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

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

• halenaquinol sulfate from the marine sponge Xestospongia sapra [14]. In the course of our investigation on the sponge Aka coralliphagum, we isolated a number of compounds containing sulfated phenols. These sulfated metabolites are labile [5], and easily loose the sulfate ester groups by hydrolysis in water [15

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

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

• 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

• ”, via D. Montesano 49, 80131 Napoli, Italy Department of Chemistry, University of Bristol, Cantocks Close, BS8 1TS Bristol, United Kingdom 10.3762/bjoc.9.331 Abstract In this paper the stereostructural investigation of two new oxygenated polyketides, plakilactones G and H, isolated from the marine

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

• 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

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

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

Carbasugar analogues of galactofuranosides: α-O-linked derivatives

• Jens Frigell and
• Ian Cumpstey

Beilstein J. Org. Chem. 2010, 6, 1127–1131, doi:10.3762/bjoc.6.129

• oligosaccharides, including plant polysaccharides [5], fungal cell wall polysaccharides [6], glycolipids from thermophilic bacteria [7] and glycosphingolipids from marine sponge (agelagalastatin) [8]. Moreover, the precursor to β-galactofuranosides and the substrate for galactofuranosyltransferases is UDP