded the following known monomeric PIAs: hymenidin (6) [2], keramadine (13) [3], dispacamide B (14) [4], mukanadin B (15) [5], 2-debromotaurodispacamide A (16) [6], tauroacidin B (17) [7], and the dimeric PIA benzosceptrin B

Total synthesis of panicein A₂

• Lili Yeung,
• Lisa I. Pilkington,
• Melissa M. Cadelis,
• Brent R. Copp and
• David Barker

Beilstein J. Org. Chem. 2015, 11, 1991–1996, doi:10.3762/bjoc.11.215

• panicein A (1), Figure 1), hydroquinone moiety (as seen in paniceins D (2), F (3) and F1 (4)) or chromenol as seen in panicein A2 (5). The first members of the panicein family were isolated by Cimino et al. in 1973 from the marine sponge Halichondria panacea [1]; members of this family have since been

Preparation of conjugated dienoates with Bestmann ylide: Towards the synthesis of zampanolide and dactylolide using a facile linchpin approach

• Jingjing Wang,
• Samuel Z. Y. Ting and
• Joanne E. Harvey

Beilstein J. Org. Chem. 2015, 11, 1815–1822, doi:10.3762/bjoc.11.197

• structurally related marine natural products, zampanolide (2) and dactylolide (3, Figure 1), wherein the Bestmann ylide represents a C1–C2 linchpin that connects two segments of the macrocylic ring. (−)-Zampanolide (2, Figure 1) was first isolated from the marine sponge Fasciospongia rimosa found at Cape Zampa

• , Japan [21], and subsequently from a Tongan sponge Cacospongia mycofijiensis [22]. It was found to exhibit potent anticancer activities, with IC50 values in the nM scale against a number of cell lines [22][23]. The structurally related compound, (+)-dactylolide, was discovered in the marine sponge

Pyridinoacridine alkaloids of marine origin: NMR and MS spectral data, synthesis, biosynthesis and biological activity

• Louis P. Sandjo,
• Victor Kuete and
• Maique W. Biavatti

Beilstein J. Org. Chem. 2015, 11, 1667–1699, doi:10.3762/bjoc.11.183

• different substituents (arnoamines A–D, Figure 14) does not significantly change the activity and they seem less active than their congeners, cystodytins (70–76) [84]. Kuanoniamine A (60), an alkaloid obtained from the marine sponge Oceanapia sagittaria, was found to be a potent growth inhibitor of tumor

• alkaloids such as meridine (56) that are found to exert its antifungal activity via the inhibition of nucleic acid biosynthesis [87]. Petrosamine B (99), isolated from the sponge Oceanapia sp., inhibited the Helicobacter pylori enzyme aspartyl semialdehyde dehydrogenase explaining it as an antibacterial

Exploring monovalent and multivalent peptides for the inhibition of FBP21-tWW

• Lisa Maria Henning,
• Sumati Bhatia,
• Miriam Bertazzon,
• Michaela Marczynke,
• Oliver Seitz,
• Rudolf Volkmer,
• Rainer Haag and
• Christian Freund

Beilstein J. Org. Chem. 2015, 11, 701–706, doi:10.3762/bjoc.11.80

• ], and polyamidoamine [11] are taken up by the cell and localize to endosomes or endolysosomes, where they lead to proton pumping and concomitant influx due to a proton sponge effect [12], increasing the ionic strength in these organelles. Eventually, this leads to osmotic rupture of the endosome and

Anomalous diffusion of Ibuprofen in cyclodextrin nanosponge hydrogels: an HRMAS NMR study

• Monica Ferro,
• Franca Castiglione,
• Carlo Punta,
• Lucio Melone,
• Walter Panzeri,
• Barbara Rossi,
• Francesco Trotta and
• Andrea Mele

Beilstein J. Org. Chem. 2014, 10, 2715–2723, doi:10.3762/bjoc.10.286

• structure of the CDNSEDTA 1:8 is expected to show a high degree of heterogeneity in the distribution of pores, due to rearrangements caused by the steric hindrance. The TEM image of Figure 4b shows the details of the pores heterogeneity and the sponge-like morphology. The slightly superdiffusive behaviour

Formal total syntheses of classic natural product target molecules via palladium-catalyzed enantioselective alkylation

• Yiyang Liu,
• Marc Liniger,
• Ryan M. McFadden,
• Jenny L. Roizen,
• Jacquie Malette,
• Corey M. Reeves,
• Douglas C. Behenna,
• Masaki Seto,
• Jimin Kim,
• Justin T. Mohr,
• Scott C. Virgil and
• Brian M. Stoltz

Beilstein J. Org. Chem. 2014, 10, 2501–2512, doi:10.3762/bjoc.10.261

• [43], completing the formal synthesis of (−)-quinic acid (21). Additionally, one could in principle also access the less commercially abundant antipode (+)-quinic acid (21) using the catalyst (R)-t-Bu-PHOX. C) Dysidiolide Dysidiolide (29, Scheme 6) was isolated from the marine sponge Dysidea etheria

Total synthesis of the proposed structure of astakolactin

• Takayuki Tonoi,
• Keisuke Mameda,
• Moe Fujishiro,
• Yutaka Yoshinaga and
• Isamu Shiina

Beilstein J. Org. Chem. 2014, 10, 2421–2427, doi:10.3762/bjoc.10.252

• sesterterpene metabolite isolated from the marine sponge Cacospongia scalaris, has been achieved, mainly featuring Johnson–Claisen rearrangement, asymmetric Mukaiyama aldol reaction and MNBA-mediated lactonization. Keywords: aldol reaction; astakolactin; lactonization; MNBA; terpenoids; Introduction

• Astakolactin (1) is a novel sesterterpene metabolite [1][2][3][4][5] first reported in 2003 by Roussis et al [6]. It was isolated from the marine sponge Cacospongia scalaris, which was collected from the gulf of Astakos in the Ionian Sea near Greece. The structure proposed for compound 1 is a bicyclic linear

Concise total synthesis of two marine natural nucleosides: trachycladines A and B

• Haixin Ding,
• Wei Li,
• Zhizhong Ruan,
• Ruchun Yang,
• Zhijie Mao,
• Qiang Xiao and
• Jun Wu

Beilstein J. Org. Chem. 2014, 10, 1681–1685, doi:10.3762/bjoc.10.176

• ]. The initial discovery of marine nucleosides can be traced back to the identifications of spongothymidine and spongouridine in the early 1950s from the Caribbean sponge Tethyacrypta [8][9], which subsqeuently led to the commercialization of arabinofuranosylcytosine (Ara-C) [10], arabinofuranosyladenine

• biological activity of trachycladine B has not been reported yet due to its insufficient availability in natural resources. Trachycladines A, which was isolated from the same sponge natural product Trachycladus laevispirulifer (and also from the sponges Theonella cupola and Theonella sp) in 1995 [13][14

Rational design of cyclopropane-based chiral PHOX ligands for intermolecular asymmetric Heck reaction

• Marina Rubina,
• William M. Sherrill,
• Alexey Yu. Barkov and
• Michael Rubin

Beilstein J. Org. Chem. 2014, 10, 1536–1548, doi:10.3762/bjoc.10.158

• employment of proton sponge as a base resulted in significant isomerization of product 3a into the more thermodynamically stable dihydrofurans 4a and 20a. Close monitoring of the reaction by chiral GC revealed, that the initially formation of “normal” product 3a is observed (Table 1, entry 4); however, by

• presence of Hünig’s base (Table 3, entries 2 and 5). Employment of proton sponge helped boost the reaction rate in the arylation catalyzed by both L4 and L5 (Table 3, entries 3 and 6). Yet, significant isomerization of 3 into 4 was observed with this base when the reaction catalyzed by Pd/L4 complex was

• a result, the selectivity toward formation of 3 was slightly lower in these cases. Reactions performed in the presence of Pd/L5 catalyst and proton sponge proceeded much faster, albeit providing somewhat lower ee's (Table 4, entries 6–10). In contrast to the Pd/L4-catalyzed reactions

New sesquiterpene hydroquinones from the Caribbean sponge Aka coralliphagum

• Qun Göthel and
• Matthias Köck

Beilstein J. Org. Chem. 2014, 10, 613–621, doi:10.3762/bjoc.10.52

• a sample of the Caribbean sponge Aka coralliphagum collected off the coast of San Salvador in the Bahamas. The structures of the new compounds were elucidated on the basis of mass spectrometric and NMR spectroscopic analysis. Compounds 1–4 are derivatives of siphonodictyal E (9). Siphonodictyal E4

• ; natural products; NMR; sesquiterpene hydroquinone; structure elucidation; Introduction Aka coralliphagum (Siphonodictyon coralliphagum) is known to have four distinct morphological forms: forma typica, f. tubulosa, f. obruta, and f. incrustans [1]. This sponge has the ability to burrow into live coral

• heads, leaving only the oscular chimney protruding (typica) or the flat crusts (incrustans) exposed. The oscular chimneys or the flat crusts are encircled by a so-called "dead zone" which protects the sponge from overgrowth [2]. Sullivan and Faulkner have proposed that the coral polyps are killed by the

An oxidative amidation and heterocyclization approach for the synthesis of β-carbolines and dihydroeudistomin Y

• Suresh Babu Meruva,
• Akula Raghunadh,
• Raghavendra Rao Kamaraju,
• U. K. Syam Kumar and
• P. K. Dubey

Beilstein J. Org. Chem. 2014, 10, 471–480, doi:10.3762/bjoc.10.45

• activity. Xestomanzamine A (3) [5] is a β-carboline alkaloid with an 1-methyl-1H-imidazole-5-acyl group at the C-1 position and was isolated from the Okinawan marine sponge Xestopongia sp. The other β-carboline alkaloids reported in the literature are fascaplysin (4) [7], eudistomin A (5a) [3], harmine (5b

Total synthesis and cytotoxicity of the marine natural product malevamide D and a photoreactive analog

• Werner Telle,
• Gerhard Kelter,
• Heinz-Herbert Fiebig,
• Peter G. Jones and
• Thomas Lindel

Beilstein J. Org. Chem. 2014, 10, 316–322, doi:10.3762/bjoc.10.29

• -BuOAc (Scheme 1). β-Hydroxyhexanoate 6 was obtained as a mixture of diastereomers (5:4), which was separated by column chromatography (silica) on a multigram scale. Treatment of (3R,4S)-6 with Meerwein's salt in presence of proton sponge afforded Cbz-protected MMMAH tert-butyl ester 7 in 87% yield

Synthesis of five- and six-membered cyclic organic peroxides: Key transformations into peroxide ring-retaining products

• Alexander O. Terent'ev,
• Dmitry A. Borisov,
• Vera A. Vil’ and
• Valery M. Dembitsky

Beilstein J. Org. Chem. 2014, 10, 34–114, doi:10.3762/bjoc.10.6

Plakilactones G and H from a marine sponge. Stereochemical determination of highly flexible systems by quantitative NMR-derived interproton distances combined with quantum mechanical calculations of ¹³C chemical shifts

• Simone Di Micco,
• Angela Zampella,
• Maria Valeria D’Auria,
• Carmen Festa,
• Simona De Marino,
• Raffaele Riccio,
• Craig P. Butts and
• Giuseppe Bifulco

Beilstein J. Org. Chem. 2013, 9, 2940–2949, doi:10.3762/bjoc.9.331

• sponge Plakinastrella mamillaris collected at Fiji Islands, is reported. The stereostructural studies began on plakilactone H by applying an integrated approach of the NOE-based protocol and quantum mechanical calculations of 13C chemical shifts. In particular, plakilactone H was used as a template to

• conformationally flexible oxygenated polyketides, plakilactone G (1) and H (2) (Figure 1), isolated from a Fiji collection of the marine sponge Plakinastrella mamillaris. Results and Discussion Isolation and determination of the constitution of plakilactones G and H The chloroform extract from the Kupchan

• chemical shift data and supported by the NOE-distance data, we suggest that the structure of plakilactone G is as depicted in 1a and the absolute configuration of plakilactone H as depicted in 2b. Conclusion In this paper two new plakilactones are reported from the marine sponge Plakinastrella mamillaris

Synthesis and determination of the absolute configuration of (−)-(5R,6Z)-dendrolasin-5-acetate from the nudibranch Hypselodoris jacksoni

• I. Wayan Mudianta,
• Victoria L. Challinor,
• Anne E. Winters,
• Karen L. Cheney,
• James J. De Voss and
• Mary J. Garson

Beilstein J. Org. Chem. 2013, 9, 2925–2933, doi:10.3762/bjoc.9.329

• lochi [22], from three Hypselodoris spp. [18], and from the marine sponge Dictyodendrilla sp. [23]. The current study reports the isolation and synthesis of (−)-(5R,6Z)-dendrolasin-5-acetate (1), with the determination of the absolute configuration at C-5 by spectroscopic analysis of the

Stereodivergent synthesis of jaspine B and its isomers using a carbohydrate-derived alkoxyallene as C₃-building block

• Volker M. Schmiedel,
• Stefano Stefani and
• Hans-Ulrich Reissig

Beilstein J. Org. Chem. 2013, 9, 2564–2569, doi:10.3762/bjoc.9.291

• . Keywords: chiral auxiliaries; gold catalysis; jaspine B; lithiated alkoxyallenes; natural product synthesis; pachastrissamine; tetrahydrofurans; Introduction Jaspine B, also known as pachastrissamine (1, Scheme 1), is an anhydrophytosphingosine derivative, isolated 2002 from the marine sponge Pachastrissa

• sp. by Higa et al. [1]. In 2003 Debitus et al. were able to extract this natural product from the marine sponge Jaspis sp. [2]. Jaspine B (1) comprises a densely functionalized tetrahydrofuran ring, bearing three contiguous (2S,3S,4S)-configured stereogenic centers with a long alkyl chain at C-2 and

The chemistry of isoindole natural products

• Klaus Speck and
• Thomas Magauer

Beilstein J. Org. Chem. 2013, 9, 2048–2078, doi:10.3762/bjoc.9.243

• (PDE4) inhibitor apremilast (11), which lacks the glutarimide is currently in phase III clinical trials. The first naturally occurring isoindole, 6-methoxy-2,5-dimethyl-2H-isoindole-4,7-dione (18), was isolated from the sponge Reniera sp. in 1982 [10]. The postulated structure was elucidated through

• with ammonia in aqueous ammonium chloride solution (pH 8). Muironolide A (204) was isolated by Molinski from the marine sponge Phorbas sp. in 2009 [150]. The molecular framework of this unique natural product has a hexahydro-1H-isoindolinone-triketide, a trans-2-chlorocyclopropane and a

• trichlorocarbinol ester. A first biological evaluation showed that 204 displays antifungal activity. However, only 90 µg could be isolated and further biological screening was not possible [151]. Several sponge-derived macrolides have proven to be effective cytotoxic agents [152][153] and one could speculate that

New tridecapeptides of the theonellapeptolide family from the Indonesian sponge Theonella swinhoei

• Annamaria Sinisi,
• Barbara Calcinai,
• Carlo Cerrano,
• Henny A. Dien,
• Angela Zampella,
• Claudio D’Amore,
• Barbara Renga,
• Stefano Fiorucci and
• Orazio Taglialatela-Scafati

Beilstein J. Org. Chem. 2013, 9, 1643–1651, doi:10.3762/bjoc.9.188

• Marine Park of Manado (North Sualwesi, Indonesia) in January 2010 and frozen immediately after collection. A reference sample of the sponge has been deposited at the Department of Pharmacy, University of Naples Federico II, with the code Man-10-06. The frozen material (16.5 g) was extracted with methanol

A³-Coupling catalyzed by robust Au nanoparticles covalently bonded to HS-functionalized cellulose nanocrystalline films

• Jian-Lin Huang,
• Derek G. Gray and
• Chao-Jun Li

Beilstein J. Org. Chem. 2013, 9, 1388–1396, doi:10.3762/bjoc.9.155

• coupled plasma (ICP) analytical techniques. Both the HS-CNC and the Au sponge were inactive, implying that the Au is the active site and that the controlling of Au nanoparticle size is essential for the present reactions. The catalytic activity first increased with the increase of the Au loading up to 4.4

Simple and rapid hydrogenation of p-nitrophenol with aqueous formic acid in catalytic flow reactors

• Rahat Javaid,
• Shin-ichiro Kawasaki,
• Akira Suzuki and
• Toshishige M. Suzuki

Beilstein J. Org. Chem. 2013, 9, 1156–1163, doi:10.3762/bjoc.9.129

• precipitation. Selective dissolution of the less-noble element out of a bimetallic mixture or alloy results in the formation of a unique metallic sponge structure of the noble component [34][35]. We attempted to modify the reactor wall with a porous Pd layer. Continuous passage of 4 M HNO3 into the reactor with

Thioester derivatives of the natural product psammaplin A as potent histone deacetylase inhibitors

• Matthias G. J. Baud,
• Thomas Leiser,
• Vanessa Petrucci,
• Mekala Gunaratnam,
• Stephen Neidle,
• Franz-Josef Meyer-Almes and
• Matthew J. Fuchter

Beilstein J. Org. Chem. 2013, 9, 81–88, doi:10.3762/bjoc.9.11

• represents the first example of a disulfide and oxime containing metabolite isolated from a marine sponge. Since its initial report by Crews and co-workers as a potent HDAC inhibitor [16], psammaplin A has provided inspiration for the development of new HDAC inhibitors with novel structures [19]. Recently

A new approach toward the total synthesis of (+)-batzellaside B

• Jolanta Wierzejska,
• Shin-ichi Motogoe,
• Yuto Makino,
• Tetsuya Sengoku,
• Masaki Takahashi and
• Hidemi Yoda

Beilstein J. Org. Chem. 2012, 8, 1831–1838, doi:10.3762/bjoc.8.210

• a sponge Batzella sp. collected off the west coast of Madagascar, represent the first example of iminosugars from a marine organism [11]. These naturally occurring products have been demonstrated to retain a remarkably high degree of potency against Staphylococcus epidermidis with MICs of ≤6.3 μg/mL

Marilones A–C, phthalides from the sponge-derived fungus Stachylidium sp.

• Celso Almeida,
• Stefan Kehraus,
• Miguel Prudêncio and
• Gabriele M. König

Beilstein J. Org. Chem. 2011, 7, 1636–1642, doi:10.3762/bjoc.7.192

• 10.3762/bjoc.7.192 Abstract The marine-derived fungus Stachylidium sp. was isolated from the sponge Callyspongia sp. cf. C. flammea. Culture on a biomalt medium supplemented with sea salt led to the isolation of three new phthalide derivatives, i.e., marilones A–C (1–3), and the known compound silvaticol

• cm. Fungal material. The marine-derived fungus Stachylidium sp. was isolated from the sponge Callyspongia sp. cf. C. flammea (collected at Bear Island, Sydney, Australia) and identified by P. Massart and C. Decock, BCCM/MUCL, Catholic University of Louvain, Belgium. A specimen is deposited at the

Application of the diastereoselective photodeconjugation of α,β-unsaturated esters to the synthesis of gymnastatin H

• Ludovic Raffier and
• Olivier Piva

Beilstein J. Org. Chem. 2011, 7, 151–155, doi:10.3762/bjoc.7.21

• , gymnastatins 10 constitute a family of compounds isolated from Gymnascella dankaliensis which grows in symbiosis with the marine sponge Halichondria japonica [10] (Figure 2). Gymnastatins 10 possess a common unsaturated fatty acid residue connected to a tyrosine subunit. These compounds have been reported to