Amino acid motifs in natural products: synthesis of O-acylated derivatives of (2S,3S)-3-hydroxyleucine

• Oliver Ries,
• Martin Büschleb,
• Markus Granitzka,
• Dietmar Stalke and
• Christian Ducho

Beilstein J. Org. Chem. 2014, 10, 1135–1142, doi:10.3762/bjoc.10.113

• opening up an excellent approach for the synthesis of bioactive natural products and derivatives thereof for structure activity relationship (SAR) studies. Keywords: chiral pool; cross metathesis; esterification; β-hydroxy-α-amino acids; natural products; Introduction Besides the proteinogenic β-hydroxy

Preparation of new alkyne-modified ansamitocins by mutasynthesis

• Kirsten Harmrolfs,
• Lena Mancuso,
• Binia Drung,
• Florenz Sasse and
• Andreas Kirschning

Beilstein J. Org. Chem. 2014, 10, 535–543, doi:10.3762/bjoc.10.49

• past two decades. In part, this development is due to their often limited accessibility as well as their structural complexity. This situation hampers their use as lead structures for which access to small compound libraries is essential in order to perform structure–activity relationship studies

• pharmacophore of the maytansinoids. All other derivatives show strong to moderate antiproliferative activity, irrespective whether the lack of the N-methyl group, and or the oxirane groups or not. This is in line with the view obtained from structure–activity relationship studies that these tailoring

The myxocoumarins A and B from Stigmatella aurantiaca strain MYX-030

• Tobias A. M. Gulder,
• Snežana Neff,
• Traugott Schüz,
• Tammo Winkler,
• René Gees and
• Bettina Böhlendorf

Beilstein J. Org. Chem. 2013, 9, 2579–2585, doi:10.3762/bjoc.9.293

• possible. Structure–activity relationship (SAR) studies on synthetic myxocoumarin derivatives as well as in-depth investigation of their antibacterial potential are currently performed in our laboratory and will be reported in due course. Experimental Cultivation and extraction. The preculture of S

Synthesis of homo- and heteromultivalent carbohydrate-functionalized oligo(amidoamines) using novel glyco-building blocks

• Felix Wojcik,
• Sinaida Lel,
• Alexander G. O’Brien,
• Peter H. Seeberger and
• Laura Hartmann

Beilstein J. Org. Chem. 2013, 9, 2395–2403, doi:10.3762/bjoc.9.276

• binding mechanisms as well as structure–activity relationship studies of multivalent glycomaterials is required. Multivalent sugar presentation has been realized on a variety of different scaffolds such as polymers [8][9], dendrimers [10] or naturally-occurring scaffolds such as peptides [11][12][13] or

• important platform for structure–activity relationship studies [15][16][17]. Precision macromolecules combine the advantages of synthetic scaffolds such as polymers with the advantages of naturally-occurring scaffolds such as peptides as they are highly defined, versatile in their structure (linear or

Cyclopamine analogs bearing exocyclic methylenes are highly potent and acid-stable inhibitors of hedgehog signaling

• Johann Moschner,
• Anna Chentsova,
• Nicole Eilert,
• Irene Rovardi,
• Philipp Heretsch and
• Athanassios Giannis

Beilstein J. Org. Chem. 2013, 9, 2328–2335, doi:10.3762/bjoc.9.267

• alkaloids; structure–activity relationship; Introduction Hedgehog signaling is involved in embryonic development and plays an important role in the maintenance of stem cells, tissue repair and regeneration in adult organisms [1][2][3][4]. The erroneous activation of hedgehog signaling is tightly associated

• conditions are summarized in Table 1. Conclusion In conclusion, we succeeded in identifying the new cyclopamine derivative bis-exo-cyclopamine 6 which surpasses the biological potency of the parent compound by the 25-fold and is stable at pH 1. Further insights were gained into the structure–activity

• relationship of F-ring-modified analogs of cyclopamine and the necessity of the C-21 methyl group for bioactivity and acid stability was revealed. Our designed analogs of cyclopamine are accessible in noticeably shorter and higher yielding synthetic routes than the parent compound, a fact that will further

An approach towards azafuranomycin analogs by gold-catalyzed cycloisomerization of allenes: synthesis of (αS,2R)-(2,5-dihydro-1H-pyrrol-2-yl)glycine

• Jörg Erdsack and
• Norbert Krause

Beilstein J. Org. Chem. 2013, 9, 1936–1942, doi:10.3762/bjoc.9.229

• were published [2][5][6][7][8] as well as numerous reports dedicated to derivatives and stereoisomers [9][10][11][12][13][14][15][16][17][18][19][20]. Examination of structure–activity relationship (SAR) revealed a loss of antibiotic activity upon shifting of the methyl group to different positions

Synthesis and quantitative structure–activity relationship study of substituted imidazophosphor ester based tetrazolo[1,5-b]pyridazines as antinociceptive/anti-inflammatory agents

• Wafaa M. Abdou,
• Neven A. Ganoub and
• Eman Sabry

Beilstein J. Org. Chem. 2013, 9, 1730–1736, doi:10.3762/bjoc.9.199

• tested compounds at a dose of 50 mg per kilogram body weight at successive intervals is displayed in Figure 1. According to the results of the biological assay in Table 1, we could deduce the structure–activity relationship (SAR) as follows: (1) among the tested compounds, β-enaminobisphosphonate 15 has

Amyloid-β probes: Review of structure–activity and brain-kinetics relationships

• Todd J. Eckroat,
• Abdelrahman S. Mayhoub and
• Sylvie Garneau-Tsodikova

Beilstein J. Org. Chem. 2013, 9, 1012–1044, doi:10.3762/bjoc.9.116

• , have been widely reported as Aβ-imaging tracers (Scheme 2A). Structure–activity-relationship (SAR) studies on fluorinated chalcones 18a–l have shown that, in general, chalcones with tertiary amines in their structures demonstrate good affinity for Aβ plaques in in vitro models (Ki = 20–50 nM) (Table 1

Design and synthesis of tag-free photoprobes for the identification of the molecular target for CCG-1423, a novel inhibitor of the Rho/MKL1/SRF signaling pathway

• Jessica L. Bell,
• Andrew J. Haak,
• Susan M. Wade,
• Yihan Sun,
• Richard R. Neubig and
• Scott D. Larsen

Beilstein J. Org. Chem. 2013, 9, 966–973, doi:10.3762/bjoc.9.111

• and/or low-abundance targets requires photolabeling [11]. This permits extensive isolation and purification without premature dissociation from the target. Based on the structure–activity relationship (SAR) of 2, we hypothesized that we could integrate photoactivatable functional groups without loss

Recent progress in the discovery of small molecules for the treatment of amyotrophic lateral sclerosis (ALS)

• Allison S. Limpert,
• Margrith E. Mattmann and
• Nicholas D. P. Cosford

Beilstein J. Org. Chem. 2013, 9, 717–732, doi:10.3762/bjoc.9.82

• induced by these lead compounds was found to be functional and exhibit appropriate cellular localization [6]. Using these identified lead compounds, Xing et al. [16] performed chemical optimization to develop additional analogues for potential use as therapeutic agents. Structure–activity relationship

• (Figure 12). In a screen of a chemically diverse compound library, Pieper et al. identified an aminopropyl carbazole, P7C3, which was found to increase adult hippocampal neurogenesis in an in vivo assay [53]. Further optimization of this compound through structure–activity relationship (SAR) analysis led

Synthesis and evaluation of cell-permeable biotinylated PU-H71 derivatives as tumor Hsp90 probes

• Tony Taldone,
• Anna Rodina,
• Erica M. DaGama Gomes,
• Matthew Riolo,
• Hardik J. Patel,
• Raul Alonso-Sabadell,
• Danuta Zatorska,
• Maulik R. Patel,
• Sarah Kishinevsky and
• Gabriela Chiosis

Beilstein J. Org. Chem. 2013, 9, 544–556, doi:10.3762/bjoc.9.60

• inhibit Hsp90 and their structure–activity relationship, less is understood about Hsp90 tumor biology. As a result we and others have been actively engaged in the synthesis of chemical tools designed to probe the function of Hsp90 in transformed systems [9][10][11]. One class of Hsp90 inhibitors of

New GABA amides activating GABA_A-receptors

• Peter Raster,
• Andreas Späth,
• Svetlana Bultakova,
• Pau Gorostiza,
• Burkhard König and
• Piotr Bregestovski

Beilstein J. Org. Chem. 2013, 9, 406–410, doi:10.3762/bjoc.9.42

• GABAA-receptor channels in whole-cell patch-clamp recordings. New GABA-amides, however, gave moderate activation responses with a clear structure–activity relationship suggesting some of these compounds as promising molecular tools for the functional analysis of GABAA-receptors. Keywords: CHO-cells

Asymmetric synthesis of host-directed inhibitors of myxoviruses

• Terry W. Moore,
• Kasinath Sana,
• Dan Yan,
• Pahk Thepchatri,
• John M. Ndungu,
• Manohar T. Saindane,
• Mark A. Lockwood,
• Michael G. Natchus,
• Dennis C. Liotta,
• Richard K. Plemper,
• James P. Snyder and
• Aiming Sun

Beilstein J. Org. Chem. 2013, 9, 197–203, doi:10.3762/bjoc.9.23

• number of myxoviruses [8][12][14]. Structure–activity relationship (SAR) studies suggested both the 2-chloro-4-methylanilide and the central α-thiopropionamide to be moieties that confer good activity. Relatively unexplored in our previous work was the importance of the p-methoxyphenyl ring as well as

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

• , we [20] and others [21] reported an in-depth structure–activity relationship of this natural product against its HDAC targets. Dissection of its activity against a panel of HDACs allowed us to highlight structural features responsible for its high inhibitory potency and selectivity. In particular, we

Intramolecular carbolithiation of N-allyl-ynamides: an efficient entry to 1,4-dihydropyridines and pyridines – application to a formal synthesis of sarizotan

• Wafa Gati,
• Mohamed M. Rammah,
• Mohamed B. Rammah and
• Gwilherm Evano

Beilstein J. Org. Chem. 2012, 8, 2214–2222, doi:10.3762/bjoc.8.250

• clinical trials failed to confirm its efficiency [51], sarizotan is still under intense investigation [52][53][54] and was recently licensed to Newron Pharmaceuticals for further testing in new indications [55]. Motivated by the high potential of sarizotan and by the clear lack of structure-activity

• relationship studies on the pyridine core of this bioactive compound [56], we designed an efficient and modular synthesis of the disubstituted pyridine core of sarizotan that should enable the preparation of sarizotan analogues with different substitution on the pyridine ring. This synthesis is shown in Scheme

Total synthesis and biological evaluation of fluorinated cryptophycins

• Christine Weiß,
• Tobias Bogner,
• Benedikt Sammet and
• Norbert Sewald

Beilstein J. Org. Chem. 2012, 8, 2060–2066, doi:10.3762/bjoc.8.231

• ; fluorinated natural product analogues; structure-activity relationship; Introduction Cryptophycins form a class of cytotoxic sixteen-membered macrocyclic depsipeptides. Cryptophycin-1 (1) was isolated for the first time in 1990 from cyanobacteria Nostoc sp. ATCC 53789 [1] (Figure 1). Moore et al. isolated

• naturally occurring cryptophycins have been isolated up to this day [5][6][7], while numerous synthetic analogues have been synthesized in the frame of structure–activity-relationship studies [8][9]. Cryptophycins display remarkable biological activity against multi-drug-resistant (MDR) tumor cells. Such

• -amino acid, usually β2-homoalanine. Finally, unit D is leucic acid, the hydroxy analogue of leucine. Numerous synthetic analogues have been obtained in the frame of structure–activity-relationship studies (SAR-studies), as reviewed in [17][18]. Unit A para-alkoxymethyl derivatives of cryptophycin-52

Tricyclic flavonoids with 1,3-dithiolium substructure

• Lucian G. Bahrin,
• Peter G. Jones and
• Henning Hopf

Beilstein J. Org. Chem. 2012, 8, 1999–2003, doi:10.3762/bjoc.8.226

• led to the synthesis of derivative 1, a selective estrogen receptor β agonist (SERBA-1, Figure 1) [5]. Studies that focus on the structure–activity relationship were reported [6][7]. It was shown that a cyclopentane ring at the 3,4-carbon positions (labeled C, Figure 1) leads to a substantial rise in

Antifreeze glycopeptide diastereomers

• Lilly Nagel,
• Carsten Budke,
• Axel Dreyer,
• Thomas Koop and
• Norbert Sewald

Beilstein J. Org. Chem. 2012, 8, 1657–1667, doi:10.3762/bjoc.8.190

• whereas the peptides with one or two methylene spacers showed moderate activity. Results and Discussion In the frame of our ongoing studies on the structure–activity relationship of AFGPs, we became interested in the question of whether an inversion of the configuration at Cβ of threonine (replacement of

Organocatalytic asymmetric Michael addition of unprotected 3-substituted oxindoles to 1,4-naphthoquinone

• Jin-Sheng Yu,
• Feng Zhou,
• Yun-Lin Liu and
• Jian Zhou

Beilstein J. Org. Chem. 2012, 8, 1360–1365, doi:10.3762/bjoc.8.157

• because of the wide occurrence of this structural motif in natural products and pharmaceutically active compounds [1][2][3]. In addition, structure–activity relationship studies have revealed that the absolute configuration and the substituent of the C3 position of oxindole greatly influenced the

Parallel and four-step synthesis of natural-product-inspired scaffolds through modular assembly and divergent cyclization

• Hiroki Oguri,
• Haruki Mizoguchi,
• Hideaki Oikawa,
• Aki Ishiyama,
• Masato Iwatsuki,
• Kazuhiko Otoguro and
• Satoshi Ōmura

Beilstein J. Org. Chem. 2012, 8, 930–940, doi:10.3762/bjoc.8.105

• successfully applied to demonstrate the flexibility and scope of the unified four-step process for the generation of structural diversity in the fused scaffolds. Evaluation of in vitro antitrypanosomal activities of the collections and preliminary structure–activity relationship (SAR) studies were also

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

• pharmaceuticals because of their structural complexity and the difficulties associated with accessing analogues for structure–activity relationship studies. Total synthesis approaches are still a tour de force and are hardly employed, while commonly semisynthesis as well as biotechnological approaches are widely

Synthesis and characterization of Sant-75 derivatives as Hedgehog-pathway inhibitors

• Chao Che,
• Song Li,
• Bo Yang,
• Shengchang Xin,
• Zhixiong Yu,
• Taofeng Shao,
• Chuanye Tao,
• Shuo Lin and
• Zhen Yang

Beilstein J. Org. Chem. 2012, 8, 841–849, doi:10.3762/bjoc.8.94

• , Beijing 100871, China 10.3762/bjoc.8.94 Abstract Sant-75 is a newly identified potent inhibitor of the hedgehog pathway. We designed a diversity-oriented synthesis program, and synthesized a series of Sant-75 analogues, which lays the foundation for further investigation of the structure–activity

• relationship of this important class of hedgehog-pathway inhibitors. Keywords: chemical diversity; diversity-oriented; hedgehog pathway; inhibitor; Sant-75; synthesis; Introduction The Hedgehog (Hh) signaling pathway plays an essential role in embryonic development and adult tissue homeostasis in metazoans

An easily accessible sulfated saccharide mimetic inhibits in vitro human tumor cell adhesion and angiogenesis of vascular endothelial cells

• Grazia Marano,
• Claas Gronewold,
• Martin Frank,
• Anette Merling,
• Christian Kliem,
• Sandra Sauer,
• Manfred Wiessler,
• Eva Frei and
• Reinhard Schwartz-Albiez

Beilstein J. Org. Chem. 2012, 8, 787–803, doi:10.3762/bjoc.8.89

• minor variations in its molecular structure, such as the introduction of a second sulfate or the replacement of the sulfate by a halogen, may become even more potent [49]. Further systematic tests are needed to investigate the structure–activity relationship. Experimental General Commercially available

Synthesis of 2-amino-3-arylpropan-1-ols and 1-(2,3-diaminopropyl)-1,2,3-triazoles and evaluation of their antimalarial activity

• Matthias D’hooghe,
• Stéphanie Vandekerckhove,
• Karen Mollet,
• Karel Vervisch,
• Stijn Dekeukeleire,
• Liesbeth Lehoucq,
• Carmen Lategan,
• Peter J. Smith,
• Kelly Chibale and
• Norbert De Kimpe

Beilstein J. Org. Chem. 2011, 7, 1745–1752, doi:10.3762/bjoc.7.205

• )aziridines by diethylamine [8]. Nonetheless, a number of challenges with regard to structure–activity relationship studies of functionalized aminopropanes remain unaddressed, especially concerning the screening of structural analogues of aminopropanes 1 and 2. In the present paper, the synthesis of racemic

• -resistant strain of P. falciparum (Dd2) revealed antiplasmodial activity for 2-aminopropan-1-ol 6a, 2-aminopropan-1,3-diols 9a,b and triaminopropane 16f with IC50-values between 8.5 and 13.6 μM. From a structure–activity relationship viewpoint, the presence of a chlorinated aromatic ring seems to contribute

Synthesis and characterization of new diiodocoumarin derivatives with promising antimicrobial activities

• Hany M. Mohamed,
• Ashraf H. F. Abd EL-Wahab,
• Ahmed M. EL-Agrody,
• Ahmed H. Bedair,
• Fathy A. Eid,
• Mostafa M. Khafagy and
• Kamal A. Abd-EL-Rehem

Beilstein J. Org. Chem. 2011, 7, 1688–1696, doi:10.3762/bjoc.7.199

• , compared with the standards ampicillin and calforan. In addition, compounds 2 and 5 in the series were found to be inactive against Escherichia coli (NCTC-10410), while compound 11 was inactive against Serratia marcescens (IMRU-70). An investigation of the structure–activity relationship (SAR) revealed