Comparative study of thermally activated delayed fluorescent properties of donor–acceptor and donor–acceptor–donor architectures based on phenoxazine and dibenzo[a,j]phenazine

• Saika Izumi,
• Prasannamani Govindharaj,
• Anna Drewniak,
• Paola Zimmermann Crocomo,
• Satoshi Minakata,
• Leonardo Evaristo de Sousa,
• Piotr de Silva,
• Przemyslaw Data and
• Youhei Takeda

Beilstein J. Org. Chem. 2022, 18, 459–468, doi:10.3762/bjoc.18.48

• asymmetric D–A structure. Herein, we report the synthesis of a new asymmetric D–A compound 1 (Figure 1) as a TADF emitter and its detailed physical properties. Moreover, the developed emitter’s performance was evaluated in an OLED device. To clarify the influence of the donor number and structural symmetry

• the designed D–A molecule 1, an asymmetric dibenzophenazine electrophile was required. Recently, we have established a synthetic method for such a compound, i.e., 3-trifluoromethanesulfonyldibenzo[a,j]phenazine (DBPHZ-OTf in Scheme 1) to prepare linear-type A–D–A–D compounds [18]. Starting from the

The asymmetric Henry reaction as synthetic tool for the preparation of the drugs linezolid and rivaroxaban

• Martin Vrbický,
• Karel Macek,
• Jaroslav Pochobradský,
• Jan Svoboda,
• Miloš Sedlák and
• Pavel Drabina

Beilstein J. Org. Chem. 2022, 18, 438–445, doi:10.3762/bjoc.18.46

• antibiotic linezolid (1) and the anticoagulant rivaroxaban (2) – belong among modern pharmaceutics, which contain an oxazolidine-2-one moiety bearing a stereogenic center. The chirality of these drugs is a fundamental attribute for their biological activity. Herein, one of the efficient asymmetric syntheses

• of these drugs was studied in detail. Highly enantioselective catalysts were tested in the key step of the synthetic procedure, i.e., the asymmetric Henry reaction, under different reaction conditions, using several starting aldehydes. The corresponding nitroaldols as chiral intermediates in the

• syntheses of these drugs were obtained in high yields and enantiomeric excesses of up to 91% ee. Keywords: asymmetric Henry reaction; enantioselective catalysis; linezolid; oxazolidine-2-one derivatives; rivaroxaban; Introduction Oxazolidine-2-one derivatives represent an important branch of

Tetraphenylethylene-embedded pillar[5]arene-based orthogonal self-assembly for efficient photocatalysis in water

• Zhihang Bai,
• Krishnasamy Velmurugan,
• Xueqi Tian,
• Minzan Zuo,
• Kaiya Wang and
• Xiao-Yu Hu

Beilstein J. Org. Chem. 2022, 18, 429–437, doi:10.3762/bjoc.18.45

• a photocatalytic dehalogenation reaction, i.e., debromination of 2-bromo-1-phenylethanone derivatives with high yields and short reaction time in an aqueous solution. Based on the above results, the fabricated AIE-emissive FRET system with chiral guest can be further utilized for asymmetric

Menadione: a platform and a target to valuable compounds synthesis

• Acácio S. de Souza,
• Ruan Carlos B. Ribeiro,
• Dora C. S. Costa,
• Fernanda P. Pauli,
• David R. Pinho,
• Matheus G. de Moraes,
• Fernando de C. da Silva,
• Luana da S. M. Forezi and
• Vitor F. Ferreira

Beilstein J. Org. Chem. 2022, 18, 381–419, doi:10.3762/bjoc.18.43

• from cinchonine PTC 44 as catalyst. Despite of good yields, the method did not demonstrate good enantioselectivity results [104]. Berkessel and co-workers, in turn, described the use of asymmetric Weitz–Scheffer-type epoxidation of menadione (10), mediated by cinchona alkaloid PTC 45, showing high

• of asymmetric compound 50 catalyzed by a chiral oxazaborolidinium cation (49) [107]. This type of catalyst has been used in several Diels–Alder reactions proving to be an excellent choice for highly enantioselective reactions [108]. For instance, the reaction of menadione (10) with 2

A Se···O bonding catalysis approach to the synthesis of calix[4]pyrroles

• Qingzhe Tong,
• Zhiguo Zhao and
• Yao Wang

Beilstein J. Org. Chem. 2022, 18, 325–330, doi:10.3762/bjoc.18.36

• investigation on using an asymmetric ketone such as pentan-2-one as a reactant showed that the reaction gave an inseparable mixture of diastereomers. Meanwhile, upon using benzaldehyde as a reactant, the reaction system was complex and there was no major product. Proposed activation mode The chalcogen bonding

Unexpected chiral vicinal tetrasubstituted diamines via borylcopper-mediated homocoupling of isatin imines

• Marco Manenti,
• Leonardo Lo Presti,
• Giorgio Molteni and
• Alessandra Silvani

Beilstein J. Org. Chem. 2022, 18, 303–308, doi:10.3762/bjoc.18.34

• Marco Manenti Leonardo Lo Presti Giorgio Molteni Alessandra Silvani Dipartimento di Chimica, Università degli Studi di Milano, Via Golgi 19, Milano, 20133, Italy 10.3762/bjoc.18.34 Abstract Addressing the asymmetric synthesis of oxindole-based α-aminoboronic acids, instead of the expected

• oxindole-based α-aminoboronates. The asymmetric synthesis of diverse α-aminoboronic acids by diastereoselective Cu(I)-catalyzed borylation of N-tert-butanesulfinyl aldimines was described by Ellman and co-workers for the first time in 2008 [15] and next further developed with a more stable Cu(II) catalyst

• . Interestingly, the molecule does not bear any pseudo-mirror plane, that is, the observed conformer is asymmetric (C1) in itself, regardless the configuration of the two sulfinamide substituents. This peculiarity is likely due to the hindered rotation across the newly formed C–C bond, joining the two oxindole

Regioselectivity of the S_EAr-based cyclizations and S_EAr-terminated annulations of 3,5-unsubstituted, 4-substituted indoles

• Jonali Das and
• Sajal Kumar Das

Beilstein J. Org. Chem. 2022, 18, 293–302, doi:10.3762/bjoc.18.33

• [Pd(C3H5)Cl]2 and ligand L1 (Scheme 2) [11]. The reaction, that could also be considered as Friedel–Crafts type, intramolecular allylic alkylation, delivered nine-membered ring bearing 3,4-fused indoles 2 in moderate to good yields. In the asymmetric version of the reaction catalyzed by [Ir(cod)Cl]2

• 2021, Deng et al. showcased an unprecedented iridium-catalyzed asymmetric [4 + 3] cycloaddition of racemic 4-indolyl allylic alcohols 22 with α-imino esters 23 as azomethine ylide precursors to afford azepino[3,4,5-cd]indoles 24 in good yields and with complete regioselectivity and generally excellent

• cyclization leading to the formation of polycyclic azepino[5,4,3-cd]indoles. Synthesis of azepino[3,4,5-cd]indoles via iridium-catalyzed asymmetric [4 + 3] cycloaddition of racemic 4-indolyl allylic alcohols with azomethine ylides. Aldimine condensation/1,6-hydride transfer/Mannich-type cyclization cascade of

Recent developments and trends in the iron- and cobalt-catalyzed Sonogashira reactions

• Surendran Amrutha,
• Sankaran Radhika and
• Gopinathan Anilkumar

Beilstein J. Org. Chem. 2022, 18, 262–285, doi:10.3762/bjoc.18.31

• products. Both, asymmetric and symmetric alkynes were synthesized by this one pot method without the use of any organic solvent. For a better yield of the coupled alkyne product, Zn powder was used as a reductant. Lower yields were obtained by the use of ortho-substituted arylynols as the substrate due to

New advances in asymmetric organocatalysis

• Radovan Šebesta

Beilstein J. Org. Chem. 2022, 18, 240–242, doi:10.3762/bjoc.18.28

• Radovan Sebesta Department of Organic Chemistry, Faculty of Natural Sciences, Comenius University in Bratislava, Mlynská dolina, Ilkovičova 6, 842 15 Bratislava, Slovakia 10.3762/bjoc.18.28 Keywords: asymmetric organocatalysis; covalent activation; noncovalent activation; Asymmetric catalysis is

• combination of activation modes in bifunctional or multifunctional catalysis. Important is also a “green” aspect of organocatalysis as well as its fruitful overlap with many sustainability ideas [15]. In 2012, there has been a thematic issue of the Beilstein Journal of Organic Chemistry devoted to asymmetric

• organocatalysis edited by one of the pioneers Benjamin List. After another decade, this thematic issue likes to survey new advances in this field. Three review articles and nine research papers showcase the diversity and breadth into which asymmetric organocatalysis has grown since then. The suitability of

Organocatalytic asymmetric nitroso aldol reaction of α-substituted malonamates

• Ekta Gupta,
• Narendra Kumar Vaishanv,
• Sandeep Kumar,
• Raja Krishnan Purshottam,
• Ruchir Kant and
• Kishor Mohanan

Beilstein J. Org. Chem. 2022, 18, 217–224, doi:10.3762/bjoc.18.25

• noteworthy and widely explored transformations of nitrosoarenes include nitroso ene reactions [9][10][11], Diels–Alder cycloadditions [12][13][14][15][16][17][18], and nitroso aldol reactions [19][20][21][22][23]. Among the various applications of nitrosoarenes, the asymmetric nitroso aldol reaction to

• reported a squaramide-catalyzed asymmetric nitroso aldol reaction of cyclic β-ketoesters and malonamate [61]. Inspired by this, we decided to investigate the use of malonamate in the asymmetric nitroso aldol reaction using thiourea catalysis. Herein, we report a novel nitroso aldol reaction of malonamates

• takes place to afford the nitroso aldol product. Conclusion In summary, an efficient organocatalytic asymmetric nitroso aldol reaction of α-methylmalonamate has been reported. The reaction utilizes the well-known Takemoto catalyst, and this protocol demonstrates for the first time the use of malonamate

Multi-faceted reactivity of N-fluorobenzenesulfonimide (NFSI) under mechanochemical conditions: fluorination, fluorodemethylation, sulfonylation, and amidation reactions

• José G. Hernández,
• Karen J. Ardila-Fierro,
• Dajana Barišić and
• Hervé Geneste

Beilstein J. Org. Chem. 2022, 18, 182–189, doi:10.3762/bjoc.18.20

• reagent [9][10][11], and phenylsulfonyl group transfer reagent [12][13]. In the field of mechanochemistry, the usefulness of N-fluorobenzenesulfonimide has been exemplified in the asymmetric fluorination of β-keto esters (Scheme 1a) [14], and in diastereoselective fluorinations (Scheme 1b) [15], which

Synthesis and late stage modifications of Cyl derivatives

• Phil Servatius and
• Uli Kazmaier

Beilstein J. Org. Chem. 2022, 18, 174–181, doi:10.3762/bjoc.18.19

• decided to take advantage of an asymmetric chelate enolate Claisen rearrangement, which should allow the stereoselective generation of the unusual amino acid, depending on the configuration of the chiral allylic alcohol used [41][42]. If a peptide Claisen rearrangement [43][44][45] is carried out with a

• degree of variability for the generation of small libraries, in our case of Cyl-1 derivatives. Chiral allylic alcohols are easily accessible, either via kinetic resolution of racemic alcohols [46][47], asymmetric catalysis [48], or from chiral pool materials, such as threitol 1 [49]. Using the last

Asymmetric organocatalytic Michael addition of cyclopentane-1,2-dione to alkylidene oxindole

• Estelle Silm,
• Ivar Järving and
• Tõnis Kanger

Beilstein J. Org. Chem. 2022, 18, 167–173, doi:10.3762/bjoc.18.18

• Estelle Silm Ivar Jarving Tonis Kanger Department of Chemistry and Biotechnology, Tallinn University of Technology, Akadeemia tee 15, 12618 Tallinn, Estonia 10.3762/bjoc.18.18 Abstract An asymmetric Michael reaction between cyclopentane-1,2-dione and alkylidene oxindole was studied in the

• malonates [25]. Herein, we report the results of an asymmetric organocatalytic Michael addition of CPD to alkylidene oxindoles. Results and Discussion Chiral multifunctional thioureas [26][27] and squaramides [28] are extensively used as catalysts in asymmetric Michael additions. We believed that a

• cyclised product was detected. Conclusion In summary, we have developed a new asymmetric organocatalytic Michael addition of cyclopentane-1,2-dione to alkylidene oxindoles catalysed by bifunctional squaramide which leads to products in high enantioselectivities and moderate diastereoselectivities. The

Regioselective synthesis of methyl 5-(N-Boc-cycloaminyl)-1,2-oxazole-4-carboxylates as new amino acid-like building blocks

• Jolita Bruzgulienė,
• Greta Račkauskienė,
• Aurimas Bieliauskas,
• Vaida Milišiūnaitė,
• Miglė Dagilienė,
• Gita Matulevičiūtė,
• Vytas Martynaitis,
• Sonata Krikštolaitytė,
• Frank A. Sløk and
• Algirdas Šačkus

Beilstein J. Org. Chem. 2022, 18, 102–109, doi:10.3762/bjoc.18.11

• asymmetric unit of the crystal of 6b consists of two (2S)-2-[4-(methoxycarbonyl)-1,2-oxazol-5-yl]piperidin-1-ium cations and two 2,2,2-trifluoroacetate anions (2C10H15N2O3+·2C2F3O2−) (Figure 5; Table 1, Supporting Information File 1 in Tables S1–S3). The substituted piperidinium moieties are in chair

• 1.44 ppm. ORTEP diagram of the asymmetric unit consisting of two cations 6b(A) and 6b(B) and triflate anions. Conversion of cyclic amino acids to 1,2-oxazole derivatives. Plausible mechanisms for the formation of 1,2-oxazoles 4a–h and VII from β-enamino ketoesters 3a–h with hydroxylamine. Synthesis of

• compound 15N-1,2-oxazole 5. The coupling constants of JHN and JCN from 15N2 are indicated by arrows. Synthesis of 2-[4-(methoxycarbonyl)-1,2-oxazol-5-yl]cycloaminyl-1-ium trifluoroacetates 6a,b. Bond lengths and angles of 1,2-oxazole fragments in an asymmetric unit of 6b. Supporting Information Supporting

Efficient synthesis of ethyl 2-(oxazolin-2-yl)alkanoates via ethoxycarbonylketene-induced electrophilic ring expansion of aziridines

• Yelong Lei and
• Jiaxi Xu

Beilstein J. Org. Chem. 2022, 18, 70–76, doi:10.3762/bjoc.18.6

• groups in symmetric and asymmetric ligands widely applied in various organic transformations [7]. Especially, bisoxazolines are a kind of widely applied chiral ligands in diverse transition metal-participating asymmetric catalysis [8][9][10]. Several methods have been developed for the efficient

Bifunctional thiourea-catalyzed asymmetric [3 + 2] annulation reactions of 2-isothiocyanato-1-indanones with barbiturate-based olefins

• Jiang-Song Zhai and
• Da-Ming Du

Beilstein J. Org. Chem. 2022, 18, 25–36, doi:10.3762/bjoc.18.3

• Jiang-Song Zhai Da-Ming Du School of Chemistry and Chemical Engineering, Beijing Institute of Technology, No.5 Zhongguancun South Street, Beijing 100081, People’s Republic of China 10.3762/bjoc.18.3 Abstract Bifunctional thiourea-catalyzed asymmetric [3 + 2] annulation reactions of 2

• through a gram-scale synthesis, one-pot three-component reactions and further transformation experiments of the products. Keywords: asymmetric catalysis; cyclization reaction; Michael addition; one-pot three-component reaction; spirobarbiturates; Introduction Indane scaffolds exist in various

• construction of bispirobarbiturates [30][31]. In 2019, for example, An and co-workers reported an asymmetric Michael/Mannich [3 + 2] cycloaddition reaction between N-(2,2,2-trifluoroethyl)isatin ketimines and barbiturate-based olefins (Scheme 1a) [32]. Based on the current knowledge, the construction of

Stepwise PEG synthesis featuring deprotection and coupling in one pot

• Logan Mikesell,
• Dhananjani N. A. M. Eriyagama,
• Yipeng Yin,
• Bao-Yuan Lu and
• Shiyue Fang

Beilstein J. Org. Chem. 2021, 17, 2976–2982, doi:10.3762/bjoc.17.207

• product, and therefore, excess monomer can be used to drive the PEG elongation reactions to completion because the excess monomer can be easily removed from the product. However, for the synthesis of PEGs longer than (PEG)60 or asymmetric PEGs, other routes such as that in Scheme 5 using two orthogonal

• protecting groups would be preferred. Such routes can double the length of the PEG in three easy steps and the PEG product is asymmetric. It is noted that the use of base-labile protecting groups or linkers in organic synthesis involving carrying out reactions under less basic reactions and removing the

• compounds 4 and 1. Synthesis of monomer 2. PEG synthesis using the one-pot PEG elongation approach. A proposed route for the synthesis of long and asymmetric PEGs using a base-labile protecting group. Supporting Information Supporting Information File 266: Experimental details, images of TLC, and images of

Iron-catalyzed domino coupling reactions of π-systems

• Austin Pounder and
• William Tam

Beilstein J. Org. Chem. 2021, 17, 2848–2893, doi:10.3762/bjoc.17.196

• of both electron-donating and withdrawing groups on all three components of the reaction affording products in good yield; however, the reaction produced geometric isomers, consistently favoring the E isomer. The authors applied their methodology towards an asymmetric variant using a chiral

• diphosphine ligand. Preliminary results demonstrated the chiral iron species moderately controlled the enantioselectivity of the aryl Grignard cross-coupling. This work provided a proof-of-concept towards the use of vinylcyclopropanes as useful 1,5-synthons in asymmetric Fe-catalyzed cross-coupling reactions

• asymmetric carboazidation of styrene derivatives 115 (Scheme 33) [135]. The authors propose the enantioselectivity originates from the diastereoisomeric azido group transfer from the Fe(III) center to the benzylic radical. Not only did the described methodology produce enantiopure products in up to 90% ee

Host–guest interaction and properties of cucurbit[8]uril with chloramphenicol

• Lin Zhang,
• Jun Zheng,
• Guangyan Luo,
• Xiaoyue Li,
• Yunqian Zhang,
• Zhu Tao and
• Qianjun Zhang

Beilstein J. Org. Chem. 2021, 17, 2832–2839, doi:10.3762/bjoc.17.194

• asymmetric CPE@Q[8] structure, including one Q[8] and one CPE molecule and the entire CPE molecule enters the Q[8] cavity. Therefore, Q[8] and CPE form a 1:1 host–guest inclusion complex (CPE@Q[8]). Figure 2B shows the O20 atom of the CPE molecule and the port oxygen atom (O5) of Q[8] interact through the

• peaks of the O–H bonds were observed at 1106 and 1066 cm−1. The nitro-symmetric tensile vibration peak observed at 1503 cm−1 and the nitro-asymmetric tensile vibration peak at 1320 cm−1 disappeared in the spectrum (d). At the same time, the fingerprint region peak of the benzene ring observed from 500

Highly stereocontrolled total synthesis of racemic codonopsinol B through isoxazolidine-4,5-diol vinylation

• Lukáš Ďurina,
• Anna Ďurinová,
• František Trejtnar,
• Ľuboš Janotka,
• Lucia Messingerová,
• Jana Doháňošová,
• Ján Moncol and
• Róbert Fischer

Beilstein J. Org. Chem. 2021, 17, 2781–2786, doi:10.3762/bjoc.17.188

• the proline catalysis are of higher purity (after purification by silica gel column chromatography), than those synthesized by other methods [16]. Definitely, the effective asymmetric organocatalytic conjugate additions of hydroxylamines to enals using various catalysts provide access to

Recent advances in the asymmetric phosphoric acid-catalyzed synthesis of axially chiral compounds

• Alemayehu Gashaw Woldegiorgis and
• Xufeng Lin

Beilstein J. Org. Chem. 2021, 17, 2729–2764, doi:10.3762/bjoc.17.185

• active compounds in medicinal chemistry and as chiral ligands in asymmetric catalysis. Chiral phosphoric acids are recognized as efficient organocatalysts for a variety of enantioselective transformations. In this review, we summarize the recent development of chiral phosphoric acid-catalyzed synthesis

• only for pharmaceutical and fine chemical industries, but also for fragrance, flavor, agrochemical, and food industries [4]. Consequently, the importance of axially chiral compounds has been widely recognized in both academic and industrial chemical societies [5]. Therefore, asymmetric synthesis of

• acids are widely used in stereoselective oxidative/cross-coupling of two aryl counterparts, asymmetric control of aromatic ring formation, atroposelective functionalization of biaryl compounds, and so on [17][29][30]. In this context, Akiyama (2004) described that chiral phosphoric acids (CPAs) have

The ethoxycarbonyl group as both activating and protective group in N-acyl-Pictet–Spengler reactions using methoxystyrenes. A short approach to racemic 1-benzyltetrahydroisoquinoline alkaloids

• Marco Keller,
• Karl Sauvageot-Witzku,
• Franz Geisslinger,
• Nicole Urban,
• Michael Schaefer,
• Karin Bartel and
• Franz Bracher

Beilstein J. Org. Chem. 2021, 17, 2716–2725, doi:10.3762/bjoc.17.183

• enantiomerically pure alkaloids, as numerous methods for separation of enantiomers are well known in this field [52][53][54][55]. Further, this protocol might be extended to an asymmetric N-acyl-Pictet–Spengler condensation by using homochiral carbamates, as demonstrated by Comins [18], or by using

Synthetic strategies toward 1,3-oxathiolane nucleoside analogues

• Umesh P. Aher,
• Dhananjai Srivastava,
• Girij P. Singh and
• Jayashree B. S

Beilstein J. Org. Chem. 2021, 17, 2680–2715, doi:10.3762/bjoc.17.182

• to treat HIV infection [58] as well as human chronic hepatitis B [59]. Using asymmetric synthesis or resolution with appropriate enzymes to prepare these enantiopure 1,3-oxathiolanes has gained extensive attention due to the good stereoselectivity, high efficiency, mild reaction conditions, and eco

• nuclear Overhauser effect (NOE) NMR spectroscopy are useful tools to monitor and control the chirality when utilizing a modified 1,3-oxathiolane intermediate 65 obtained via enzyme-catalyzed selective hydrolysis. Hu et al. [61] established a green catalyst, STS, for the asymmetric synthesis of lamivudine

• nucleoside 1a in a protocol by Vorbrüggen et al. In turn, using STS, this valuable asymmetric synthesis provided the intermediate 65, which led to lamivudine (1). Recently, Chen at al. [62] reported the isolation of the strain Klebsiella oxytoca from soil by a target-oriented process, and it was utilized as

Ligand-dependent stereoselective Suzuki–Miyaura cross-coupling reactions of β-enamido triflates

• Tomáš Chvojka,
• Athanasios Markos,
• Svatava Voltrová,
• Radek Pohl and
• Petr Beier

Beilstein J. Org. Chem. 2021, 17, 2657–2662, doi:10.3762/bjoc.17.179

• [1][2]. Their multifacial reactivity has been explored in asymmetric alkylations [3], hydroalkynylations [4], trifluoromethylcyanations [5], heterocycle synthesis [6], asymmetric acylations [7], hydroborations [8], hydrogenations [9], etc. They are also important pharmacophores, which display a range

Electrocatalytic C(sp³)–H/C(sp)–H cross-coupling in continuous flow through TEMPO/copper relay catalysis

• Bin Guo and
• Hai-Chao Xu

Beilstein J. Org. Chem. 2021, 17, 2650–2656, doi:10.3762/bjoc.17.178

• electrochemistry is an ideal tool for promoting dehydrogenative cross-coupling reactions as no external chemical oxidants are needed [11][12][13][14][15][16][17][18][19]. In this context, Mei and co-workers have reported an elegant TEMPO/[L*Cu] co-catalyzed asymmetric electrochemical dehydrogenative cross-coupling