Development and mechanistic studies of calcium–BINOL phosphate-catalyzed hydrocyanation of hydrazones

• Carola Tortora,
• Christian A. Fischer,
• Sascha Kohlbauer,
• Alexandru Zamfir,
• Gerd M. Ballmann,
• Jürgen Pahl,
• Sjoerd Harder and
• Svetlana B. Tsogoeva

Beilstein J. Org. Chem. 2025, 21, 755–765, doi:10.3762/bjoc.21.59

• moiety are non-linear with a Ca–N–C angle of 100°. Due to the stereospecificity of the reaction, racemization would have to occur already in 9 through a topomerization (e.g., similar to a Berry pseudorotation) of the metal complex, considering that species with a quaternary carbon, as they appear in

Recent advances in allylation of chiral secondary alkylcopper species

• Minjae Kim,
• Gwanggyun Kim,
• Doyoon Kim,
• Jun Hee Lee and
• Seung Hwan Cho

Beilstein J. Org. Chem. 2025, 21, 639–658, doi:10.3762/bjoc.21.51

• bearing quaternary stereogenic centers with high stereospecificity. This methodology represents a significant advancement in the construction of challenging all-carbon quaternary stereogenic centers through stereospecific allylic substitution reactions. To elucidate the origin of the selective boron group

1,2-Difluoroethylene (HFO-1132): synthesis and chemistry

• Liubov V. Sokolenko,
• Taras M. Sokolenko and
• Yurii L. Yagupolskii

Beilstein J. Org. Chem. 2024, 20, 1955–1966, doi:10.3762/bjoc.20.171

• ][88]. In Table 3, reaction data are summarized to show the scope and limitations of this process. An interesting feature of this reaction is the high stereospecificity. In almost all cases, the addition proceeded syn-specific, yielding the erythro-isomer from cis- and the threo-isomer from trans-1,2

Benzylic C(sp³)–H fluorination

• Alexander P. Atkins,
• Alice C. Dean and
• Alastair J. J. Lennox

Beilstein J. Org. Chem. 2024, 20, 1527–1547, doi:10.3762/bjoc.20.137

• demonstrate stereospecificity, again on predefined substrate classes. Radical fluorination methods offer an expansion to substrate scopes and rely on the use of more expensive fluorine-atom-transfer reagents. Finally, oxidative benzylic activation methods, often in tandem with enabling technologies, such as

Ligand effects, solvent cooperation, and large kinetic solvent deuterium isotope effects in gold(I)-catalyzed intramolecular alkene hydroamination

• Ruichen Lan,
• Brock Yager,
• Yoonsun Jee,
• Cynthia S. Day and
• Amanda C. Jones

Beilstein J. Org. Chem. 2024, 20, 479–496, doi:10.3762/bjoc.20.43

• protodemetalation pathway is also supported by kinetics and reactivity studies on generated palladium alkyl intermediates [47]. Formation of alkylgold intermediates is known to proceed with anti-attack [27] and the stereospecificity observed in deuterium-labeled intermediates was used as an argument for

Revisiting the bromination of 3β-hydroxycholest-5-ene with CBr₄/PPh₃ and the subsequent azidolysis of the resulting bromide, disparity in stereochemical behavior

• Christian Schumacher,
• Jas S. Ward,
• Kari Rissanen,
• Carsten Bolm and
• Mohamed Ramadan El Sayed Aly

Beilstein J. Org. Chem. 2023, 19, 91–99, doi:10.3762/bjoc.19.9

• inversion. For note, the 1H NMR spectrum of 5 revealed the presence of ca. 15% of the β-epimer 6, which could result from an incomplete stereospecificity of the substitution opening an alternative reaction path. Also in this case, the NMR data are then in agreement with the reported ones [18]. In light of

• . Stereospecific reaction of 11 with bromide as nucleophile leads to 4, in which the halo substituent is located on the β-side of the molecule. Treatment of 4 with NaN3 in DMF at 90–100 °C provides predominantly azide 5 [23]. This reaction has a high stereospecificity as well, proceeding mostly with inversion of

Complementarity of solution and solid state mechanochemical reaction conditions demonstrated by 1,2-debromination of tricyclic imides

• Petar Štrbac and
• Davor Margetić

Beilstein J. Org. Chem. 2022, 18, 746–753, doi:10.3762/bjoc.18.75

• (0.6:1), and slightly more in favor of the unsymmetrical adduct 20. On the other hand, the reaction of cyclopentadiene (21) provided the linear exo,exo-cycloadduct 22 as the major product, together with the 2:1 adduct 23. In this reaction, identical stereospecificity was obtained by employment of the

• Zn/Ag couple in THF [19]. Linear exo,exo-product 25 was obtained exclusively in the reaction with DPIBF 24, which is in accordance to the stereospecificity of cycloadditions reported by Sasaki [25] where the linear adduct is greatly preferred over bent. An interesting feature of the 1H NMR spectrum

A consensus-based and readable extension of Linear Code for Reaction Rules (LiCoRR)

• Benjamin P. Kellman,
• Yujie Zhang,
• Emma Logomasini,
• Eric Meinhardt,
• Karla P. Godinez-Macias,
• Austin W. T. Chiang,
• James T. Sorrentino,
• Chenguang Liang,
• Bokan Bao,
• Yusen Zhou,
• Sachiko Akase,
• Isami Sogabe,
• Thukaa Kouka,
• Elizabeth A. Winzeler,
• Iain B. H. Wilson,
• Matthew P. Campbell,
• Sriram Neelamegham,
• Frederick J. Krambeck,
• Kiyoko F. Aoki-Kinoshita and
• Nathan E. Lewis

Beilstein J. Org. Chem. 2020, 16, 2645–2662, doi:10.3762/bjoc.16.215

• comfortably accommodate those currently working in systems glycobiology. We also provide some key definitions for ease of reading (Figure 1, Table 2). Syntax Rules of the Original Linear Code Linear Code rules can be separated into six categories of syntax rules (Table 3): Stereospecificity and ring structure

• rules (SRS), modification rules (MR), branch rules (BR), repetition rules (RR), glycoconjugate rules (GR), and uncertainty rules (UR). The saccharide unit (SU) refers to a structure with four elements: anomericity, position number, modifications, and monosaccharide (MS). Stereospecificity and ring

• structure rules are set to differentiate the stereoisomers or distinct ring structures. A change from primary to secondary stereospecificity is denoted by “ ’ ”, while a change to secondary ring structure is denoted “ ^ ”. A change to both secondary ring and stereospecificity is denoted “ ~ ”. For example

Why do thioureas and squaramides slow down the Ireland–Claisen rearrangement?

• Dominika Krištofíková,
• Juraj Filo,
• Mária Mečiarová and
• Radovan Šebesta

Beilstein J. Org. Chem. 2019, 15, 2948–2957, doi:10.3762/bjoc.15.290

• stereospecificity make this transformation synthetically appealing [12][13]. Allyl esters of various carboxylic acids undergo rearrangement as their lithium enolates or silyl ketene acetals and the corresponding acids were isolated in 75–80% yields. Accordingly, the Ireland–Claisen rearrangement of lithium enolates

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

• ]. The resulting chiral trifluoromethylated alkynes were acquired with high regioselectivity and stereospecificity (ees up to >99%). Furthermore, this reaction showed a broad substrate scope, as well as excellent functional-group compatibility (Scheme 57). A possible mechanism was proposed: firstly

Borylation and rearrangement of alkynyloxiranes: a stereospecific route to substituted α-enynes

• Ruben Pomar Fuentespina,
• José Angel Garcia de la Cruz,
• Gabriel Durin,
• Victor Mamane,
• Jean-Marc Weibel and
• Patrick Pale

Beilstein J. Org. Chem. 2019, 15, 1416–1424, doi:10.3762/bjoc.15.141

• elimination [15] (Scheme 1). We also demonstrated the stereospecificity of these transformations [16]. α-Enynes (1,3-enynes) are an interesting class of compounds in organic chemistry as these structures are found in various pharmacologically active natural products [17], and in functional materials [18]. α

• relationship between the starting oxirane and the enyne product was always obtained, whatever the group transferred from boron to the oxirane carbon. These results revealed the stereospecificity of the reaction and suggested that no epimerization of the oxiranyllithium intermediate occurred. The present

• the above results, we conclude that the alkynyloxirane-to-enyne reaction is stereospecific, maintaining the stereochemistry of the starting oxirane in the resulting enyne. This stereospecificity imposes the stereochemical integrity of the oxiranyllithium species formed upon lithiation, but also the

Olefin metathesis in multiblock copolymer synthesis

• Maria L. Gringolts,
• Yulia I. Denisova,
• Eugene Sh. Finkelshtein and
• Yaroslav V. Kudryavtsev

Beilstein J. Org. Chem. 2019, 15, 218–235, doi:10.3762/bjoc.15.21

• the parent homopolymers are exhausted. 1H NMR spectroscopy was implemented to track the evolution of the chain structure in the course of MCM between polybutadiene (PBD) or polyisoprene (PI) and olefin-containing polyesters or polyurethane, as well as changes in the chain stereospecificity during the

Thermophilic phosphoribosyltransferases Thermus thermophilus HB27 in nucleotide synthesis

• Ilja V. Fateev,
• Ekaterina V. Sinitsina,
• Aiguzel U. Bikanasova,
• Maria A. Kostromina,
• Elena S. Tuzova,
• Larisa V. Esipova,
• Tatiana I. Muravyova,
• Alexei L. Kayushin,
• Irina D. Konstantinova and
• Roman S. Esipov

Beilstein J. Org. Chem. 2018, 14, 3098–3105, doi:10.3762/bjoc.14.289

• the preparation of nucleosides and nucleotides due to the regio- and stereospecificity of enzymes [4][10][11], performing metabolic transformations of substrates. Phosphoribosyltransferases are increasingly being widely used as key enzymes in multi-enzymatic systems [2]. The substrate specificity of

The enzymes of microbial nicotine metabolism

• Paul F. Fitzpatrick

Beilstein J. Org. Chem. 2018, 14, 2295–2307, doi:10.3762/bjoc.14.204

• to that of LHNO and several members of the MAO family, consistent with Nox being a nicotine oxidase similar to NicA2. Nox is reported to be able to oxidize both stereoisomers of nicotine equally well, in contrast to the stereospecificity of LHNO and DHNO. Pseudooxynicotine amine oxidase, the enzyme

Recent advances in synthetic approaches for medicinal chemistry of C-nucleosides

• Kartik Temburnikar and
• Katherine L. Seley-Radtke

Beilstein J. Org. Chem. 2018, 14, 772–785, doi:10.3762/bjoc.14.65

• Vorbrüggen coupling reaction [66], the synthesis of C-nucleosides typically gives a mixture of stereoisomers (α and β) at the anomeric carbon [48][49][54][62][67][68]. Since the naturally occurring nucleosides (and most biologically active nucleosides) are β-anomers, achieving 100% stereospecificity in C–C

Electrochemical Corey–Winter reaction. Reduction of thiocarbonates in aqueous methanol media and application to the synthesis of a naturally occurring α-pyrone

• Ernesto Emmanuel López-López,
• José Alvano Pérez-Bautista,
• Fernando Sartillo-Piscil and
• Bernardo A. Frontana-Uribe

Beilstein J. Org. Chem. 2018, 14, 547–552, doi:10.3762/bjoc.14.41

• functionality [34], which was not reduced under the reaction conditions. The high stereospecificity of this electrochemical Corey–Winter-type reaction might be explained in terms of the stabilizing β-oxygen effect [35][36] of the radical intermediate E. This stereoelectronic interaction, which refers to the

Enzymatic synthesis of glycosides: from natural O- and N-glycosides to rare C- and S-glycosides

• Jihen Ati,
• Pierre Lafite and
• Richard Daniellou

Beilstein J. Org. Chem. 2017, 13, 1857–1865, doi:10.3762/bjoc.13.180

• molecular biology have allowed the emergence of biocatalytic procedures. Enzymes have proven to be efficient synthetic tools for the eco-compatible synthesis of many classes of compounds. Non-organic solvents, mild experimental conditions, and high regio- or stereospecificity of the biocatalysed reaction

Strategies toward protecting group-free glycosylation through selective activation of the anomeric center

• A. Michael Downey and
• Michal Hocek

Beilstein J. Org. Chem. 2017, 13, 1239–1279, doi:10.3762/bjoc.13.123

• absence of a C2–OH group (Table 5, entries 5 and 6). The remarkable stereospecificity of this reaction coupled with its ability to provide C-glycosides, a class of compounds important in natural products [66] and drug design [67], makes this methodology a very powerful one. One very clear drawback

Polyketide stereocontrol: a study in chemical biology

• Kira J. Weissman

Beilstein J. Org. Chem. 2017, 13, 348–371, doi:10.3762/bjoc.13.39

• introduced primarily by methyl transferase domains [18], with presumably defined the stereospecificity (the stereochemistry is not always evident, as it can be obscured by subsequent dehydration). The suite of processing reactions also introduces stereochemistry into the molecules: the hydroxy groups

• excluded. Given the high level of homology among many AT domains from cis-AT PKSs [29], it is likely that all such acyl transferases exhibit the same stereospecificity. The AT domains operate by a ping-pong bi-bi mechanism [30], in which the initially formed acyl-O-AT intermediate is subject to

• hydrophobic interactions with the Tyr while being sterically accommodated by the relatively small Ser (Figure 7b). Finally, stereospecificity for the (2S)-isomer appears to lie in steric clashes that would occur between a (2R)-methyl group and both the Ser and His of the YASH motif. Nonetheless, efforts in

Combined experimental and theoretical studies of regio- and stereoselectivity in reactions of β-isoxazolyl- and β-imidazolyl enamines with nitrile oxides

• Ilya V. Efimov,
• Marsel Z. Shafikov,
• Nikolai A. Beliaev,
• Natalia N. Volkova,
• Tetyana V. Beryozkina,
• Wim Dehaen,
• Zhijin Fan,
• Viktoria V. Grishko,
• Gert Lubec,
• Pavel A. Slepukhin and
• Vasiliy A. Bakulev

Beilstein J. Org. Chem. 2016, 12, 2390–2401, doi:10.3762/bjoc.12.233

• 4i), respectively. The regio- and stereospecificity and the apparent reaction rate increase by the introduction of electron-withdrawing substituents into the benzonitrile oxide structure, allow to presume that the reaction of enamines with nitrile oxides can be described as 1,3-dipolar cycloadditions

Interactions of cyclodextrins and their derivatives with toxic organophosphorus compounds

• Sophie Letort,
• Sébastien Balieu,
• William Erb,
• Géraldine Gouhier and
• François Estour

Beilstein J. Org. Chem. 2016, 12, 204–228, doi:10.3762/bjoc.12.23

• inclusion complexes is essential to get a catalytic activity. Stereospecificity, both in the formation of the inclusion complex and in the nucleophilic reaction, are also observed to some extent. According to the authors, the (S)-(+)-sarin (14b, Figure 5) forms a more stable inclusion complex than the (R

• )-(−)-sarin (14a, Figure 5), the latter being more easily hydrolyzed (Table 6). Thus, a better affinity with the CD cavity does not invariably imply a higher reaction rate. The comparison of the dissociation (Kd) and rate constants (k2) of the two sarin enantiomers clearly shows that the stereospecificity

• the inclusion complexes stereospecific formation is not significant, but that α-CD is predominantly phosphonylated by the (−)-enantiomers. The stereospecificity observed with sarin, isopropyl para-nitrophenyl methylphosphonate and isopropyl (S)-2-dimethylaminoethyl methylphosphonothioate is ascribed

Synthesis of 1,2-cis-2-C-branched aryl-C-glucosides via desulfurization of carbohydrate based hemithioacetals

• Henok H. Kinfe,
• Fanuel M. Mebrahtu,
• Mandlenkosi M. Manana,
• Kagiso Madumo and
• Mokela S. Sokamisa

Beilstein J. Org. Chem. 2015, 11, 583–588, doi:10.3762/bjoc.11.64

• hemithioacetals 5 (Scheme 3). The reaction provided the corresponding 2,3-unsaturated-α-aryl-C-glycosides 9a–c in excellent yields (Scheme 3). The high stereospecificity for an α-anomer, mild, non-acidic (alkaline) reaction conditions as well as absence of the need for transition metal reagents makes the current

Atherton–Todd reaction: mechanism, scope and applications

• Stéphanie S. Le Corre,
• Mathieu Berchel,
• Hélène Couthon-Gourvès,
• Jean-Pierre Haelters and
• Paul-Alain Jaffrès

Beilstein J. Org. Chem. 2014, 10, 1166–1196, doi:10.3762/bjoc.10.117

• subsequent attack of the nucleophilic substrate (amine, alcohol or thiophenol) occurred at the opposite side of the phosphorus–chlorine bond to afford the substitution product with high stereospecificity and an inversion of configuration. Zhao et al. have also investigated the stereochemistry of the AT

Theoretical studies on the intramolecular cyclization of 2,4,6-t-Bu₃C₆H₂P=C: and effects of conjugation between the P=C and aromatic moieties

• Masaaki Yoshifuji and
• Shigekazu Ito

Beilstein J. Org. Chem. 2014, 10, 1032–1036, doi:10.3762/bjoc.10.103

• phosphanylidenecarbenoid (Scheme 1) [11][12][13]. The phosphorus version of FBW rearrangement showed considerable stereospecificity in affording phosphaalkyne, which could be explicable by plausible reaction mechanisms including formation of the phosphavinyl anion intermediate without generation of phosphanylidenecarbene

New developments in gold-catalyzed manipulation of inactivated alkenes

• Michel Chiarucci and
• Marco Bandini

Beilstein J. Org. Chem. 2013, 9, 2586–2614, doi:10.3762/bjoc.9.294

• ]. Experiments with configurationally defined hydroxy allylic alcohols 105b,c demonstrated the stereospecificity of the process. Due to the complexity of the substrates, the stereochemical model proposed by Aponick [65] could only partially account for the stereochemical outcome of the reaction, since the

• benzoates. Intramolecular [Au(I)]-catalyzed cyclopropanation of alkenes. Stereospecificity in [Au(I)]-catalyzed hydroalkoxylation of allylic alcohols. Mechanistic investigation on the intramolecular [Au(I)]-catalyzed hydroalkoxylation of allylic alcohols. Mechanistic investigation on the intramolecular