Recent advances in organocatalytic asymmetric aza-Michael reactions of amines and amides

• Pratibha Sharma,
• Raakhi Gupta and
• Raj K. Bansal

Beilstein J. Org. Chem. 2021, 17, 2585–2610, doi:10.3762/bjoc.17.173

• as an important synthetic strategy for the preparation of a large variety of β-amino carbonyl and similar motifs which are present in many bioactive natural products [8][9], antibiotics [10][11][12] and chiral auxiliaries [13][14][15]. However, the reaction of many nitrogen-nucleophiles, such as

• additions of these heteroarenes with crotonaldehyde yielded the adducts in moderate to good enantioselectivity under dual catalysis of chiral amines (Scheme 5) [69]. Conclusion The asymmetric aza-Michael reaction being a useful synthetic strategy for constructing C–N bonds to make a variety of nitrogen

α-Ketol and α-iminol rearrangements in synthetic organic and biosynthetic reactions

• Scott Benz and
• Andrew S. Murkin

Beilstein J. Org. Chem. 2021, 17, 2570–2584, doi:10.3762/bjoc.17.172

• from the above work from the Gademann group, Kalmode et al. incorporated the same synthetic strategy into their total synthesis of racemic periconianone A [12]. Interestingly, these authors not only tested the natural product for neural anti-inflammatory activity but also the two immediate synthetic

Exfoliated black phosphorous-mediated CuAAC chemistry for organic and macromolecular synthesis under white LED and near-IR irradiation

• Azra Kocaarslan,
• Zafer Eroglu,
• Önder Metin and
• Yusuf Yagci

Beilstein J. Org. Chem. 2021, 17, 2477–2487, doi:10.3762/bjoc.17.164

• . In this work, we report a new synthetic strategy to the photochemical reduction of CuII to CuI for the CuAAC reaction using BPNs as the photo-initiator under NIR light. Results and Discussion The detailed preparation and characterization of the initial BP crystals and BPNs were previously reported

Efficient synthesis of polyfunctionalized carbazoles and pyrrolo[3,4-c]carbazoles via domino Diels–Alder reaction

• Ren-Jie Fang,
• Chen Yan,
• Jing Sun,
• Ying Han and
• Chao-Guo Yan

Beilstein J. Org. Chem. 2021, 17, 2425–2432, doi:10.3762/bjoc.17.159

• attractive strategy for the synthesis of carbazole derivatives [28][29][30][31][32][33][34][35][36][37][38][39][40]. In recent years, by using the one-pot domino synthetic strategy of in situ-generated 2-vinyl- or 3-vinylindolines and sequential Diels–Alder reaction with activated dienophiles, we have

A novel methodology for the efficient synthesis of 3-monohalooxindoles by acidolysis of 3-phosphate-substituted oxindoles with haloid acids

• Li Liu,
• Yue Li,
• Tiao Huang,
• Dulin Kong and
• Mingshu Wu

Beilstein J. Org. Chem. 2021, 17, 2321–2328, doi:10.3762/bjoc.17.150

• University, Haikou 571199, Hainan Province, P. R. China 10.3762/bjoc.17.150 Abstract A novel method for the synthesis of 3-monohalooxindoles by acidolysis of isatin-derived 3-phosphate-substituted oxindoles with haloid acids was developed. This synthetic strategy involved the preparation of 3-phosphate

Chemical syntheses and salient features of azulene-containing homo- and copolymers

• Vijayendra S. Shetti

Beilstein J. Org. Chem. 2021, 17, 2164–2185, doi:10.3762/bjoc.17.139

• -azulene) units capable of absorbing in the near IR region (1.0 to 2.5 μm). Their synthetic strategy involved employing 1,3-dibromo-[2-(3-dodecylthien-2-yl)]azulene (46) as a key precursor and Suzuki and Stille cross-coupling reactions as polymerization tools. The polymer 50 was synthesized from the 1,3

Recent advances in the syntheses of anthracene derivatives

• Giovanni S. Baviera and
• Paulo M. Donate

Beilstein J. Org. Chem. 2021, 17, 2028–2050, doi:10.3762/bjoc.17.131

• by treatment with PCC/Celite in dichloromethane (DCM). Finally, treatment with a catalytic amount of CF3SO3H provided the corresponding anthracenes 30a–c in good yields (57–75%) [40]. Metal-catalyzed C–H bond activation In 2016, Hong’s group developed a synthetic strategy to generate substituted

Sustainable manganese catalysis for late-stage C–H functionalization of bioactive structural motifs

• Jongwoo Son

Beilstein J. Org. Chem. 2021, 17, 1733–1751, doi:10.3762/bjoc.17.122

• powerful synthetic strategy for accessing advanced agrochemicals, bioimaging materials, and drug candidates, among other complex molecules. While traditional late-stage diversification relies on the use of precious transition metals, the utilization of 3d transition metals is an emerging approach in

• azobenzenes was unveiled [1], manganese catalysts have exhibited a significant capacity for powerful C–H functionalization, and they have therefore been actively utilized in the area of sustainable organic syntheses [2][3][4][5][6]. Catalytic late-stage C–H functionalization, a highly efficient synthetic

• strategy, is regarded as a crucial tactic in the area of natural products, drug discovery, and medicinal chemistry [7][8][9][10][11][12] as it confers an invaluable synthetic opportunity for the facile diversification of biologically active complex molecules at the late stage. In recent years, much effort

Chemical approaches to discover the full potential of peptide nucleic acids in biomedical applications

• Nikita Brodyagin,
• Martins Katkevics,
• Venubabu Kotikam,
• Christopher A. Ryan and
• Eriks Rozners

Beilstein J. Org. Chem. 2021, 17, 1641–1688, doi:10.3762/bjoc.17.116

Synthesis of 1-indolyl-3,5,8-substituted γ-carbolines: one-pot solvent-free protocol and biological evaluation

• Premansh Dudhe,
• Mena Asha Krishnan,
• Kratika Yadav,
• Diptendu Roy,
• Krishnan Venkatasubbaiah,
• Biswarup Pathak and
• Venkatesh Chelvam

Beilstein J. Org. Chem. 2021, 17, 1453–1463, doi:10.3762/bjoc.17.101

• cell nucleus. The synthetic strategy of present work in comparison with previous reports. Series of synthesized 1-indolyl-3,5,8-substituted γ-carboline 3aa–ac, 3ba-ea and 1-indolyl-1,2-dihydro-3,5-substituted γ-carboline 3ga derivatives. Plausible mechanism for the formation of 1,2-dihydro-γ-carboline

Design, synthesis and photophysical properties of novel star-shaped truxene-based heterocycles utilizing ring-closing metathesis, Clauson–Kaas, Van Leusen and Ullmann-type reactions as key tools

• Shakeel Alvi and
• Rashid Ali

Beilstein J. Org. Chem. 2021, 17, 1374–1384, doi:10.3762/bjoc.17.96

• metathesis, Ullmann-type coupling, Clauson–Kaas, and Van Leusen reactions as crucial transformations. Synthetic Strategy Basically, our endeavor toward the synthesis of truxene-based systems has been rooted in the development of new synthetic methodologies to assemble diverse polycyclic as well as

• -containing five-membered aromatic pyrrole scaffold will continue to play a significant role in the development of novel anionic receptors [33][34]. Therefore, as outlined in Scheme 2, our synthetic strategy towards the construction of the target pyrrole-based truxene derivative 6 initiated with the acid

N-tert-Butanesulfinyl imines in the asymmetric synthesis of nitrogen-containing heterocycles

• Joseane A. Mendes,
• Paulo R. R. Costa,
• Miguel Yus,
• Francisco Foubelo and
• Camilla D. Buarque

Beilstein J. Org. Chem. 2021, 17, 1096–1140, doi:10.3762/bjoc.17.86

• high yields of 95% and 94%, respectively [132] (Scheme 42). Pinto and co-workers reported recently the enantioselective synthesis of natural alkaloids (−)-cermizine B 171 and (+)-serratezomine E 172. A key step of the synthetic strategy is the allylation with allylmagnesium bromide of N-tert

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

• -alkenyloxindole 43 were considered to be the building blocks united in ethanol as solvent (Scheme 15). The notable highlights of the described methodology are diastereoselective C–C and C–N bond formation, high yields, non-toxic product, and cost-effectiveness along with a greener approach. The synthetic strategy

Total synthesis of pyrrolo[2,3-c]quinoline alkaloid: trigonoine B

• Takashi Nishiyama,
• Erina Hamada,
• Daishi Ishii,
• Yuuto Kihara,
• Nanase Choshi,
• Natsumi Nakanishi,
• Mari Murakami,
• Kimiko Taninaka,
• Noriyuki Hatae and
• Tominari Choshi

Beilstein J. Org. Chem. 2021, 17, 730–736, doi:10.3762/bjoc.17.62

• . Consequently, we decided to develop a new synthetic strategy for the preparation of trigonoine B (1). Carbodiimides are valuable synthetic intermediates that can be obtained by an aza-Wittig reaction of isocyanates with iminophosphoranes or by dehydration of urea [26]. Molina et al. previously reported the

Synthetic strategies of phosphonodepsipeptides

• Jiaxi Xu

Beilstein J. Org. Chem. 2021, 17, 461–484, doi:10.3762/bjoc.17.41

• species than the corresponding phosphonochloridates in the esterification, this synthetic strategy had not been applied by others. There is only one example reported till now possibly due to the inconvenient preparation of the phosphonochloridites. Synthesis of phosphonodepsipeptides via the addition of

• -hydroxyisovaleric acid-derived spirophosphoranes as the phosphorus reagents [57]. By using a similar strategy, linker-linked bisphosphonodepsidipeptides were synthesized [10]. The current method is also an interesting synthetic strategy of phosphonodepsipeptides. It can realize an asymmetric synthesis of

• synthetic methods, the multicomponent Mannich-type condensation strategy shows a high efficiency, convergent feature, and product diversity. It can be expected that the convergent multicomponent condensation synthetic strategy will show wide applications in the preparation of biologically active

¹⁹F NMR as a tool in chemical biology

• Diana Gimenez,
• Aoife Phelan,
• Cormac D. Murphy and
• Steven L. Cobb

Beilstein J. Org. Chem. 2021, 17, 293–318, doi:10.3762/bjoc.17.28

• , Otting and co-workers have recently developed a synthetic strategy, based on a continuous exchange cell-free system (CECF), in which a key chitin-binding mutant of release factor RF1 can be removed under conditions that maintain the full activity of the S30 extract, thereby minimizing the incidence of

Synthesis, crystal structures and properties of carbazole-based [6]helicenes fused with an azine ring

• Daria I. Tonkoglazova,
• Anna V. Gulevskaya,
• Konstantin A. Chistyakov and
• Olga I. Askalepova

Beilstein J. Org. Chem. 2021, 17, 11–21, doi:10.3762/bjoc.17.2

• % ii) SPINOL-derived phosphoric acid, Amberlite CG50, CH2Cl2, −7 °C, 72 h, 74%; iii) chloranil, diphenyl phosphate, CHCl3, 50 °C, 5 h, 76%. Synthetic strategy for the carbazole-based [6]helicenes fused with an azine ring. Sonogashira coupling of compound 4b with phenylacetylene. i) Pd(PPh3)2Cl2, CuI

Naphthalonitriles featuring efficient emission in solution and in the solid state

• Sidharth Thulaseedharan Nair Sailaja,
• Iván Maisuls,
• Jutta Kösters,
• Alexander Hepp,
• Andreas Faust,
• Jens Voskuhl and
• Cristian A. Strassert

Beilstein J. Org. Chem. 2020, 16, 2960–2970, doi:10.3762/bjoc.16.246

• decrease in the dielectric constant. In summary, our straightforward synthetic strategy enables the realization of molecules which can go from deep blue to red emission and highly luminescent materials in solution and in the solid state, which are potentially interesting for optoelectronic and bioimaging

Recent developments in enantioselective photocatalysis

• Callum Prentice,
• James Morrisson,
• Andrew D. Smith and
• Eli Zysman-Colman

Beilstein J. Org. Chem. 2020, 16, 2363–2441, doi:10.3762/bjoc.16.197

• transformative synthetic strategy, including in enantioselective synthesis. From the pioneering work by MacMillan [1] and Bach [2], enantioselective photocatalysis has grown into a well-established field of its own. A large proportion of photocatalysis focuses on photoredox catalysis, which involves single

The B & B approach: Ball-milling conjugation of dextran with phenylboronic acid (PBA)-functionalized BODIPY

• Patrizia Andreozzi,
• Lorenza Tamberi,
• Elisamaria Tasca,
• Gina Elena Giacomazzo,
• Marta Martinez,
• Mirko Severi,
• Marco Marradi,
• Stefano Cicchi,
• Sergio Moya,
• Giacomo Biagiotti and
• Barbara Richichi

Beilstein J. Org. Chem. 2020, 16, 2272–2281, doi:10.3762/bjoc.16.188

• ), by following a straightforward synthetic strategy recently reported by some of us [26]. Then, in order to assess the efficacy of the solid-state milling approach in the formation of boronate esters between the PBA moiety of 1 and the vicinal diols of dextran (Dex), both mechanochemical and

• mitochondrial activity was determined by the following formula: (Absorbance of treated cells/ Absorbance of control cells) × 100 (%). Synthesis of 3,5-dichloro-4,4-difluoro-8-(4-boronophenyl)-4-bora-3a,4a-diaza-s-indacene (PBA-BODIPY, 1) PBA-BODIPY (1) was prepared following the synthetic strategy reported in

Synthetic approaches to bowl-shaped π-conjugated sumanene and its congeners

• Shakeel Alvi and
• Rashid Ali

Beilstein J. Org. Chem. 2020, 16, 2212–2259, doi:10.3762/bjoc.16.186

• /mol) transformation of 12 (syn) to 17, calculated by density functional theory (DFT) calculations. On the other hand, in 2008, Higashibayashi et al. reported the synthesis of first chiral C3-symmetric trimethylsumanene 28 starting from enantiopure norbornadiene (10) by employing a rational synthetic

• strategy via the transfer of sp3 chirality of 27 into the bowl chirality of 28 as a key conversion (Scheme 3) [17][31]. In this context, they began with the Pd-catalyzed hydrosilylation reaction using HSiCl3 at −3 °C in the presence of a chiral phosphine ligand to furnish the hydrosilylated product which

Convenient access to pyrrolidin-3-ylphosphonic acids and tetrahydro-2H-pyran-3-ylphosphonates with multiple contiguous stereocenters from nonracemic adducts of a Ni(II)-catalyzed Michael reaction

• Alexander N. Reznikov,
• Dmitry S. Nikerov,
• Anastasiya E. Sibiryakova,
• Victor B. Rybakov,
• Evgeniy V. Golovin and
• Yuri N. Klimochkin

Beilstein J. Org. Chem. 2020, 16, 2073–2079, doi:10.3762/bjoc.16.174

• University, Leninskie Gory, 1, 119991, Mosсow, Russian Federation 10.3762/bjoc.16.174 Abstract A new synthetic strategy toward nonracemic phosphoryl-substituted pyrrolidines and tetrahydropyranes with three and five contiguous stereocenters is presented. Readily available β-keto phosphonates react with

Synthesis of monophosphorylated lipid A precursors using 2-naphthylmethyl ether as a protecting group

• Jundi Xue,
• Ziyi Han,
• Gen Li,
• Khalisha A. Emmanuel,
• Cynthia L. McManus,
• Qiang Sui,
• Dongmian Ge,
• Qi Gao and
• Li Cai

Beilstein J. Org. Chem. 2020, 16, 1955–1962, doi:10.3762/bjoc.16.162

• the molecule until the final global deprotection step. Our synthetic strategy is not only efficient in regards to the yield of the various chemical transformations, but also robust in regards to the potential application of this route to the production of other lipid A analogs. Keywords: lipid A

• functionalities in target molecules for the synthesis of glycoconjugates. Based on the synthetic strategy described in this work (a common building block and Nap ether protection), we have already designed a route to MPLA, a clinically safe [30] monophosphoryl lipid A derivative with one phosphate group linked to

Et₃N/DMSO-supported one-pot synthesis of highly fluorescent β-carboline-linked benzothiophenones via sulfur insertion and estimation of the photophysical properties

• Dharmender Singh,
• Vipin Kumar and
• Virender Singh

Beilstein J. Org. Chem. 2020, 16, 1740–1753, doi:10.3762/bjoc.16.146

• incorporation of sulfur to generate multifunctional β-carboline-linked benzothiophenones in good to excellent yields. The synthetic strategy could also be extended towards the synthesis of β-carboline-linked benzothiophenes. Moreover, the afforded products emerged as promising fluorophores and displayed

Nonenzymatic synthesis of anomerically pure, mannosyl-based molecular probes for scramblase identification studies

• Giovanni Picca,
• Markus Probst,
• Simon M. Langenegger,
• Oleg Khorev,
• Peter Bütikofer,
• Anant K. Menon and
• Robert Häner

Beilstein J. Org. Chem. 2020, 16, 1732–1739, doi:10.3762/bjoc.16.145

• configuration at the anomeric position and to prove the working principle of our synthetic strategy, we used 2D NMR experiments. Coupled HSQC measurements revealed the 1JCH coupling constants of our compounds and thereby the absolute configuration at the anomeric center of the carbohydrate [40][41][42]. For MPC