Synthesis of the tetrasaccharide repeating unit of the O-specific polysaccharide of Azospirillum doebereinerae type strain GSF71^T using linear and one-pot iterative glycosylations

• Arin Gucchait,
• Pradip Shit and
• Anup Kumar Misra

Beilstein J. Org. Chem. 2020, 16, 1700–1705, doi:10.3762/bjoc.16.141

• Arin Gucchait Pradip Shit Anup Kumar Misra Bose Institute, Division of Molecular Medicine, P-1/12, C.I.T. Scheme VII M, Kolkata 700054, India 10.3762/bjoc.16.141 Abstract A straightforward synthetic strategy was developed for the synthesis of the tetrasaccharide repeating unit corresponding to

• the O-specific polysaccharide of Azospirillum doebereinerae type strain GSF71T in a very good yield adopting sequential glycosylation followed by removal of the p-methoxybenzyl (PMB) group in the same pot. Further, the synthetic strategy was modified by carrying out three stereoselective iterative

• ). Having obtained the tetrasaccharide derivative 7 in a very good yield in a minimum number of steps by the sequential synthetic strategy, we decided to explore the possibility of achieving compound 7 by carrying out three iterative glycosylation steps and in situ removal of the PMB groups from the

Synthesis of Streptococcus pneumoniae serotype 9V oligosaccharide antigens

• Sharavathi G. Parameswarappa,
• Claney L. Pereira and
• Peter H. Seeberger

Beilstein J. Org. Chem. 2020, 16, 1693–1699, doi:10.3762/bjoc.16.140

• . Here, we demonstrate a convergent [2 + 3] synthetic strategy to prepare the pentasaccharide repeating unit of 9V with and without an acetate group at the C-6 position of mannosamine. Keywords: antigen; carbohydrate chemistry; oligosaccharide; Streptococcus pneumoniae; vaccines; Introduction

Azidophosphonium salt-directed chemoselective synthesis of (E)/(Z)-cinnamyl-1H-triazoles and regiospecific access to bromomethylcoumarins from Morita–Baylis–Hillman adducts

• Soundararajan Karthikeyan,
• Radha Krishnan Shobana,
• Kamarajapurathu Raju Subimol,
• J. Helen Ratna Monica and
• Ayyanoth Karthik Krishna Kumar

Beilstein J. Org. Chem. 2020, 16, 1579–1587, doi:10.3762/bjoc.16.130

• developing a one-pot synthetic strategy will be worthwhile for pharmacologically important triazoles, such as isavuconazole, tazobactam, and ravuconazole [35]. Results and Discussion Initially, phosphonium salts were barely utilised or exploited in synthetic transformations. Later, in 2014, several organic

In silico rationalisation of selectivity and reactivity in Pd-catalysed C–H activation reactions

• Liwei Cao,
• Mikhail Kabeshov,
• Steven V. Ley and
• Alexei A. Lapkin

Beilstein J. Org. Chem. 2020, 16, 1465–1475, doi:10.3762/bjoc.16.122

• (re)discovered transformations, that are of potential high industrial significance, and where one can observe the same problem of a lack of robustness. Thus, any approach that may speed-up the transition from a discovery of a new transformation to it becoming a robust synthetic strategy, is highly

One-step route to tricyclic fused 1,2,3,4-tetrahydroisoquinoline systems via the Castagnoli–Cushman protocol

• Aleksandar Pashev,
• Nikola Burdzhiev and
• Elena Stanoeva

Beilstein J. Org. Chem. 2020, 16, 1456–1464, doi:10.3762/bjoc.16.121

• substituted benzo[a]quinolizidinones and pyrrolo[2,1-a]isoquinolinones. This reaction also would allow the construction of bioisosteric oxygen and sulfur derivatives of the target heterocyclic framework. Results and Discussion Our synthetic strategy relied on the possibility to form ring C of the target ring

One-pot synthesis of 1,3,5-triazine-2,4-dithione derivatives via three-component reactions

• Gui-Feng Kang and
• Gang Zhang

Beilstein J. Org. Chem. 2020, 16, 1447–1455, doi:10.3762/bjoc.16.120

• and orthoformates and provided a rapid entry to a variety of 4-aryl-6-(alkylthio)-3,4-dihydro-1,3,5-triazine-2(1H)-thiones (29 examples). The synthetic strategy relies on the dual role of thiourea in the cyclization with the aldehydes and the alkylation via an intermediate imidate formation. The

Recent synthesis of thietanes

• Jiaxi Xu

Beilstein J. Org. Chem. 2020, 16, 1357–1410, doi:10.3762/bjoc.16.116

Recent applications of porphyrins as photocatalysts in organic synthesis: batch and continuous flow approaches

• Rodrigo Costa e Silva,
• Luely Oliveira da Silva,
• Aloisio de Andrade Bartolomeu,
• Timothy John Brocksom and
• Kleber Thiago de Oliveira

Beilstein J. Org. Chem. 2020, 16, 917–955, doi:10.3762/bjoc.16.83

• ) (Scheme 34) [82]. The most recent approach for artemisinin synthesis was described by Wang, Zhou and co-workers [83][84] using porphyrin-based MOFs to produce singlet oxygen, and then repeating the same synthetic strategy for artemisinin production (starting from artemisinic acid). Photooxygenation

• rearrangement (Scheme 39) [89]. Further photochemical [2 + 2] cycloaddition and hydrolysis allowed them to obtain rhodonoid A in 30% overall yield. Other similar natural products (rhodonoid B, E and F) were also prepared by the same synthetic strategy. Singlet oxygen has also been efficiently used for

Microwave-assisted efficient and facile synthesis of tetramic acid derivatives via a one-pot post-Ugi cascade reaction

• Yong Li,
• Zheng Huang,
• Jia Xu,
• Yong Ding,
• Dian-Yong Tang,
• Jie Lei,
• Hong-yu Li,
• Zhong-Zhu Chen and
• Zhi-Gang Xu

Beilstein J. Org. Chem. 2020, 16, 663–669, doi:10.3762/bjoc.16.63

• ][28][29] of complex heterocyclic compounds. Recent advance has been focused in the area toward the development of one-pot [30][31][32] Ugi cascade protocol [33][34] as the powerful synthetic strategy for the construction of increasingly complex heterocyclic compounds in the absence of metal catalysts

• filtered. The filtrate was concentrated, which gave a residue that was purified by silica gel column chromatography (ethyl acetate/hexane, 10–60%) to afford the product 7a–l. Structures of natural tetramic acid derivatives with more clinical relevance. Synthetic strategy of compound 7a. Scope of the Ugi

Design and synthesis of diazine-based panobinostat analogues for HDAC8 inhibition

• Sivaraman Balasubramaniam,
• Sajith Vijayan,
• Liam V. Goldman,
• Xavier A. May,
• Kyra Dodson,
• Sweta Adhikari,
• Fatima Rivas,
• Davita L. Watkins and
• Shana V. Stoddard

Beilstein J. Org. Chem. 2020, 16, 628–637, doi:10.3762/bjoc.16.59

• role of the electronic effects of the nitrogen atoms on this cyclic substrate, and then we revised our synthetic strategy by a) tethering an alkene functional group on the aromatic ring and b) then conducting the oxidation of the benzylic group to afford the aldehyde product. Towards this end, we

• the key intermediate aldehyde 25 (Scheme 4). Initially, we explored the Suzuki coupling reaction for substrate 4. Gratifyingly, the reaction product 24 was produced in 41% yield from our developed synthetic strategy. Then, compound 24 was subjected to an SeO2 oxidation reaction. The oxidation reaction

• investigation provides a successful synthetic strategy towards four new analogues of panobinostat having diazines as the central core and details the results of their biochemical evaluation. Computational data corroborated that the substitution of benzene in the molecular framework of panobinostat for a

A systematic review on silica-, carbon-, and magnetic materials-supported copper species as efficient heterogeneous nanocatalysts in “click” reactions

• Pezhman Shiri and
• Jasem Aboonajmi

Beilstein J. Org. Chem. 2020, 16, 551–586, doi:10.3762/bjoc.16.52

• combination of chitosan (137) and laponite® RD (132) [99]. The synthetic strategy to this catalyst is shown in Scheme 29. At first, Fe(II)/Fe(III)-loaded laponite RD, 133, was prepared by adding a solution of Fe(II)/Fe(III) ions to a dispersed solution of 132. In the next step, a solution of 137 was added to

Recent developments in photoredox-catalyzed remote ortho and para C–H bond functionalizations

• Rafia Siddiqui and
• Rashid Ali

Beilstein J. Org. Chem. 2020, 16, 248–280, doi:10.3762/bjoc.16.26

• products was assembled with moderate to high yields using this powerful synthetic strategy, and the scope of the reaction can be seen in Scheme 12. C–H trifluoromethylation The introduction of a CF3 group into pharmaceutical agents can enhance their performance in medicinal chemistry [129][130][131]. In

Combination of multicomponent KA² and Pauson–Khand reactions: short synthesis of spirocyclic pyrrolocyclopentenones

• Riccardo Innocenti,
• Elena Lenci,
• Gloria Menchi and
• Andrea Trabocchi

Beilstein J. Org. Chem. 2020, 16, 200–211, doi:10.3762/bjoc.16.23

• . Following our interest to DOS as a synthetic strategy for the generation of molecular scaffolds according to a couple/pair approach [45][46][47], we reasoned to combine the copper-catalyzed ketone–amine–alkyne (KA2) multicomponent coupling reaction [48] with the Pauson–Khand cycloaddition as the pairing

Convenient synthesis of the pentasaccharide repeating unit corresponding to the cell wall O-antigen of Escherichia albertii O4

• Tapasi Manna,
• Arin Gucchait and
• Anup Kumar Misra

Beilstein J. Org. Chem. 2020, 16, 106–110, doi:10.3762/bjoc.16.12

• Tapasi Manna Arin Gucchait Anup Kumar Misra Bose Institute, Division of Molecular Medicine, P-1/12, C.I.T. Scheme VII M, Kolkata 700054, India 10.3762/bjoc.16.12 Abstract A straightforward sequential synthetic strategy has been developed for the synthesis of a pentasaccharide repeating unit

• of pentasaccharide 1 was achieved using a convergent as well as a block synthetic strategy. For this purpose, a series of suitably functionalized monosaccharide intermediates 2 [20], 3 [21], 4 [22], 5 [23], 6 [24] and 7 [25] were prepared from the commercially available reducing sugars utilizing the

• intermediates, it was decided to proceed through a step-economic block synthetic strategy to achieve the target pentasaccharide derivative. Accordingly, stereoselective glycosylation of a ᴅ-galactosamine derivative 2 with a ᴅ-galactose thioglycoside derivative 3 in the presence of a combination [26][27] of N

Understanding the role of active site residues in CotB2 catalysis using a cluster model

• Keren Raz,
• Ronja Driller,
• Thomas Brück,
• Bernhard Loll and
• Dan T. Major

Beilstein J. Org. Chem. 2020, 16, 50–59, doi:10.3762/bjoc.16.7

• provide important information to derive a synthetic strategy for cyclooctatin and related terpene manufacturing. Future studies using hybrid quantum mechanics and molecular mechanics techniques to model the enzyme reaction in a complete enzyme environment will allow careful evaluation of the usefulness of

Starazo triple switches – synthesis of unsymmetrical 1,3,5-tris(arylazo)benzenes

• Andreas H. Heindl and
• Hermann A. Wegner

Beilstein J. Org. Chem. 2020, 16, 22–31, doi:10.3762/bjoc.16.4

• four phenyl rings were sufficient for the construction of three individually photoisomerizable azo units. Motivated by the promising theoretical results by Dreuw and co-workers [12], an efficient synthetic strategy for asymmetric tris(arylazo)benzenes 3 was developed. With an efficient preparative

• . Synthetic strategy towards 1,3,5-tris(arylazo)benzenes 3 based on consecutive Baeyer–Mills reactions. Preparation of tris(arylazo)benzenes 3 by Pd-catalyzed cross-coupling reactions of N-Boc-arylhydrazides and bromo-substituted ABs, followed by oxidation. Synthesis of azobenzene building block 8. Synthesis

Chemical synthesis of tripeptide thioesters for the biotechnological incorporation into the myxobacterial secondary metabolite argyrin via mutasynthesis

• David C. B. Siebert,
• Roman Sommer,
• Domen Pogorevc,
• Michael Hoffmann,
• Silke C. Wenzel,
• Rolf Müller and
• Alexander Titz

Beilstein J. Org. Chem. 2019, 15, 2922–2929, doi:10.3762/bjoc.15.286

• sarcosine moiety could be obtained. To overcome the high reactivity of the Dha moiety towards nucleophiles, we engaged in an alternative synthetic strategy towards the tripeptide thioester carrying the native sequence ᴅ-Ala-Dha-Sar by designing a convergent synthesis to mutasynthon 14 (Scheme 2). First, Boc

Diversity-oriented synthesis of spirothiazolidinediones and their biological evaluation

• Sambasivarao Kotha,
• Gaddamedi Sreevani,
• Lilya U. Dzhemileva,
• Milyausha M. Yunusbaeva,
• Usein M. Dzhemilev and
• Vladimir A. D’yakonov

Beilstein J. Org. Chem. 2019, 15, 2774–2781, doi:10.3762/bjoc.15.269

• ][28]. In view of the importance of thiazolidine-2,4-dione derivatives, we conceived a new synthetic strategy to diverse spirocyclic thiazolidinediones based on a [2 + 2 + 2] cyclotrimerization [29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49][50][51] as a key step

A toolbox of molecular photoswitches to modulate the CXCR3 chemokine receptor with light

• Xavier Gómez-Santacana,
• Sabrina M. de Munnik,
• Tamara A. M. Mocking,
• Niels J. Hauwert,
• Shanliang Sun,
• Prashanna Vijayachandran,
• Iwan J. P. de Esch,
• Henry F. Vischer,
• Maikel Wijtmans and
• Rob Leurs

Beilstein J. Org. Chem. 2019, 15, 2509–2523, doi:10.3762/bjoc.15.244

• , 1–2 h, 68–97%; (e) i) Et3N (1.1–1.6 equiv), DCM, rt, 10–30 min; ii) NaBH(OAc)3 (1.6 equiv), rt, 6–16 h, 69–96%; (f) MeI (20 equiv), DCM, rt, 6–72 h, 79–95%. Synthetic strategy for compound 6e. Reagents and conditions: (a) i) K2CO3 (2.0 equiv), DMF, µW, 65 °C, 3 h; ii) AcOH, reflux, 1 h, 67%; (b) i

Recent advances in transition-metal-catalyzed incorporation of fluorine-containing groups

• Xiaowei Li,
• Xiaolin Shi,
• Xiangqian Li and
• Dayong Shi

Beilstein J. Org. Chem. 2019, 15, 2213–2270, doi:10.3762/bjoc.15.218

N-(1-Phenylethyl)aziridine-2-carboxylate esters in the synthesis of biologically relevant compounds

• Iwona E. Głowacka,
• Aleksandra Trocha,
• Andrzej E. Wróblewski and
• Dorota G. Piotrowska

Beilstein J. Org. Chem. 2019, 15, 1722–1757, doi:10.3762/bjoc.15.168

Recent advances on the transition-metal-catalyzed synthesis of imidazopyridines: an updated coverage

• Gagandeep Kour Reen,
• Ashok Kumar and
• Pratibha Sharma

Beilstein J. Org. Chem. 2019, 15, 1612–1704, doi:10.3762/bjoc.15.165

Anomeric sugar boronic acid analogues as potential agents for boron neutron capture therapy

• Daniela Imperio,
• Erika Del Grosso,
• Silvia Fallarini,
• Grazia Lombardi and
• Luigi Panza

Beilstein J. Org. Chem. 2019, 15, 1355–1359, doi:10.3762/bjoc.15.135

• conserved into the analogues). Structures of boron analogues. Synthetic strategy. Postulated transition states for the hydroboration reaction. Synthesis of 2-deoxy analogue 8. Synthesis of 2,3-dideoxy analogue 11. Supporting Information Supporting Information File 488: Experimental procedures and

Synthesis of dipolar molecular rotors as linkers for metal-organic frameworks

• Sebastian Hamer,
• Fynn Röhricht,
• Marius Jakoby,
• Ian A. Howard,
• Xianghui Zhang,
• Christian Näther and
• Rainer Herges

Beilstein J. Org. Chem. 2019, 15, 1331–1338, doi:10.3762/bjoc.15.132

• orientation of the dipoles. The calculated dipole moment µ of the rotor (chemical structure on top left) is 8.6 D. Structures of molecular dipolar rotors/linker molecules 1–5. General synthetic strategy to prepare the dipolar rotors 1–5. Synthesis of 3,3'-(2,3-difluoro-1,4-phenylene)dipropiolic acid (1

Steroid diversification by multicomponent reactions

• Leslie Reguera,
• Cecilia I. Attorresi,
• Javier A. Ramírez and
• Daniel G. Rivera

Beilstein J. Org. Chem. 2019, 15, 1236–1256, doi:10.3762/bjoc.15.121

• . This could indicate that the antifungal properties of such azasteroids very much depend on the phenyl moieties attached to the side chain. This type of biological comparison could be established because of the versatility of the synthetic strategy based on the MCR tool. On the other hand, the family of

• structural characteristics of both compounds are the presence of a phenyl moiety as R1 and a t-Bu group at the terminal amide. Thus, using the same synthetic strategy as shown in Scheme 5, Dávola et al. [23] synthetized a family of new Ugi reaction-derived androstanic azasteroids with a much more diverse