Bromotyrosine-derived alkaloids from the Caribbean sponge Aplysina lacunosa

• Qun Göthel,
• Thanchanok Sirirak and
• Matthias Köck

Beilstein J. Org. Chem. 2015, 11, 2334–2342, doi:10.3762/bjoc.11.254

• . Bromotyrosine alkaloid (21) isolated from the sponge Verongula sp. NMR data (600 MHz, DMSO-d6) of 14-debromo-11-deoxyfistularin-3 (1) and 11-deoxyfistularin-3 (8). 13C NMR data (600 MHz, DMSO-d6) of the central benzene ring of the isolated compounds 1 and 4. NMR data (600 MHz, DMSO-d6) of aplysinin A (2

Beyond catalyst deactivation: cross-metathesis involving olefins containing N-heteroaromatics

• Kevin Lafaye,
• Cyril Bosset,
• Lionel Nicolas,
• Amandine Guérinot and
• Janine Cossy

Beilstein J. Org. Chem. 2015, 11, 2223–2241, doi:10.3762/bjoc.11.241

• temperature (Scheme 11) [48]. This method was used to prepare polycyclic scaffolds that can be encountered in diverse alkaloid natural products such as coralyne and berberine (Scheme 12) [49]. Similarly, enyne ring-closing metathesis reactions were performed to access a variety of vinyl-3,4

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

• 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

• (10) [8][9][10] (Figure 1). Additionally, five new compounds, four with a dimeric PIA structure (1–4) and the N-methyl analogue (5) of the bromopyrrole alkaloid agelongine (12) [11], were isolated. Herein, we describe the isolation and structure elucidation of citrinamines A (1), B (2), and N

• the marine sponge Agelas citrina revealed four new compounds of the pyrrole–imidazole alkaloid (PIA) family. Citrinamines A (1) and B (2) are closely related to mauritiamine (7) which can be seen as the most less complex dimeric PIA (the first published one) in which the monomeric units are only

Asymmetric 1,4-bis(ethynyl)bicyclo[2.2.2]octane rotators via monocarbinol functionalization. Ready access to polyrotors

• Cyprien Lemouchi and
• Patrick Batail

Beilstein J. Org. Chem. 2015, 11, 1881–1885, doi:10.3762/bjoc.11.202

• obtainment of 14 (Scheme 4), a new class of extended alkaloid ligands similar to isonicotinic acid (of much smaller spatial extension) which was obtained recently in a synthesis of a simple Li(I) salt with an extended framework by Abrahams, Robson and co-workers [21]. Compound 13 was prepared either from 5

• potential in the development of molecular machines that can perform mechanical functions can now be systematically studied. Synthesis of the asymmetric rotor 1. Synthesis of dirotors 6 and 10. Synthesis of the tertiary amide 12. Synthesis of the extended alkaloid ligand 14. Supporting Information

Recent applications of ring-rearrangement metathesis in organic synthesis

• Sambasivarao Kotha,
• Milind Meshram,
• Priti Khedkar,
• Shaibal Banerjee and
• Deepak Deodhar

Beilstein J. Org. Chem. 2015, 11, 1833–1864, doi:10.3762/bjoc.11.199

• (Scheme 6). The erythrina alkaloids are known to exhibit sedative, hypotensive and neuromuscular activity. This alkaloid skeleton consists of a tetracyclic spiroamine framework and synthetic chemists consider it as a challenging target. Simpkins and co-workers [11] have used the RRM sequence tactically to

• spiropiperidine alkaloid nitramine was proved to be efficient by this methodology (Scheme 13). In 2004, Ni and Ma [18] have described the synthesis of bicyclic compounds 75 and 76 by adopting a metathesis protocol with catalysts 1 and 2 in good yields, but the product ratio is catalyst-dependent. In this context

• derivative 104 were obtained in a 22:78 ratio (Scheme 21). Aubé and co-workers [26] have accomplished the asymmetric synthesis of the dendrobatid alkaloid 251F by employing a RRM as the key step. The required building block 108a has been synthesized from enone 107 via a RRM protocol. When enone 107 was

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

• , dihydroacridine, and quinolone cores are features regularly found in these alkaloid skeletons. The lack of hydrogen atoms next to quaternary carbon atoms for two or three rings makes the chemical shift assignment a difficult task. In this regard, one of the aims of this review is the compilation of previously

• comprised of four to eight fused rings including heterocycles [34][35][36][37][38][39]. Acridine, acridone, dihydroacridine, and quinolone cores [33][40] are features regularly found in these alkaloid skeletons. The high conjugation of their structure induces a strong electron delocalization, leading to

• conditions. The bipyridine derivative obtained was subjected to a strong base (sodium hydride) to give 12-deoxyascididemin which was immediately oxidized in situ by oxygen to yield ascididemin (42, Scheme 6) [65]. Synthesis of subarine (37) Method A: This alkaloid was successfully prepared in five steps with

Fates of imine intermediates in radical cyclizations of N-sulfonylindoles and ene-sulfonamides

• Hanmo Zhang,
• E. Ben Hay,
• Stephen J. Geib and
• Dennis P. Curran

Beilstein J. Org. Chem. 2015, 11, 1649–1655, doi:10.3762/bjoc.11.181

• alkaloid aspidophytine published in 2008 [14]. In 2005, Stevens and coworkers reported that treatment of trichloroacetamide-substituted N-sulfonylindole 3 under conditions for copper-catalyzed atom transfer cyclization provided chlorine transfer product 4 with the N-sulfonyl group intact (Scheme 1) [15

Dicarboxylic esters: Useful tools for the biocatalyzed synthesis of hybrid compounds and polymers

• Ivan Bassanini,
• Karl Hult and
• Sergio Riva

Beilstein J. Org. Chem. 2015, 11, 1583–1595, doi:10.3762/bjoc.11.174

• 18, obtained by linking together a steroid (cortisone, 14) and an alkaloid (colchicoside, 15; thiocolchicoside, 16). Worth of notice the use, among others, of activated esters of dithio-dicarboxylic acids, in 18. More recently Kren and coworkers have synthesized hybrid dimeric antioxidants 23–25

Pd(OAc)₂-catalyzed dehydrogenative C–H activation: An expedient synthesis of uracil-annulated β-carbolinones

• Biplab Mondal,
• Somjit Hazra,
• Tarun K. Panda and
• Brindaban Roy

Beilstein J. Org. Chem. 2015, 11, 1360–1366, doi:10.3762/bjoc.11.146

• ]. For example, SL651498 was documented as a potential drug development candidate in a research program designed to discover subtype-selective GABAA receptor agonists for the treatment of muscle spasms and generalized anxiety disorder [13]. β-Carbolinones such as strychnocarpine, the alkaloid from

Selected synthetic strategies to cyclophanes

• Sambasivarao Kotha,
• Mukesh E. Shirbhate and
• Gopalkrushna T. Waghule

Beilstein J. Org. Chem. 2015, 11, 1274–1331, doi:10.3762/bjoc.11.142

A new and convenient synthetic way to 2-substituted thieno[2,3-b]indoles

• Roman A. Irgashev,
• Arseny A. Karmatsky,
• Gennady L. Rusinov and
• Valery N. Charushin

Beilstein J. Org. Chem. 2015, 11, 1000–1007, doi:10.3762/bjoc.11.112

• attention of researchers, mainly due to the fact that thieno[2,3-b]indole derivatives exhibit a wide range of biological properties, and can be regarded as promising compounds for agricultural or pharmacological applications. For example, the alkaloid thienodolin [1], isolated from the fermentation mixture

Gold-catalyzed formation of pyrrolo- and indolo-oxazin-1-one derivatives: The key structure of some marine natural products

• Sultan Taskaya,
• Nurettin Menges and
• Metin Balci

Beilstein J. Org. Chem. 2015, 11, 897–905, doi:10.3762/bjoc.11.101

• , such as lukianol A (1) and lukianol B (2) (Figure 1) [8][9][10]. Lukianol B (2) was found to be the most potent human aldose reductase (h-ALR2) inhibitor in thousands of marine natural products screened [11]. The ningalin B alkaloid 3, having an isomeric pyrrolo-oxazinone skeleton, possesses antitumor

Novel stereocontrolled syntheses of tashiromine and epitashiromine

• Loránd Kiss,
• Enikő Forró and
• Ferenc Fülöp

Beilstein J. Org. Chem. 2015, 11, 596–603, doi:10.3762/bjoc.11.66

• . Tashiromine is a natural indolizidine alkaloid isolated from Maackia tashiroi (1990). Strategies for the synthesis of indolizidine derivatives have received considerable interest from synthetic and medicinal chemists (Figure 2). A number of synthetic approaches have been described earlier for construction of

• concentrated under reduced pressure. The crude oil was purified by column chromatography on silica gel (CH2Cl2/MeOH/NH4OH 90:8:2 or CH2Cl2/MeOH/NH4OH 90:5:5) to give the alkaloid. Ethyl (1R*,2S*)-2-(benzyloxycarbonylamino)cyclooct-5-enecarboxylate ((±)-3) A colourless oil (Rf 0.6, n-hexane/EtOAc 4:1); yield

Diastereoselective and enantioselective conjugate addition reactions utilizing α,β-unsaturated amides and lactams

• Katherine M. Byrd

Beilstein J. Org. Chem. 2015, 11, 530–562, doi:10.3762/bjoc.11.60

Chemoselective O-acylation of hydroxyamino acids and amino alcohols under acidic reaction conditions: History, scope and applications

• Tor E. Kristensen

Beilstein J. Org. Chem. 2015, 11, 446–468, doi:10.3762/bjoc.11.51

• , Trost and Genêt used a careful O-acetylation of an amino alcohol alkaloid intermediate with acetic anhydride in CH2Cl2 acidified with HClO4 as part of a total synthesis (Scheme 15) [88]. In the footsteps of Bretschneider, chemoselective O-acetylation of natural product amino alcohols also inspired

Stereoselective cathodic synthesis of 8-substituted (1R,3R,4S)-menthylamines

• Carolin Edinger,
• Jörn Kulisch and
• Siegfried R. Waldvogel

Beilstein J. Org. Chem. 2015, 11, 294–301, doi:10.3762/bjoc.11.34

• tools in organic synthesis. Among numerous applications they are applied as chiral ligands [1], as catalysts for various asymmetric transformations [2], and as building blocks for alkaloid and pharmaceutical drug synthesis [3][4]. The increasing number of applications leads to a growing interest in the

Formation of nanoparticles by cooperative inclusion between (S)-camptothecin-modified dextrans and β-cyclodextrin polymers

• Thorbjørn Terndrup Nielsen,
• Catherine Amiel,
• Laurent Duroux,
• Kim Lambertsen Larsen,
• Lars Wagner Städe,
• Reinhard Wimmer and
• Véronique Wintgens

Beilstein J. Org. Chem. 2015, 11, 147–154, doi:10.3762/bjoc.11.14

• specific delivery of drugs to the desired place of action lowers the adverse effects associated with conventional chemotherapy tremendously [3]. Therefore, much effort is continuously being made to develop novel drug-carrier systems. (S)-Camptothecin (CPT) is a natural cytotoxic quinoline alkaloid with a

The Shono-type electroorganic oxidation of unfunctionalised amides. Carbon–carbon bond formation via electrogenerated N-acyliminium ions

• Alan M. Jones and
• Craig E. Banks

Beilstein J. Org. Chem. 2014, 10, 3056–3072, doi:10.3762/bjoc.10.323

• afforded the carbonyl compound and the 5,6 and 6,6-ring systems of the target compounds. Toyooka and co-workers have designed a route to both enantiomers of the quinolizidine poison frog alkaloid 195C. Key to the success of their synthetic endeavour was the preparation via direct anodic oxidation of

• glycine cation equivalents. Steckhan and co-workers have previously demonstrated the power of electrosynthetic chiral glycine equivalents [99][100]. Combination of technology and natural product analogue synthesis Lastly, Ley and co-workers have recently reported the expedient synthesis of indole alkaloid

• oxidation used in the preparation of the poison frog alkaloid 195C [80]. Preparation of iminosugars using an electrochemical approach [81]. The electrosynthetic preparation of α-L-fucosidase inhibitors [84][85]. Enantioselective synthesis of the anaesthetic ropivacaine 85 [71]. The preparation of

Come-back of phenanthridine and phenanthridinium derivatives in the 21st century

• Lidija-Marija Tumir,
• Marijana Radić Stojković and
• Ivo Piantanida

Beilstein J. Org. Chem. 2014, 10, 2930–2954, doi:10.3762/bjoc.10.312

• potential carcinogenic and mutagenic properties of some derivatives (EB and analogues), which had negative influence on biomedically-oriented studies of the complete phenanthridine class till the end of the 20th century. However, discovery of phenanthridine alkaloid analogues and in parallel new studies of

• bioactivity-guided fractionation, the bioactive compound chelerythrine (21, a quaternary benzo[c]phenanthridine alkaloid) was isolated from Chelidonium majus L. [103]. In addition to strong antihelmintic activity (against D. intermedius), chelerythrine also showed antimicrobial, antifungal and anti

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

• synthetic approaches have been reported [61][62]. One popular target in this family is aspidospermine (36, Scheme 8). Although its medicinal potency is inferior to other members of the class, this alkaloid has served as a proving ground for many synthetic chemists. In 1989, Meyers reported an

• enantioselective synthesis of the (4aS,8aR,8S)-hydrolilolidone core 37 [63][64] present in aspidospermine (36), and thus a formal total synthesis of the alkaloid itself, intercepting Stork’s classic route [61]. One precursor described in the core synthesis is enone 38, which bears the quaternary stereocenter of

• [71]. It features a tetracyclic scaffold with a nine-membered ring and an all-carbon quaternary stereocenter. This alkaloid is a microtubule-disrupting agent that displays similar cellular effects to paclitaxel [72][73]. Because of its biological activities and potential pharmaceutical use, many

Chiral phosphines in nucleophilic organocatalysis

• Yumei Xiao,
• Zhanhu Sun,
• Hongchao Guo and
• Ohyun Kwon

Beilstein J. Org. Chem. 2014, 10, 2089–2121, doi:10.3762/bjoc.10.218

• , Kwon and Andrews completed the first enantioselective total synthesis of the indole alkaloid (+)-ibophyllidine in 15 steps and 13% overall yield from N-Boc-indole-3-aldehyde (Scheme 32) [66]. This approach was the first non-formal total synthesis of a complex natural product employing phosphine

Selective allylic hydroxylation of acyclic terpenoids by CYP154E1 from Thermobifida fusca YX

• Anna M. Bogazkaya,
• Clemens J. von Bühler,
• Sebastian Kriening,
• Alexandrine Busch,
• Alexander Seifert,
• Jürgen Pleiss,
• Sabine Laschat and
• Vlada B. Urlacher

Beilstein J. Org. Chem. 2014, 10, 1347–1353, doi:10.3762/bjoc.10.137

• Catharanthus roseus [40] has been cloned and heterologously expressed in baculovirus-infected insect cells [41]. This cytochrome P450 monooxygenase belonging to the CYP76B family has been demonstrated to be involved into the biosynthesis of the alkaloid secologanin, and produced 8-hydroxynerol. It should be

Preparation of phosphines through C–P bond formation

• Iris Wauters,
• Wouter Debrouwer and
• Christian V. Stevens

Beilstein J. Org. Chem. 2014, 10, 1064–1096, doi:10.3762/bjoc.10.106

• used to carry out an asymmetric alkylation reaction (Scheme 4). The monoalkylation of phosphine–borane complex 15 was performed in the presence of the Cinchona alkaloid ammonium salt 16 [50]. However, the enantioselectivity of the reaction was low. Imamoto et al. prepared a new tetraphosphine ligand 19

Primary-tertiary diamine-catalyzed Michael addition of ketones to isatylidenemalononitrile derivatives

• Akshay Kumar and
• Swapandeep Singh Chimni

Beilstein J. Org. Chem. 2014, 10, 929–935, doi:10.3762/bjoc.10.91

• 86% yield and 88% ee (Table 5, entry 9). A recently reported similar reaction catalyzed by Cinchona alkaloid-based primary amine catalyst requires high catalyst loading and is only suitable for N-unprotected isatylidenemalononitrile derivatives [5]. In contrast, our methodology is suitable for both N

Aza-Diels–Alder reaction between N-aryl-1-oxo-1H-isoindolium ions and tert-enamides: Steric effects on reaction outcome

• Amitabh Jha,
• Ting-Yi Chou,
• Zainab ALJaroudi,
• Bobby D. Ellis and
• T. Stanley Cameron

Beilstein J. Org. Chem. 2014, 10, 848–857, doi:10.3762/bjoc.10.81

• -a]isoquinolinone which has been isolated from Berberis darwinii [1][2][3]. Cryptolepine is an indolo[3,2-b]quinolone alkaloid found in west African shrub Cryptolepis sanguinolenta, a plant used in traditional medicine for the treatment of malaria [3]. This alkaloid has shown potent antiplasmodial [4

• ] and anticancer [5] activities. The bioactive β-carboline alkaloids canthinone [6] and vinpocitine [7] also bear these substructures. Vinpocetine is a dehydrated derivative of the natural alkaloid of vincamine [8]. It is reported to have cerebral blood-flow enhancing [7] and neuroprotective effects [9