Bidirectional cross metathesis and ring-closing metathesis/ring opening of a C₂-symmetric building block: a strategy for the synthesis of decanolide natural products

• Bernd Schmidt and
• Oliver Kunz

Beilstein J. Org. Chem. 2013, 9, 2544–2555, doi:10.3762/bjoc.9.289

• ; natural products; ruthenium; Introduction Bidirectional synthesis through termini differentiation of meso, C2-symmetric or unsymmetric building blocks has emerged as an important strategy in natural product synthesis over the past two decades [1]. Early on, enantiomerically pure C2-symmetric compounds

Transition-metal and organocatalysis in natural product synthesis

• David Yu-Kai Chen and
• Dawei Ma

Beilstein J. Org. Chem. 2013, 9, 1192–1193, doi:10.3762/bjoc.9.134

• problems to be investigated. As such, this catalytic cycle of discovery fueled by natural-product synthesis continues to capture and captivate the imagination of both practitioners and students of organic chemistry around the world and will do so far beyond the foreseeable future. In particular, the recent

• natural products, a field of organic chemistry that is both historical and contemporary, has undoubtedly entered a new paradigm over the past decade with the advent of revolutionary new synthetic methods and innovative synthetic concepts. Putting aside the downstream applications of natural-product

• synthesis in the interrogation of biological processes, elucidation of biogenetic origins, structural assignments and many others, its fundamental and indispensable value as a vehicle for the discovery of new synthetic transformations is well-testified and unparalleled by any other research discipline over

Formal synthesis of (−)-agelastatin A: an iron(II)-mediated cyclization strategy

• Daisuke Shigeoka,
• Takuma Kamon and
• Takehiko Yoshimitsu

Beilstein J. Org. Chem. 2013, 9, 860–865, doi:10.3762/bjoc.9.99

• redox states were operative. Keywords: agelastatin; aminohalogenation; iron(II); free radical; natural product synthesis; Introduction Marine organisms often produce bioactive substances that potentially serve as attractive resources for drug discovery. (−)-Agelastatin A (AA, 1), a cytotoxic alkaloid

Alternaric acid: formal synthesis and related studies

• Michael C. Slade and
• Jeffrey S. Johnson

Beilstein J. Org. Chem. 2013, 9, 166–172, doi:10.3762/bjoc.9.19

• endeavors, both in natural-product synthesis and synthetic methodologies [20]. Key to their use in a variety of contexts is the ability of silyl glyoxylates to function as linchpin synthons for geminal coupling of nucleophile/electrophile pairs at a glycolic acid subunit (Scheme 1A), which allows the rapid

Dipyrazolo[1,5-a:4',3'-c]pyridines – a new heterocyclic system accessed via multicomponent reaction

• Wolfgang Holzer,
• Gytė Vilkauskaitė,
• Eglė Arbačiauskienė and
• Algirdas Šačkus

Beilstein J. Org. Chem. 2012, 8, 2223–2229, doi:10.3762/bjoc.8.251

• Wolfgang Holzer Gyte Vilkauskaite Egle Arbaciauskiene Algirdas Sackus Department of Drug and Natural Product Synthesis, Faculty of Life Sciences, University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria Institute of Synthetic Chemistry, Kaunas University of Technology, Radvilėnų pl. 19

Arylglycine-derivative synthesis via oxidative sp³ C–H functionalization of α-amino esters

• Zhanwei Xu,
• Xiaoqiang Yu,
• Xiujuan Feng and
• Ming Bao

Beilstein J. Org. Chem. 2012, 8, 1564–1568, doi:10.3762/bjoc.8.178

• derivatives represent important synthetic intermediates or building blocks for drug development and natural-product synthesis [1][2]. The arylglycine moiety also occurs in several bioactive natural products [3]. Consequently, the development of convenient and efficient methods for the preparation of

Highly enantioselective access to cannabinoid-type tricyles by organocatalytic Diels–Alder reactions

• Stefan Bräse,
• Nicole Volz,
• Franziska Gläser and
• Martin Nieger

Beilstein J. Org. Chem. 2012, 8, 1385–1392, doi:10.3762/bjoc.8.160

• synthesis. Keywords: cannabinoids; Diels–Alder reaction; natural product synthesis; organocatalysis; Introduction The Diels–Alder reaction is one of the most important processes for carbon–carbon-bond formation in organic chemistry [1][2]. Especially in the synthesis of natural products it is a widely

• used method [3][4][5][6][7]. Some examples are shown in Figure 1. The first application was the total synthesis of the steroid Cortisone (1) in 1952 by Woodward et al. [8]. Another example, indicating the importance of the well-known [4 + 2] cycloaddition in natural-product synthesis, is the first

Unprecedented deoxygenation at C-7 of the ansamitocin core during mutasynthetic biotransformations

• Tobias Knobloch,
• Gerald Dräger,
• Wera Collisi,
• Florenz Sasse and
• Andreas Kirschning

Beilstein J. Org. Chem. 2012, 8, 861–869, doi:10.3762/bjoc.8.96

• pursued in industrial research [1][2][3]. Investigations into the biosynthesis of natural products have not only allowed us to understand the synthetic principles that nature pursues, but have also provided tools, mainly based on genetic engineering, which can be exploited in natural product synthesis [4

Stereoselective, nitro-Mannich/lactamisation cascades for the direct synthesis of heavily decorated 5-nitropiperidin-2-ones and related heterocycles

• Pavol Jakubec,
• Dane M. Cockfield,
• Madeleine Helliwell,
• James Raftery and
• Darren J. Dixon

Beilstein J. Org. Chem. 2012, 8, 567–578, doi:10.3762/bjoc.8.64

• to transform it into a general synthetic tool of use in both medicinal chemistry and natural-product synthesis. Results and Discussion To allow us to further explore the nitro-Mannich/lactamisation cascade, a range of Michael adducts 6a–e were synthesised on a gram scale by the reaction of active

• -Mannich/lactamisation cascade to be of use in alkaloid natural-product synthesis (or even simple stereoselective piperidine synthesis), controlled, reductive manipulation of both the nitro group and the lactam carbonyl were required. Although Nef-type oxidation followed by exhaustive reduction of the

Directed aromatic functionalization in natural-product synthesis: Fredericamycin A, nothapodytine B, and topopyrones B and D

• Charles Dylan Turner and
• Marco A. Ciufolini

Beilstein J. Org. Chem. 2011, 7, 1475–1485, doi:10.3762/bjoc.7.171

Cationic gold(I) axially chiral biaryl bisphosphine complex-catalyzed atropselective synthesis of heterobiaryls

• Tetsuro Shibuya,
• Kyosuke Nakamura and
• Ken Tanaka

Beilstein J. Org. Chem. 2011, 7, 944–950, doi:10.3762/bjoc.7.105

• synthesis [1][2][3][4] has attracted significant interest due to its great utility in asymmetric catalysis and natural product synthesis. In 2004, three research groups, including ours, independently reported transition-metal catalyzed asymmetric [2 + 2 + 2] cycloaddition reactions to produce axially chiral

Synthetic applications of gold-catalyzed ring expansions

• David Garayalde and
• Cristina Nevado

Beilstein J. Org. Chem. 2011, 7, 767–780, doi:10.3762/bjoc.7.87

• application of these methodologies into more complex settings, such as natural product synthesis. In summary, gold-catalyzed ring expansions of strained rings can now be considered a mature tool for the construction of molecular complexity and thus are to be incorporated in to the toolbox of the synthetic

Complete transfer of chirality in an intramolecular, thermal [2 + 2] cycloaddition of allene-ynes to form non-racemic spirooxindoles

• Kay M. Brummond and
• Joshua M. Osbourn

Beilstein J. Org. Chem. 2011, 7, 601–605, doi:10.3762/bjoc.7.70

• spirooxindoles for application to natural product synthesis [5][6][7]. Herein, we disclose preliminary results demonstrating a complete transfer of chiral information from a chiral non-racemic allene-yne to form an enantiomerically enriched spirooxindole in a [2 + 2] cycloaddition reaction. Findings This study

An efficient and practical entry to 2-amido-dienes and 3-amido-trienes from allenamides through stereoselective 1,3-hydrogen shifts

• Ryuji Hayashi,
• John B. Feltenberger,
• Andrew G. Lohse,
• Mary C. Walton and
• Richard P. Hsung

Beilstein J. Org. Chem. 2011, 7, 410–420, doi:10.3762/bjoc.7.53

• (for reviews on pericyclic ring-closures see [83][84], for reviews on ring-closure in natural product synthesis see [85][86], for recent examples of 6π-electron electrocyclic ring-closure see [87][88][89][90][91][92][93], for examples on accelerated ring-closures of 1,3,5-hexatrienes see [94][95][96

Ene–yne cross-metathesis with ruthenium carbene catalysts

• Cédric Fischmeister and
• Christian Bruneau

Beilstein J. Org. Chem. 2011, 7, 156–166, doi:10.3762/bjoc.7.22

• acetylene in the presence of ruthenium carbene complexes has been reported [11]. A challenge that has still to be faced is the EYCM starting from acyclic internal olefins. Selected ruthenium catalysts able to perform EYCM. Applications of EYCM with ethylene in natural product synthesis. Interaction of

Recent advances in the development of alkyne metathesis catalysts

• Xian Wu and
• Matthias Tamm

Beilstein J. Org. Chem. 2011, 7, 82–93, doi:10.3762/bjoc.7.12

• natural product synthesis and advanced material science [1]. Alkyne metathesis, which deals with the breaking and making of C–C triple bonds, has only relatively recently become part of the tool box of organic and polymer chemists for the preparation of their target molecules [2][3][4][5][6][7][8][9][10

Palladium- and copper-mediated N-aryl bond formation reactions for the synthesis of biological active compounds

• Carolin Fischer and
• Burkhard Koenig

Beilstein J. Org. Chem. 2011, 7, 59–74, doi:10.3762/bjoc.7.10

• and natural product synthesis, a broad application of catalytic C–N-arylation is highly desirable. Evano et al. recently reviewed copper-mediated C–N-arylation reactions in natural product syntheses and discussed different examples from total synthesis using the arylation of alkylamines, amides

• different biological functions including anti-tumour activity and are used as insulin mimetics. The palladium-catalysed coupling of styrene 20 with sterically demanding N-nucleophiles 21 gave the indole building blocks 22 for the natural product synthesis (Scheme 6). In this case, P(t-Bu)3 was the

The allylic chalcogen effect in olefin metathesis

• Yuya A. Lin and
• Benjamin G. Davis

Beilstein J. Org. Chem. 2010, 6, 1219–1228, doi:10.3762/bjoc.6.140

• factors, such as the nature of the catalyst, steric crowding around the alkene and the directing effects of nearby heteroatoms. These factors are of great importance, especially when optimizing reaction conditions for delicate natural product synthesis or protein modification. Interestingly, the

Synthesis of some novel annulated pyrido[2,3-d]pyrimidines via stereoselective intramolecular hetero Diels–Alder reactions of 1-oxa-1,3-butadienes

• Mohit L. Deb and
• Pulak J. Bhuyan

Beilstein J. Org. Chem. 2010, 6, No. 11, doi:10.3762/bjoc.6.11

• preparation of these complex molecules. However, there still remains many challenges in the synthesis of these naturally occurring complex molecules [22][23][24][25][26][27][28][29][30][31]. Hetero Diels–Alder reactions [32][33][34][35] are becoming a mainstay of heterocyclic and natural product synthesis

A review of new developments in the Friedel–Crafts alkylation – From green chemistry to asymmetric catalysis

• Magnus Rueping and
• Boris J. Nachtsheim

Beilstein J. Org. Chem. 2010, 6, No. 6, doi:10.3762/bjoc.6.6

• would allow the use of the Friedel–Crafts reactions in the late stages of complex natural product synthesis or in the preparation of biological relevant molecules, including pharmaceuticals and agrochemicals. Furthermore, the extension of substrate scope away from π-activated alcohols and double bonds

Reduction of arenediazonium salts by tetrakis(dimethylamino)ethylene (TDAE): Efficient formation of products derived from aryl radicals

• Mohan Mahesh,
• John A. Murphy,
• Franck LeStrat and
• Hans Peter Wessel

Beilstein J. Org. Chem. 2009, 5, No. 1, doi:10.3762/bjoc.5.1

• convenient. Further extensions of this methodology in the construction of several heterocyclic ring systems and complex synthetic targets for natural product synthesis are currently in progress in our laboratory. Aza- and thia-substituted electron donors. Radical-polar crossover reaction of arenediazonium

Vinylogous Mukaiyama aldol reactions with 4-oxy-2-trimethylsilyloxypyrroles: relevance to castanospermine synthesis

• Roger Hunter,
• Sophie C. M. Rees-Jones and
• Hong Su

Beilstein J. Org. Chem. 2007, 3, No. 38, doi:10.1186/1860-5397-3-38

• 16. Structure of 6a with numbering to demonstrate numbering system used in this section. An example of a vinylogous Mukaiyama aldol in a natural product synthesis. Reagents and conditions: a) RCHO 2, SnCl4 (1.2 equiv), ether, -85°C. Our vinylogous Mukaiyama aldol reaction with different substituents

Synthesis of 2,6-trans- disubstituted 5,6-dihydropyrans from (Z)-1,5-syn-endiols

• Eric M. Flamme and
• William R. Roush

Beilstein J. Org. Chem. 2005, 1, No. 7, doi:10.1186/1860-5397-1-7

• enantioselectivity.[1] In connection with an ongoing natural product synthesis project, we were interested in developing methods to transform diols 2 into dihydropyrans 3 or the enantiomeric dihydropyrans ent-3 through complementary, regioselective cyclodehydration processes (Scheme 1). 2,6-Disubstituted