Generation of multimillion chemical space based on the parallel Groebke–Blackburn–Bienaymé reaction

• Evgen V. Govor,
• Vasyl Naumchyk,
• Ihor Nestorak,
• Dmytro S. Radchenko,
• Dmytro Dudenko,
• Yurii S. Moroz,
• Olexiy D. Kachkovsky and
• Oleksandr O. Grygorenko

Beilstein J. Org. Chem. 2024, 20, 1604–1613, doi:10.3762/bjoc.20.143

• last two decades, the GBB reaction has been studied in more than 200 research papers [21] and a number of works (including the original publication by Blackburn and coauthors [20]) described its parallel synthesis version [24][25][26][27][28][29]. Recently, we have shown that other (pseudo-)three

• demonstrating poor performance. Using the resulting sets of amino heterocycles 1{22–485}, aldehydes 2{4–867}, and isonitriles 3{4–78}, 892 library members 4{22–485,4–867,4–78} were deliberately selected and subjected to the parallel synthesis using the Sc(OTf)3-based protocol. As a result, 790 library members

• , is a powerful tool for the combinatorial synthesis of compound libraries. We have shown that the Sc(OTf)3-catalyzed version of the reaction has a wide substrate applicability and established some limitations under the parallel synthesis conditions. In particular, while the method was applicable to a

Stereoselective synthesis and transformation of pinane-based 2-amino-1,3-diols

• Ákos Bajtel,
• Mounir Raji,
• Matti Haukka,
• Ferenc Fülöp and
• Zsolt Szakonyi

Beilstein J. Org. Chem. 2021, 17, 983–990, doi:10.3762/bjoc.17.80

• oxazolidin-2-one 9. NOESY experiments and X-ray structure proofment of the structure of oxazolidine 17. Proposed pathway for the ring–ring tautomerism. Stereoselective synthesis of the pinane-fused oxazolidin-2-one 9. Stereoselective synthesis of the pinane spiro-fused oxazolidin-2-one 12. Parallel synthesis

Microwave-assisted multicomponent reactions in heterocyclic chemistry and mechanistic aspects

• Shivani Gulati,
• Stephy Elza John and
• Nagula Shankaraiah

Beilstein J. Org. Chem. 2021, 17, 819–865, doi:10.3762/bjoc.17.71

• , multimode microwave reactors for parallel synthesis and multimode microwave reactors for single-batch scale-up. The reactors vary in capacity and the distribution mode of the electromagnetic wave in the reactor vessel. The introduction of the Si–C (silicon–carbon) vials enables high temperature resistance

A chromatography-free and aqueous waste-free process for thioamide preparation with Lawesson’s reagent

• Ke Wu,
• Yichen Ling,
• An Ding,
• Liqun Jin,
• Nan Sun,
• Baoxiang Hu,
• Zhenlu Shen and
• Xinquan Hu

Beilstein J. Org. Chem. 2021, 17, 805–812, doi:10.3762/bjoc.17.69

• ]. This method with long perfluorinated alkyl chains is attractive in parallel synthesis and also in high-throughput biological screening. However, both the modified LR and the fluorous solvents are rather expensive and not practical for scaling up. Besides, basic aqueous solutions were utilized as well

A chemically contiguous hapten approach for a heroin–fentanyl vaccine

• Yoshihiro Natori,
• Candy S. Hwang,
• Lucy Lin,
• Lauren C. Smith,
• Bin Zhou and
• Kim D. Janda

Beilstein J. Org. Chem. 2019, 15, 1020–1031, doi:10.3762/bjoc.15.100

• , 86%; c) H2NNH2, EtOH, 89%; d) 1-phenethylpiperidin-4-one, NaBH(OAC)3, AcOH, 0 °C to rt, 92%. General outline of HF-5, HF-8, HF-9 synthesis from fentanyl intermediates 28 and 46, and heroin intermediates 16, and 36. Parallel synthesis of fentanyl domains 25 and 34, for HF-4 and HF-6, respectively

A practical and efficient approach to imidazo[1,2-a]pyridine-fused isoquinolines through the post-GBB transformation strategy

• Taofeng Shao,
• Zhiming Gong,
• Tianyi Su,
• Wei Hao and
• Chao Che

Beilstein J. Org. Chem. 2017, 13, 817–824, doi:10.3762/bjoc.13.82

• the application in parallel synthesis and combinatorial chemistry. Experimental Typical procedure for the GBB multicomponent reaction. To a solution of 2-aminopyridine (1a, 0.5 mmol), 2-ethynylbenzaldehyde (2a, 0.5 mmol), and tert-butylisocyanide (3, 0.6 mmol) in 1 mL of methanol were added p

Facile synthesis of indolo[3,2-a]carbazoles via Pd-catalyzed twofold oxidative cyclization

• Chao Yang,
• Kai Lin,
• Lan Huang,
• Wei-dong Pan and
• Sheng Liu

Beilstein J. Org. Chem. 2016, 12, 2490–2494, doi:10.3762/bjoc.12.243

• dibromobenzoic acid with sulfuric acid in methanol) with an excess of anilines in the presence of cesium carbonate and catalytic quantities of Pd(OAc)2 and BINAP were processed smoothly. The desired methyl 2,4-dianilinobenzoates (2a–e) were obtained in good to excellent yield. In a parallel synthesis, using the

Enabling technologies and green processes in cyclodextrin chemistry

• Giancarlo Cravotto,
• Marina Caporaso,
• Laszlo Jicsinszky and
• Katia Martina

Beilstein J. Org. Chem. 2016, 12, 278–294, doi:10.3762/bjoc.12.30

• interfaced with autosamplers and that new MW reactors can accommodate multiple racks, this technique is well suited for fast optimization of organic protocols and parallel synthesis. The most impressive advantage of the MW technology is the appearance of the kilolab-scale reactors and their special versions

Synthesis of antibacterial 1,3-diyne-linked peptoids from an Ugi-4CR/Glaser coupling approach

• Martin C. N. Brauer,
• Ricardo A. W. Neves Filho,
• Bernhard Westermann,
• Ramona Heinke and
• Ludger A. Wessjohann

Beilstein J. Org. Chem. 2015, 11, 25–30, doi:10.3762/bjoc.11.4

• development of a combinatorial version of the copper-catalysed homodimerization. In this strategy two or more alkyne peptoids should couple simultaneously in the same reaction vessel in order to generate small libraries of dimers. In contrast to parallel synthesis, the combinatorial approach easily generates

Automated solid-phase peptide synthesis to obtain therapeutic peptides

• Veronika Mäde,
• Sylvia Els-Heindl and
• Annette G. Beck-Sickinger

Beilstein J. Org. Chem. 2014, 10, 1197–1212, doi:10.3762/bjoc.10.118

• . reported the parallel synthesis of different peptides, which was performed at polystyrene-based polymers welded in a polypropylene network [62]. Each so called 'tea bag' thereby reflects one independent peptide. In this method, collective deprotection and washing are carried out in a polyethylene (PE

• parallel by a combination of building blocks creating a peptide library [75]. The first parallel synthesis of hundreds of peptides was published by Geysen et al. in 1984 [64]. Here, a series of peptide epitopes was synthesized on a multipin instrument and used for an enzymatic assay. Peptide libraries can

• be created by directed parallel synthesis or complex peptide mixtures and identified by iterative processes or position screenings [63]. A polymer-bound peptide library can be produced by the 'one bead one compound' concept [76]. Here, each solid particle serves as a compartment to assemble an

Silver and gold-catalyzed multicomponent reactions

• Giorgio Abbiati and
• Elisabetta Rossi

Beilstein J. Org. Chem. 2014, 10, 481–513, doi:10.3762/bjoc.10.46

• synthetic strategy, a solution-phase parallel synthesis of 1,2-dihydroisoquinolines has been developed by Larock, providing a 105-membered library for biological assays [58]. Moreover, an extension to γ-ketoalkyne encompassed in diverse heterocyclic frameworks (quinoline, pyridine or benzo[b]thiophene) has

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

• making more efficient use of the light, productivities were increased to 1.8 mmol/h per tube. Additionally, it was demonstrated that the ten capillaries could be used either for parallel synthesis or, by performing the same reaction in each capillary, a single product could be formed at up to 18 mmol/h

Automated three-component synthesis of a library of γ-lactams

• Erik Fenster,
• David Hill,
• Oliver Reiser and
• Jeffrey Aubé

Beilstein J. Org. Chem. 2012, 8, 1804–1813, doi:10.3762/bjoc.8.206

• ; maleimide; organocatalysis; parallel synthesis; reductive amination; Introduction In recent years, the rapid access to structurally diverse and complex small molecules has grown in importance within the context of high-throughput screening of biologically relevant targets. The need for such compounds, both

• efficient for parallel synthesis. If N-phenylmaleimide (1{1}) was to be used as a limiting reagent and propionaldehyde (2{1}) and aniline (4{1}) were used (with 4{1} in excess relative to 2{1}), then at the end of the one-pot process we should be left with the desired γ-lactam 6{1,1,1} and with only amines

• , the γ-lactam 6{1,1,1} was obtained in 66% yield (with 80% es; % es = % major enantiomer, corresponding to 60% ee). Overall, the above-mentioned one-pot sequence, in which both workups and purifications are minimized, proved serviceable in the desired parallel-synthesis sequence. Parallel library

Parallel solid-phase synthesis of diaryltriazoles

• Matthias Wrobel,
• Jeffrey Aubé and
• Burkhard König

Beilstein J. Org. Chem. 2012, 8, 1027–1036, doi:10.3762/bjoc.8.115

• of water occurred in the presence of TFA. The dehydrated products were obtained in 57 and 71%. The remaining material was the corresponding hydroxylated product. Parallel synthesis of a compound library A larger compound library was prepared by using resins 7 and 9, 15 different terminal alkynes 10f

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

• cycloadditions with the dipolarophiles installed at modules 3 and 4 leading to either tetracyclic 14 or hexacyclic 13. In this full account, we also employ a piperidine-based manifold 15 bearing an amino group in order to expand the applicability of the various building blocks in the four-step parallel synthesis

A new and facile synthetic approach to substituted 2-thioxoquinazolin-4-ones by the annulation of a pyrimidine derivative

• Nimalini D. Moirangthem and
• Warjeet S. Laitonjam

Beilstein J. Org. Chem. 2010, 6, 1056–1060, doi:10.3762/bjoc.6.120

• -one libraries by solid-phase synthesis has been reported [19][20][21]. There are two approaches for the solution-phase parallel synthesis of 2-thioxoquinazolin-4-ones [22]. The first approach is based on the reaction of methyl anthranilates with isothiocyanates in refluxing pyridine or DMF. The second

9,10-Dioxa-1,2-diaza-anthracene derivatives from tetrafluoropyridazine

• Graham Pattison,
• Graham Sandford,
• Dmitrii S. Yufit,
• Judith A. K. Howard,
• John A. Christopher and
• David D. Miller

Beilstein J. Org. Chem. 2010, 6, No. 45, doi:10.3762/bjoc.6.45

• heterocyclic compounds with the aim of exploring chemical ‘drug-like’ space [1] and uncovering valuable biological activity for hit-to-lead generation of new chemical entities by parallel synthesis techniques. The wide variety of relatively simple heterocyclic structural types that have not been synthesised [2

• ready synthesis of new organic frameworks is still required and, in this context, heterocyclic scaffolds based on novel molecular architecture that bear multiple functionality and can be rapidly processed into many analogues by parallel synthesis are particularly valuable [5][6]. In a continuing

Asymmetric reactions in continuous flow

• Xiao Yin Mak,
• Paola Laurino and
• Peter H. Seeberger

Beilstein J. Org. Chem. 2009, 5, No. 19, doi:10.3762/bjoc.5.19

• significantly higher when compared to a carousel-type reactor typically used for parallel synthesis. Organocatalytic asymmetric aldol reactions in microflow devices were recently reported by our laboratory [15]. The aldol condensation of various aromatic aldehydes with acetone was carried out at higher

Perhalogenated pyrimidine scaffolds. Reactions of 5-chloro- 2,4,6-trifluoropyrimidine with nitrogen centred nucleophiles

• Emma L. Parks,
• Graham Sandford,
• John A. Christopher and
• David D. Miller

Beilstein J. Org. Chem. 2008, 4, No. 22, doi:10.3762/bjoc.4.22

• in parallel synthesis. 5-Chloro-2,4,6-trifluoropyrimidine may be used as a scaffold for the synthesis of polyfunctional pyrimidine systems if sequential nucleophilic aromatic substitution processes are regioselective. Results Use of 5-chloro-2,4,6-trifluoropyrimidine as a core scaffold for the

• these reactions are not regiospecific and, furthermore, there is an added difficulty of synthesizing a range of structurally related pyrimidine analogues by parallel synthesis or rapid analogue synthesis (RAS) techniques [6][7] due to the limited range of non-cyclic polyfunctional precursors available

• methodology that allows the synthesis of polysubstituted pyrimidine derivatives that are regioselective in all sequential nucleophilic aromatic substitution stages to meet the demands of RAS techniques for applications in parallel synthesis. We are exploring the use of polyhalogenated heteroaromatic systems

ADDP and PS-PPh₃: an efficient Mitsunobu protocol for the preparation of pyridine ether PPAR agonists

• Paul S. Humphries,
• Quyen-Quyen T. Do and
• David M. Wilhite

Beilstein J. Org. Chem. 2006, 2, No. 21, doi:10.1186/1860-5397-2-21

• protocol, which eliminated significant by-product formation. This method proved to be versatile, efficient and amenable to parallel synthesis. Findings Peroxisome proliferator-activated receptors (PPARs) are pharmaceutical targets of great importance. Their wide-ranging effects on key transcriptional

• modified Mitsunobu coupling of pyridinols and alcohols proved to be versatile, efficient and amenable to parallel synthesis. A full account of the medicinal chemistry of these compounds will be given elsewhere. Thiazolidine-2,4-dione mimic & chosen lead scaffold. Proposed mechanism of the Mitsunobu