Iodine-mediated synthesis of 3-acylbenzothiadiazine 1,1-dioxides

• Long-Yi Xi,
• Ruo-Yi Zhang,
• Lei Shi,
• Shan-Yong Chen and
• Xiao-Qi Yu

Beilstein J. Org. Chem. 2016, 12, 1072–1078, doi:10.3762/bjoc.12.101

• been developed to synthesize benzothiadiazine 1,1-dioxides and their analogues. The condensations of 2-aminobenzenesulfonamides with urea, isocyanates, carboxylic acid derivatives or other carbonyl reagents are the most used methods [12][13][14][15]. These reactions were usually carried out under harsh

A modular approach to neutral P,N-ligands: synthesis and coordination chemistry

• Vladislav Vasilenko,
• Torsten Roth,
• Clemens K. Blasius,
• Sebastian N. Intorp,
• Hubert Wadepohl and
• Lutz H. Gade

Beilstein J. Org. Chem. 2016, 12, 846–853, doi:10.3762/bjoc.12.83

• preparation of the ligand systems L1–L3 on a simple construction principle, i.e., only reactions of carbon- or nitrogen-nucleophiles with chlorophosphines, and condensations of amines with aldehydes were employed. For the synthesis of the N-phosphanylformamidine derivatives 2 and 3 we prepared a set of three

Biosynthesis of α-pyrones

• Till F. Schäberle

Beilstein J. Org. Chem. 2016, 12, 571–588, doi:10.3762/bjoc.12.56

• biosynthesis: The mechanisms of chain elongation resemble each other, and simple building blocks, e.g., acetyl-CoA and malonyl-CoA, are used to build up the molecule [74]. In general both, polyketides and fatty acids are assembled by repeating Claisen-condensations between an activated acyl-starter unit and

Regiodefined synthesis of brominated hydroxyanthraquinones related to proisocrinins

• Joyeeta Roy,
• Tanushree Mal,
• Supriti Jana and
• Dipakranjan Mal

Beilstein J. Org. Chem. 2016, 12, 531–536, doi:10.3762/bjoc.12.52

• biomimetic aldol condensations [17][18][19][20][21][22][23], and reports on the synthesis of brominated anthraquinones are scare [12][13][14][15]. Having inspired by the convergence and the regiochemical integrity of the Hauser annulation [24][25][26][27][28][29][30], we explored it for the construction of

Recent advances in N-heterocyclic carbene (NHC)-catalysed benzoin reactions

• Rajeev S. Menon,
• Akkattu T. Biju and
• Vijay Nair

Beilstein J. Org. Chem. 2016, 12, 444–461, doi:10.3762/bjoc.12.47

• benzoin condensations [18]. The pentafluorophenyltriazolium catalyst 15 featured in the most efficient asymmetric benzoin reaction reported so far. Inoue and co-workers found that it promotes homocoupling of benzaldehyde at a low loading (4 mol %) to afford benzoin in 90% yield and >99% ee (Scheme 6) [19

• have appeared in the literature. They include homo, crossed, intramolecular and various asymmetric benzoin reactions leading to products that are difficult to access by other means. Aza-benzoin reactions, intramolecular benzoin condensations, use of aldehyde surrogates and use of non-carbonyl

• electrophiles (nitroso compounds) are some of the developments that revamped the synthetically unattractive, monotonous image of benzoin condensations. The driving force behind this remarkable evolution of benzoin reaction is NHC-catalysis. Benzoin chemistry is well-set to benefit, in the near future, from new

Recent highlights in biosynthesis research using stable isotopes

• Jan Rinkel and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2015, 11, 2493–2508, doi:10.3762/bjoc.11.271

• may not precisely follow the IUPAC rules. Review Polyketides Polyketide synthases (PKS) are multidomain enzymes that catalyze the formation of natural products via reaction steps similar to fatty acid biosynthesis, in which C2-units are fused in Claisen condensations and modified in an iterative or

Cathodic hydrodimerization of nitroolefins

• Michael Weßling and
• Hans J. Schäfer

Beilstein J. Org. Chem. 2015, 11, 1163–1174, doi:10.3762/bjoc.11.131

• the easy access to nitroolefins in large variety, the C–C bond formation with the introduction of two nitro groups in a 1,4-distance and the conversions of the nitro group by reduction to oximes and amines, the conversion into aldehydes and ketones via the Nef reaction and base catalyzed condensations

Multivalent polyglycerol supported imidazolidin-4-one organocatalysts for enantioselective Friedel–Crafts alkylations

• Tommaso Pecchioli,
• Manoj Kumar Muthyala,
• Rainer Haag and
• Mathias Christmann

Beilstein J. Org. Chem. 2015, 11, 730–738, doi:10.3762/bjoc.11.83

• properties. Hyperbranched polymers like polytriallylsilane or polyglycerol have been used in a wide range of transformations including aldol condensations [22], Suzuki cross-couplings [23] and Diels–Alder reactions [24], to name a few, with metal complexes as catalytically active principle. The advent of

3-Glucosylated 5-amino-1,2,4-oxadiazoles: synthesis and evaluation as glycogen phosphorylase inhibitors

• Marion Donnier-Maréchal,
• David Goyard,
• Vincent Folliard,
• Tibor Docsa,
• Pal Gergely,
• Jean-Pierre Praly and
• Sébastien Vidal

Beilstein J. Org. Chem. 2015, 11, 499–503, doi:10.3762/bjoc.11.56

• corresponding ureas and condensation with C-glucosyl-amidoxime 3 afforded the desired 3-glucosylated 5-amino-1,2,4-oxadiazoles 4a–e in moderate yields. Even though these results are modest, they are in agreement with the yields reported in the literature [29] for such condensations. Removal of the benzoate

The unexpected influence of aryl substituents in N-aryl-3-oxobutanamides on the behavior of their multicomponent reactions with 5-amino-3-methylisoxazole and salicylaldehyde

• Volodymyr V. Tkachenko,
• Elena A. Muravyova,
• Sergey M. Desenko,
• Oleg V. Shishkin,
• Svetlana V. Shishkina,
• Dmytro O. Sysoiev,
• Thomas J. J. Müller and
• Valentin A. Chebanov

Beilstein J. Org. Chem. 2014, 10, 3019–3030, doi:10.3762/bjoc.10.320

• condensations to proceed in various possible directions. The direction control would open pathways for selectively obtaining different classes of heterocyclic compounds [16][17][18][19][20]. Simultaneously, the selectivity will inevitably be dictated by the variation of the reaction conditions [17][18]. Thus

• formation of dihydroisoxazolopyridine 5c (Table 3, entry 8) whereas the analogous reaction under ultrasonication gave exclusively the benzoxazocine derivative 6c (Table 3, entry 9). Interestingly, such a product dichotomy in condensations under or without ultrasonication was not typical for the other

• . Some Biginelli-type three-component condensations with salicylaldehyde. Three-component heterocyclization of 5-amino-3-methylisoxazole (1), salicylaldehyde (2) and N-(2-methoxyphenyl)-3-oxobutanamide (3a). Possible pathways for the three-component reaction of 5-amino-3-methylisoxazole (1

Five-membered ring annelation in [2.2]paracyclophanes by aldol condensation

• Henning Hopf,
• Swaminathan Vijay Narayanan and
• Peter G. Jones

Beilstein J. Org. Chem. 2014, 10, 2021–2026, doi:10.3762/bjoc.10.210

• case. Conclusion In summary, we have demonstrated in this study that aldol-type condensations constitute an attractive alternative to prepare [2.2]paracyclophane derivatives with annelated (and functionalized) five-membered rings, making these derivatives easily available for further transformations

The chemoenzymatic synthesis of clofarabine and related 2′-deoxyfluoroarabinosyl nucleosides: the electronic and stereochemical factors determining substrate recognition by E. coli nucleoside phosphorylases

• Ilja V. Fateev,
• Konstantin V. Antonov,
• Irina D. Konstantinova,
• Tatyana I. Muravyova,
• Frank Seela,
• Roman S. Esipov,
• Anatoly I. Miroshnikov and
• Igor A. Mikhailopulo

Beilstein J. Org. Chem. 2014, 10, 1657–1669, doi:10.3762/bjoc.10.173

• -D-arabinofuranosyl)-2-chloroadenine (1; clofarabine), 2-amino-9-(2-deoxy-2-fluoro-β-D-arabinofuranosyl)adenine (2a) and 9-(2-deoxy-2-fluoro-β-D-arabinofuranosyl)hypoxanthine (3a) are formed in 67, 49 and 21% yields, respectively (Table 1). The condensations of the phosphate 12a with 2-chloroadenine

One-pot three-component synthesis and photophysical characteristics of novel triene merocyanines

• Christian Muschelknautz,
• Robin Visse,
• Jan Nordmann and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2014, 10, 599–612, doi:10.3762/bjoc.10.51

• been accessed by Knoevenagel condensations [12][13][14] or substitution reactions [15][16][17][18]. Still the quest for new synthetic strategies, novel substitution patterns, and eventually unusual properties and effects has become an ongoing challenge for organic synthesis, physical organic chemistry

Isocyanide-based multicomponent reactions towards cyclic constrained peptidomimetics

• Gijs Koopmanschap,
• Eelco Ruijter and
• Romano V.A. Orru

Beilstein J. Org. Chem. 2014, 10, 544–598, doi:10.3762/bjoc.10.50

The Flögel-three-component reaction with dicarboxylic acids – an approach to bis(β-alkoxy-β-ketoenamides) for the synthesis of complex pyridine and pyrimidine derivatives

• Mrinal K. Bera,
• Moisés Domínguez,
• Paul Hommes and
• Hans-Ulrich Reissig

Beilstein J. Org. Chem. 2014, 10, 394–404, doi:10.3762/bjoc.10.37

• . Keywords: alkoxyallenes; condensations; DFT calculations; β-ketoenamides; multi-component reactions; olefin metathesis; pyridines; pyrimidines; Introduction Multicomponent reactions (MCRs) generally allow a diversity-oriented fast and efficient access to complex synthetic intermediates and are thus

• E- and Z-configured enamide moieties [51][52], finally leading to identical products. After these successful multicomponent reactions we investigated the intramolecular condensations of the bis(β-ketoenamides) 13–15 to pyridine and pyrimidine derivatives. Enamides 13 and 14 were treated with

New developments in gold-catalyzed manipulation of inactivated alkenes

• Michel Chiarucci and
• Marco Bandini

Beilstein J. Org. Chem. 2013, 9, 2586–2614, doi:10.3762/bjoc.9.294

• process for the formation of new C–O bonds. In this direction numerous examples of metal and Brønsted-acid catalyzed condensations of alcohols, phenols and carboxylic acids to inactivated olefins have been reported [16]. Interestingly, He and co-workers compared the catalytic attitude of TfOH and

An overview of the synthetic routes to the best selling drugs containing 6-membered heterocycles

• Marcus Baumann and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2013, 9, 2265–2319, doi:10.3762/bjoc.9.265

Raman spectroscopy as a tool for monitoring mesoscale continuous-flow organic synthesis: Equipment interface and assessment in four medicinally-relevant reactions

• Trevor A. Hamlin and
• Nicholas E. Leadbeater

Beilstein J. Org. Chem. 2013, 9, 1843–1852, doi:10.3762/bjoc.9.215

• is assessed by studying four reactions, all involving formation of products bearing α,β-unsaturated carbonyl moieties; synthesis of 3-acetylcoumarin, Knoevenagel and Claisen–Schmidt condensations, and a Biginelli reaction. In each case it is possible to monitor the reactions and also in one case, by

Quantification of N-acetylcysteamine activated methylmalonate incorporation into polyketide biosynthesis

• Stephan Klopries,
• Uschi Sundermann and
• Frank Schulz

Beilstein J. Org. Chem. 2013, 9, 664–674, doi:10.3762/bjoc.9.75

• Polyketides are biosynthesized through consecutive decarboxylative Claisen condensations between a carboxylic acid and differently substituted malonic acid thioesters, both tethered to the giant polyketide synthase enzymes. Individual malonic acid derivatives are typically required to be activated as coenzyme

• widespread application in current medicine and agriculture. Polyketide synthases (PKS), giant multienzyme complexes, play a pivotal role in their biosynthesis. PKS generate molecular complexity and diversity through a number of stepwise condensations in analogy to fatty acid synthases but with optional and

• propionate starter unit with six equivalents of methylmalonyl-coenzyme A (MM-CoA). After six rounds of decarboxylative Claisen condensations and varying degrees of reduction of the initially formed β-keto thioesters, the polyketide core of erythromycin is released from the enzyme via a terminal esterase [6

Flow photochemistry: Old light through new windows

• Jonathan P. Knowles,
• Luke D. Elliott and
• Kevin I. Booker-Milburn

Beilstein J. Org. Chem. 2012, 8, 2025–2052, doi:10.3762/bjoc.8.229

Synthesis of chiral sulfoximine-based thioureas and their application in asymmetric organocatalysis

• Marcus Frings,
• Isabelle Thomé and
• Carsten Bolm

Beilstein J. Org. Chem. 2012, 8, 1443–1451, doi:10.3762/bjoc.8.164

• by three-component condensations of aldehydes, urea-type substrates and enolisable carbonyl compounds. Because of the pharmacological relevance of the products, considerable research has been directed towards asymmetric approaches of these inherently chiral heterocycles [61][62][63]. Until recently

Partial thioamide scan on the lipopeptaibiotic trichogin GA IV. Effects on folding and bioactivity

• Marta De Zotti,
• Barbara Biondi,
• Cristina Peggion,
• Matteo De Poli,
• Haleh Fathi,
• Simona Oancea,
• Claudio Toniolo and
• Fernando Formaggio

Beilstein J. Org. Chem. 2012, 8, 1161–1171, doi:10.3762/bjoc.8.129

• of the 1–8 and the thionated 9–11 segments. For the difficult coupling steps, in particular those involving the segment condensations, the N-[3-(dimethylamino)-propyl]-N'-ethylcarbodiimide (EDC)/7-aza-1-hydroxy-1,2,3-benzotriazole (HOAt) [51] activating method was used, while the EDC/1-hydroxy-1,2,3

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

• 48 in good yields. Despite our concern for the potential instability of the aminoacetal moiety adjacent to the double bond, 47 is stable under the standard manipulations. Overall, the pair of diastereomers generated by the Ugi condensations were converted equally through the unified three-step

An intramolecular inverse electron demand Diels–Alder approach to annulated α-carbolines

• Zhiyuan Ma,
• Feng Ni,
• Grace H. C. Woo,
• Sie-Mun Lo,
• Philip M. Roveto,
• Scott E. Schaus and
• John K. Snyder

Beilstein J. Org. Chem. 2012, 8, 829–840, doi:10.3762/bjoc.8.93

• existing indole framework. In general, applications of this construction sequence fall into two major camps, namely condensations routed through a 2-aminoindole synthon [49][50][51][52][53][54][55][56], and those targeting pyridine closures onto a 2-oxindole [57][58]. In addition, intramolecular Hartwig

Syntheses and applications of furanyl-functionalised 2,2’:6’,2’’-terpyridines

• Jérôme Husson and
• Michael Knorr

Beilstein J. Org. Chem. 2012, 8, 379–389, doi:10.3762/bjoc.8.41

• [19][21] was tested, since it is known to be an efficient promoter of aldol condensations and Michael additions under solvent-free conditions [22][23]. Nevertheless, the treatment of furanyl-substituted aldehydes 1, 3 and 15 did not yield the targeted diketo-intermediates, but instead the chalcones 5