Hierarchically assembled helicates as reaction platform – from stoichiometric Diels–Alder reactions to enamine catalysis

• David Van Craen,
• Jenny Begall,
• Johannes Großkurth,
• Leonard Himmel,
• Oliver Linnenberg,
• Elisabeth Isaak and
• Markus Albrecht

Beilstein J. Org. Chem. 2020, 16, 2338–2345, doi:10.3762/bjoc.16.195

• periphery of hierarchically assembled titanium(IV) helicates formed from mixtures of achiral, reactive and chiral, unreactive ligands was investigated in detail. Following the pathway of the chiral induction, the chiral ligands, solvents as well as substituents at the dienophile were carefully varied. Based

• or rigid chiral ligands. In addition, a solvent screening was performed in which solvents were used which favor the dimer. This is imminent for good enantioselectivities because the presence of a high amount of stereolabile monomer switches off the selectivity [13]. Solvent dependence Initially the

• lithium cations. Chloroform showed the best induction with 32% ee followed by dichloromethane with 25% ee, both with 50% yield (Table 1). Ligand screening In a second optimization step, the chiral ligands have been varied. An increase of stereoselectivity was achieved by using the helicates with a

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

• ][22][23]. On the other hands, further extension of these molecules leads to homochiral carbon nanotubes which can produce innovative perception in chiral sensing, chiral catalysis, separation techniques and chiral ligands for organocatalysis [24]. Additionally, control on the bowl-to-bowl inversion

Controlling the stereochemistry in 2-oxo-aldehyde-derived Ugi adducts through the cinchona alkaloid-promoted electrophilic fluorination

• Yuqing Wang,
• Gaigai Wang,
• Anatoly A. Peshkov,
• Ruwei Yao,
• Muhammad Hasan,
• Manzoor Zaman,
• Chao Liu,
• Stepan Kashtanov,
• Olga P. Pereshivko and
• Vsevolod A. Peshkov

Beilstein J. Org. Chem. 2020, 16, 1963–1973, doi:10.3762/bjoc.16.163

• stereocontrol was achieved with the aid of different Lewis acid promoters bearing chiral ligands, while the most recent and at the same time the most general procedure developed by Liu, Tan and co-workers relied on the stereoinduction by a chiral phosphoric acid (Table 1) [40]. In the standard Ugi four

Copper-catalysed alkylation of heterocyclic acceptors with organometallic reagents

• Yafei Guo and
• Syuzanna R. Harutyunyan

Beilstein J. Org. Chem. 2020, 16, 1006–1021, doi:10.3762/bjoc.16.90

• variety of methods employing the chiral ligands L9–L13 that, in combination with copper, efficiently catalysed the ACA of diethylzinc to 5,6-dihydro-2-pyranone (Scheme 8), providing access to chiral β-substituted lactones with high enantioselectivity and conversion [33][34][35][36][37]. Although the

• copper catalysts to activate both the organometallics and heterocyclic acceptors for the reaction. The development of a wide variety of chiral ligands allowed an impressive scope of heterocycles to undergo reactions with organometallics. However, the current state of the field is certainly incomplete

Pd-catalyzed asymmetric Suzuki–Miyaura coupling reactions for the synthesis of chiral biaryl compounds with a large steric substituent at the 2-position

• Yongsu Li,
• Bendu Pan,
• Xuefeng He,
• Wang Xia,
• Yaqi Zhang,
• Hao Liang,
• Chitreddy V. Subba Reddy,
• Rihui Cao and
• Liqin Qiu

Beilstein J. Org. Chem. 2020, 16, 966–973, doi:10.3762/bjoc.16.85

• from chemists because of their widespread appearance in biologically active compounds [1][2][3][4] such as vancomycin [5] and korupensamine A [6] and as useful chiral ligands in asymmetric catalysis. Different strategies with various metals and phosphine ligands had been successfully employed for the

Copper-catalyzed enantioselective conjugate reduction of α,β-unsaturated esters with chiral phenol–carbene ligands

• Shohei Mimura,
• Sho Mizushima,
• Yohei Shimizu and
• Masaya Sawamura

Beilstein J. Org. Chem. 2020, 16, 537–543, doi:10.3762/bjoc.16.50

• chiral p-tol-BINAP/copper catalyst established the excellent utility of chiral bisphosphine ligands for this type of reaction [4]. Surprisingly, however, chiral ligands based on N-heterocyclic carbenes (NHCs) [12] have not been applied to the conjugate reduction of α,β-unsaturated carbonyl compounds

• product 2i with comparable results (Table 2, entry 10, 81% yield, 79% ee). Proposed catalytic cycle Based on the experimental observations and previous knowledge of the catalysis of phenol–NHC chiral ligands [14][15][16][17][18], we propose a catalytic cycle as shown in Scheme 1. LiOt-Bu abstracts the two

Architecture and synthesis of P,N-heterocyclic phosphine ligands

• Wisdom A. Munzeiwa,
• Bernard Omondi and
• Vincent O. Nyamori

Beilstein J. Org. Chem. 2020, 16, 362–383, doi:10.3762/bjoc.16.35

• family of privileged chiral ligands in asymmetric catalysis [12]. In these compounds, the C2 axis of symmetry helps in increasing the selectivity of the formation of certain enantiomers by inhibiting other possible reaction pathways [93]. In particular, biarylphosphines and bidentate 2,2'-bis

• coordination making it ideal for syntheses of chiral ligands [118]. In the recent decades, Ugi’s amine has been one of the major interesting chiral ferrocenyl derivatives because the configuration at the α-ferrocenylmethyl position can be retained after nucleophilic substitution [115]. Drahonovsky et al. [120

Copper-catalyzed enantioselective conjugate addition of organometallic reagents to challenging Michael acceptors

• Delphine Pichon,
• Jennifer Morvan,
• Christophe Crévisy and
• Marc Mauduit

Beilstein J. Org. Chem. 2020, 16, 212–232, doi:10.3762/bjoc.16.24

• listed above can be converted into various other synthetically useful groups, such as ketones, esters, carboxylic acids, and (Weinreb) amide groups. More recently, some works were reported, which showed that through a judicious selection of chiral ligands and a fine-tuning of the reactivities of both

• , and thus opening a new field for the total synthesis of natural products. We hope that the results collected in this review will encourage chemists on one hand to continue the search for improved procedures combining simple, easily accessible chiral ligands, lower catalytic loadings, high ee values

A review of asymmetric synthetic organic electrochemistry and electrocatalysis: concepts, applications, recent developments and future directions

• Munmun Ghosh,
• Valmik S. Shinde and
• Magnus Rueping

Beilstein J. Org. Chem. 2019, 15, 2710–2746, doi:10.3762/bjoc.15.264

• corresponding bromo-cyclopropane 17 [24]. According to the authors, the passage of larger amounts of charge to facilitate product isolation might be responsible for the observed lower asymmetric yields. In 1998, Moutet’s group reported for the first time that transition metal complexes with chiral ligands can

Chiral terpene auxiliaries V: Synthesis of new chiral γ-hydroxyphosphine oxides derived from α-pinene

• Anna Kmieciak and
• Marek P. Krzemiński

Beilstein J. Org. Chem. 2019, 15, 2493–2499, doi:10.3762/bjoc.15.242

• research groups [1]. Compounds with a phosphorus atom attached to a stereogenic carbon center in acyclic and cyclic structures play an important role as chiral ligands in transition metal complexes [2]. They were applied to various catalytic asymmetric reactions [3][4], such as hydrogenations [3][4][5][6

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

• -diamine complexes are air and moisture-stable (Scheme 49). In 2011, two nickel-catalyzed protocols for the enantioselective α-fluorination of β-ketoesters were reported separately. In van Leeuwen’s reaction, SPANamine derivatives were synthesized and applied as chiral ligands in the asymmetric α

The LANCA three-component reaction to highly substituted β-ketoenamides – versatile intermediates for the synthesis of functionalized pyridine, pyrimidine, oxazole and quinoxaline derivatives

• Tilman Lechel,
• Roopender Kumar,
• Mrinal K. Bera,
• Reinhold Zimmer and
• Hans-Ulrich Reissig

Beilstein J. Org. Chem. 2019, 15, 655–678, doi:10.3762/bjoc.15.61

• chiral compounds were converted into the corresponding pyridin-4-ol derivatives and tested as chiral ligands in asymmetric catalysis [37]. Using the N-trityl-substituted proline as carboxylic acid provided the expected β-ketoenamide KE42 in low yield and as major product we isolated compound 7 in 49

Synthesis of C₃-symmetric star-shaped molecules containing α-amino acids and dipeptides via Negishi coupling as a key step

• Sambasivarao Kotha and
• Saidulu Todeti

Beilstein J. Org. Chem. 2019, 15, 371–377, doi:10.3762/bjoc.15.33

• peptide dendrimers. Keywords: amino acids; cyclotrimerization; Negishi coupling; peptide; Introduction Optically active C3-symmetric molecules are valuable synthons to design dendrimers, chiral ligands, polymers, and supramolecules [1][2][3][4]. In this regard, 1,3,5-triarylbenzene derivatives are

Some mechanistic aspects regarding the Suzuki–Miyaura reaction between selected ortho-substituted phenylboronic acids and 3,4,5-tribromo-2,6-dimethylpyridine

• Piotr Pomarański,
• Piotr Roszkowski,
• Jan K. Maurin,
• Armand Budzianowski and
• Zbigniew Czarnocki

Beilstein J. Org. Chem. 2018, 14, 2384–2393, doi:10.3762/bjoc.14.214

• essential stereochemical element of many popular, commercially available chiral catalysts [3]. Several ortho-substituted arylpyridine derivatives belong to a very important class of axially chiral compounds which have gained interest due to their role as chiral ligands in cross-coupling reactions, or being

Chiral bisoxazoline ligands designed to stabilize bimetallic complexes

• Deepankar Das,
• Rudrajit Mal,
• Nisha Mittal,
• Zhengbo Zhu,
• Thomas J. Emge and
• Daniel Seidel

Beilstein J. Org. Chem. 2018, 14, 2002–2011, doi:10.3762/bjoc.14.175

• pyridazine-bridged, and bis-nickel as well as bis-palladium pyrazole-bridged complexes were obtained. Keywords: bimetallic complexes; bisoxazolines; chiral ligands; heterocycles; Introduction Metal-centered asymmetric catalysis most commonly relies on monometallic complexes of various chiral ligands, among

Synthesis of chiral 3-substituted 3-amino-2-oxindoles through enantioselective catalytic nucleophilic additions to isatin imines

• Hélène Pellissier

Beilstein J. Org. Chem. 2018, 14, 1349–1369, doi:10.3762/bjoc.14.114

•  20. In 2016, Zhang and Yang reported an asymmetric palladium-catalyzed addition of arylboronic acids 60 to sterically hindered N-tert-butylsulfonylisatin imines 61 [80]. Among a variety of chiral ligands investigated, including different pyridine-oxazolines, oxazolines and (R)-BINAP, the chiral

Fluorocyclisation via I(I)/I(III) catalysis: a concise route to fluorinated oxazolines

• Felix Scheidt,
• Christian Thiehoff,
• Gülay Yilmaz,
• Stephanie Meyer,
• Constantin G. Daniliuc,
• Gerald Kehr and
• Ryan Gilmour

Beilstein J. Org. Chem. 2018, 14, 1021–1027, doi:10.3762/bjoc.14.88

• ranging from drug delivery through to tissue engineering [3][4]. Collectively, the importance of the 2-oxazoline scaffold for translational research, together with its strategic value in the design of chiral ligands and auxiliaries [5][6][7], has culminated in a rich and innovative arsenal of synthetic

Enantioselective dioxytosylation of styrenes using lactate-based chiral hypervalent iodine(III)

• Morifumi Fujita,
• Koki Miura and
• Takashi Sugimura

Beilstein J. Org. Chem. 2018, 14, 659–663, doi:10.3762/bjoc.14.53

• the electronic and steric properties of the aryl group and the heteroatomic ligand coordinated to the iodine atom. Optically active hypervalent iodine compounds contain chiral ligands or chiral aryl groups. Several types of optically active hypervalent iodine reagents and catalysts have been developed

Recent developments in the asymmetric Reformatsky-type reaction

• Hélène Pellissier

Beilstein J. Org. Chem. 2018, 14, 325–344, doi:10.3762/bjoc.14.21

• enantioselective (aza)-variants by using chiral substrates or chiral ligands. As illustrated in this review, the diastereoselective Reformatsky reactions of chiral substrates or auxiliaries have been applied to the total synthesis of a number of important products, such as naturally occurring bioactive products

• Reformatsky reactions [16]. The present review is divided into two parts, dealing successively with diastereoselective (aza)-Reformatsky reactions of chiral substrates or auxiliaries and catalytic enantioselective (aza)-Reformatsky reactions using chiral ligands. Review Diastereoselective Reformatsky

• reassignment of the relative stereochemistries and absolute configurations of their natural counterparts (−)-Q-1047H-A-A and (−)-Q-1047H-R-A. Catalytic enantioselective (aza)-Reformatsky reactions Reformatsky reactions In recent years, novel chiral ligands have been designed to promote catalytic

Polarization spectroscopy methods in the determination of interactions of small molecules with nucleic acids – tutorial

• Tamara Šmidlehner,
• Ivo Piantanida and
• Gennaro Pescitelli

Beilstein J. Org. Chem. 2018, 14, 84–105, doi:10.3762/bjoc.14.5

• absorption spectra for chiral ligands, ECD spectra at different concentrations can be collected, taking into account that the total absorbance of the sample is compatible with the sensitivity of the instrument. Again, aggregating ligands could form chiral aggregates with a characteristic exciton-coupled CD

Effect of uridine protecting groups on the diastereoselectivity of uridine-derived aldehyde 5’-alkynylation

• Raja Ben Othman,
• Mickaël J. Fer,
• Laurent Le Corre,
• Sandrine Calvet-Vitale and
• Christine Gravier-Pelletier

Beilstein J. Org. Chem. 2017, 13, 1533–1541, doi:10.3762/bjoc.13.153

• ][17][35][42][43][44][45][46][47]. Aside from the use of chiral ligands promoting an excellent facial discrimination of the aldehyde [34], the addition of Grignard reagents usually proceed with moderate diastereoselectivity and yield (Table 1) [12][35][43][44][45][46][48]. In the course of our program

Chromium(II)-catalyzed enantioselective arylation of ketones

• Gang Wang,
• Shutao Sun,
• Ying Mao,
• Zhiyu Xie and
• Lei Liu

Beilstein J. Org. Chem. 2016, 12, 2771–2775, doi:10.3762/bjoc.12.275

• ) was selected as the model reaction for optimization employing Kishi’s oxazoline/sulfonamides as the chiral ligands. A series of oxazoline/sulfonamide ligands (L1–L8) were tested and the results were summarized in Table 1. Four subgroups of R1 were studied (entries 1–4, Table 1) and isopropyl

Copper-catalyzed asymmetric sp³ C–H arylation of tetrahydroisoquinoline mediated by a visible light photoredox catalyst

• Pierre Querard,
• Inna Perepichka,
• Eli Zysman-Colman and
• Chao-Jun Li

Beilstein J. Org. Chem. 2016, 12, 2636–2643, doi:10.3762/bjoc.12.260

• asymmetric version of this arylation reaction with various chiral ligands (see Scheme 2 and Supporting Information File 1, Table S3, for a detailed screening table). Among them, Box-type ligands have demonstrated a good performance in this reaction, affording low to good enantioselectivities. We began our

• ), [Ir(ppy)2(dtbbpy)]PF6 (0.001 mmol), CuBr2 (0.02 mmol), DCE (0.5 mL), under argon atmosphere. Design light-mediated arylation of THIQs. Evaluation of chiral ligands. Proposed reaction mechanism. Optimization of reaction conditionsa. Effect of chiral ligand on the enantioselectivity of coupling of N

Stereo- and regioselectivity of the hetero-Diels–Alder reaction of nitroso derivatives with conjugated dienes

• Lucie Brulíková,
• Aidan Harrison,
• Marvin J. Miller and
• Jan Hlaváč

Beilstein J. Org. Chem. 2016, 12, 1949–1980, doi:10.3762/bjoc.12.184

• are able to complex a nitroso derivative with chiral ligands (Scheme 37). Approach based on the in situ generation and trapping of an intermediate acylnitroso dienophile: This approach is exemplified by the results of the Iwasa group from 2008. They performed asymmetric hetero-Diels–Alder reactions of

Catalytic asymmetric synthesis of biologically important 3-hydroxyoxindoles: an update

• Bin Yu,
• Hui Xing,
• De-Quan Yu and
• Hong-Min Liu

Beilstein J. Org. Chem. 2016, 12, 1000–1039, doi:10.3762/bjoc.12.98