Combining the best of both worlds: radical-based divergent total synthesis

• Kyriaki Gennaiou,
• Antonios Kelesidis,
• Maria Kourgiantaki and
• Alexandros L. Zografos

Beilstein J. Org. Chem. 2023, 19, 1–26, doi:10.3762/bjoc.19.1

• asymmetric conjugate reaction of commercially available 81 and 82 using Fletcher’s protocol (94% ee) [44]. A subsequent intramolecular arylation in the α-position of the ketone of 83, catalyzed by a Pd(II)–NHC [45], followed by methylation, provided cis-decalin 84 (Scheme 7). Appropriate redox modifications

• distributed in Southeast Asia and China [70]. Compounds of this class are traditionally used for detoxification and as anti-inflammatory agents in Chinese medicine [71]. Qin and co-workers reported the asymmetric total syntheses of several eburnane alkaloids. Therein, they relied on one of their previous

• (–)-eburnaminol (132), (+)-larutenine (133), (–)-terengganensine B (134), and (–)-strempeliopine (136), as well as the asymmetric formal total synthesis of (–)-terengganensine A (not shown, Scheme 11). The requisite common synthetic intermediate 129 for the cascade was accessed by an acid-promoted condensation of

Inclusion complexes of the steroid hormones 17β-estradiol and progesterone with β- and γ-cyclodextrin hosts: syntheses, X-ray structures, thermal analyses and API solubility enhancements

• Alexios I. Vicatos,
• Zakiena Hoossen and
• Mino R. Caira

Beilstein J. Org. Chem. 2022, 18, 1749–1762, doi:10.3762/bjoc.18.184

• which no single crystals of adequate diffraction quality were isolated. The asymmetric units (ASUs) of β-CD·BES and β-CD·PRO (Figure 6) each consist of a single β-CD molecule, one severely disordered guest molecule (either 17β-estradiol for β-CD·BES, or progesterone for β-CD·PRO), and water molecules

• host–guest complexation, as a consequence of a mutual-induced fit of host and guest molecules [39]. With reference to γ-CD·PRO, the asymmetric unit (ASU) comprises three pairs of glucose rings that generate three complete γ-CD molecules when rotation of these units around the four-fold axis parallel to

Synthetic study toward tridachiapyrone B

• Morgan Cormier,
• Florian Hernvann and
• Michaël De Paolis

Beilstein J. Org. Chem. 2022, 18, 1741–1748, doi:10.3762/bjoc.18.183

• yield was actually noted with (PhSe)2 as electrophile, 5 being obtained in 62% yield, enabling thus an evaluation of the next desymmetrization step. An overview of the scientific literature revealed that, while the asymmetric desymmetrization of prochiral 2,5-cyclohexadienones is a rich topic of

Total synthesis of grayanane natural products

• Nicolas Fay,
• Rémi Blieck,
• Cyrille Kouklovsky and
• Aurélien de la Torre

Beilstein J. Org. Chem. 2022, 18, 1707–1719, doi:10.3762/bjoc.18.181

• . This first total synthesis of principinol D, in 19 steps as the longest linear sequence, is asymmetric even though a separation of the mixture of diastereomers resulting from fragment coupling is necessary. The SmI2-mediated reductive ring-closure of the 7-membered ring is among the most remarkable

• cyclization based on a bridgehead tertiary carbocation intermediate forging the B ring; iii) redox manipulations and a 1,2-migration as final steps. The synthesis started from (S)-ketone 44 which was prepared via asymmetric CBS reduction of diketone 26 (Scheme 7). Firstly, this (S)-ketone 44 was transformed

Redox-active molecules as organocatalysts for selective oxidative transformations – an unperceived organocatalysis field

• Elena R. Lopat’eva,
• Igor B. Krylov,
• Dmitry A. Lapshin and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2022, 18, 1672–1695, doi:10.3762/bjoc.18.179

• organic chemistry. It allows chemists to avoid the use of precious and (or) toxic metals by taking advantage of the catalytic activity of small and synthetically available molecules. Today, the term organocatalysis is mainly associated with redox-neutral asymmetric catalysis of C–C bond-forming processes

• redox-neutral asymmetric organocatalysis, whereas organocatalysis by redox-active molecules stays in the shadows. For example, redox-active organic molecules are almost not mentioned in some recent overviews of compound types used in organocatalysis [3][12][13], except for photoredox catalysts [12][13

• organocatalysis in general. Examples of typical reaction types for redox-neutral asymmetric organocatalysis are aldol reactions [13], Michael reactions [14][15][16], and Diels–Alder reactions [17][18]. The processes associated with changing oxidation states of atoms in substrates thus can be named “redox

Rhodium-catalyzed intramolecular reductive aldol-type cyclization: Application for the synthesis of a chiral necic acid lactone

• Motoyuki Isoda,
• Kazuyuki Sato,
• Kenta Kameda,
• Kana Wakabayashi,
• Ryota Sato,
• Hideki Minami,
• Yukiko Karuo,
• Atsushi Tarui,
• Kentaro Kawai and
• Masaaki Omote

Beilstein J. Org. Chem. 2022, 18, 1642–1648, doi:10.3762/bjoc.18.176

• , the reductive aldol-type reaction could also be applied to an asymmetric system, although the diastereoselectivity was poor. On the other hand, reductive Mannich-type reactions were achieved in good to excellent yields with high diastereoselectivity [45][46]. As part of a wider program of C–C bond

One-pot double annulations to confer diastereoselective spirooxindolepyrrolothiazoles

• Juan Lu,
• Bin Yao,
• Desheng Zhan,
• Zhuo Sun,
• Yun Ji and
• Xiaofeng Zhang

Beilstein J. Org. Chem. 2022, 18, 1607–1616, doi:10.3762/bjoc.18.171

• ]. Pyrrolothiazole and spirooxindole moieties occupy exclusive positions as valuable source of natural products and therapeutic agents in organic synthesis and drug discovery [60][61][62][63][64][65][66][67][68]. We have developed a number of asymmetric reactions to construct spirooxindole-based scaffolds through

Comparison of crystal structure and DFT calculations of triferrocenyl trithiophosphite’s conformance

• Ruslan P. Shekurov,
• Mikhail N. Khrizanforov,
• Ilya A. Bezkishko,
• Tatiana P. Gerasimova,
• Almaz A. Zagidullin,
• Daut R. Islamov and
• Vasili A. Miluykov

Beilstein J. Org. Chem. 2022, 18, 1499–1504, doi:10.3762/bjoc.18.157

• by X-ray single-crystal diffraction. Triferrocenyl trithiophosphite has nine axes of internal rotation: three P–S bonds, three C–S bonds and three Fe–cyclopentadienyl axes. Rotation around the P–S bonds results in a totally asymmetric structure with three ferrocenylthio groups exhibiting different

Design, synthesis, and evaluation of chiral thiophosphorus acids as organocatalysts

• Karen R. Winters and
• Jean-Luc Montchamp

Beilstein J. Org. Chem. 2022, 18, 1471–1478, doi:10.3762/bjoc.18.154

• asymmetric organocatalysis. In order to eliminate the need for C2-symmetry in common CPAs, various scaffolds containing C1-symmetrical thiophosphorus acids were chosen. These new compounds were synthesized and evaluated in the asymmetric transfer hydrogenation of 2-phenylquinoline. Although the efficacy of

• the thiophosphorus acids was disappointing for this reaction, the work should be useful for developing structural design elements. Keywords: asymmetric; heterocycles; organocatalysis; phosphorus; synthesis; Introduction The importance of asymmetric organocatalysis was demonstrated by the 2021 Nobel

• SPINOL [4][5] (Figure 1). The great success of these CPAs in asymmetric organocatalysis, is demonstrated by the publication of thousands of articles and reviews [6][7][8][9][10][11][12][13][14][15][16][17]. In all cases the C2-symmetry is required because of the prototropic tautomeric equilibrium in the

Supramolecular approaches to mediate chemical reactivity

• Pablo Ballester,
• Qi-Qiang Wang and
• Carmine Gaeta

Beilstein J. Org. Chem. 2022, 18, 1463–1465, doi:10.3762/bjoc.18.152

• the synthesis and properties of such BINOL-based chiral MIMs, together with their use in further diastereoselective modifications, their application in asymmetric catalysis, and stereoselective chemosensing. In their minireview, Prodip Howlader and Michael Schmittel [22] highlighted the recent results

Mechanochemical synthesis of unsymmetrical salens for the preparation of Co–salen complexes and their evaluation as catalysts for the synthesis of α-aryloxy alcohols via asymmetric phenolic kinetic resolution of terminal epoxides

• Shengli Zuo,
• Shuxiang Zheng,
• Jianjun Liu and
• Ang Zuo

Beilstein J. Org. Chem. 2022, 18, 1416–1423, doi:10.3762/bjoc.18.147

• as an enantioselective catalyst for the asymmetric ring opening of terminal epoxides by phenols. A library of α-aryloxy alcohols 3 was thereafter synthesized in good yield and high ee using 2f via the phenolic KR of epichlorohydrin. Keywords: α-aryloxy alcohols; chiral Co–salen; HKR

• enantioselective synthesis in modern chemistry turns out to be accumulatively essential for the preparation of chiral drugs, which is a huge growing market in the future. Indeed, the asymmetric ring opening of terminal epoxides is one of the most important strategies for synthesizing drug-like building blocks and

• key organic intermediates in the drug discovery and process chemistry [4][5][6]. Chiral metal–salen complexes were designed for catalyzing reaction processes that resulted in good yield, high regioselective and enantioselective control for the asymmetric ring opening of terminal epoxides. Various

Preparation of an advanced intermediate for the synthesis of leustroducsins and phoslactomycins by heterocycloaddition

• Anaïs Rousseau,
• Guillaume Vincent and
• Cyrille Kouklovsky

Beilstein J. Org. Chem. 2022, 18, 1385–1395, doi:10.3762/bjoc.18.143

• Boc-protection of the nitrogen atom, cycloadduct 8 was obtained in 55% yield and 90% ee. Therefore, the combination of both these reagents should provide a quick and selective access to the central fragment of leustroducsins/phoslactomycins. Results and Discussion Asymmetric cycloaddition Preliminary

• have therefore completed a quick, efficient and selective access to the central core of leustroducsins/phoslactomycins using an asymmetric nitroso Diels–Alder reaction. This fragment displays a ketone function that will be used for coupling with the lactone fragment 3 by generation of the tertiary

• alcohol. Studies in fragment coupling We have previously reported the synthesis of the lactone fragment by catalytic asymmetric [2 + 2] cycloaddition followed by ring extension [18]. The initial product was the TMS-acetylene 18 which could be easily desilylated to give 21. However, model studies for

Synthesis and electrochemical properties of 3,4,5-tris(chlorophenyl)-1,2-diphosphaferrocenes

• Almaz A. Zagidullin,
• Farida F. Akhmatkhanova,
• Mikhail N. Khrizanforov,
• Robert R. Fayzullin,
• Tatiana P. Gerasimova,
• Ilya A. Bezkishko and
• Vasili A. Miluykov

Beilstein J. Org. Chem. 2022, 18, 1338–1345, doi:10.3762/bjoc.18.139

• objects of growing interest in the fields of coordination chemistry [3][4][5] and asymmetric catalysis [6][7]. Due to the sp2-hybridization of the phosphorus atom, phosphaferrocenes are commonly regarded as phosphorus ligands with weaker σ-donor character than classical tertiary phosphines and stronger π

• mediator in the synthesis of asymmetric phosphines starting from white phosphorus [15]. Moreover, the presence of the lone pair of the P atom opens the route to polynuclear complexes [16][17][18] and coordination polymers [19][20][21] with the mixed σ-/π-coordination mode, which is not typical for

Vicinal ketoesters – key intermediates in the total synthesis of natural products

• Marc Paul Beller and
• Ulrich Koert

Beilstein J. Org. Chem. 2022, 18, 1236–1248, doi:10.3762/bjoc.18.129

• (−)-irofulven (87), Movassaghi et al. used a CuII-catalyzed asymmetric aldol reaction of O-silyl ketene S,O-acetal 84 with methyl pyruvate (85) to enantioselectively install the crucial tertiary TMS-protected alcohol in ester 86 (Scheme 14) [29]. Eleven further steps gave (−)-irofulven (87). 2. Mesoxalic

• reactivity in their synthesis of (+)-awajanomycin (92), a marine natural product with a γ-lactone-δ-lactam core structure (Scheme 15) [30][31]. Key step was an asymmetric allylboration of diethyl mesoxalate (90a) with boronate 89, which was easily accessible through a Matteson homologation of dichloromethyl

Derivatives of benzo-1,4-thiazine-3-carboxylic acid and the corresponding amino acid conjugates

• Péter Kisszékelyi,
• Tibor Peňaška,
• Klára Stankovianska,
• Mária Mečiarová and
• Radovan Šebesta

Beilstein J. Org. Chem. 2022, 18, 1195–1202, doi:10.3762/bjoc.18.124

• either the salt 16a·HCl or the free amine 16a in good to excellent yield (Scheme 3). We also explored the asymmetric catalytic hydrogenation of adduct 14. Our first attempt at the reduction using organocatalyzed transfer hydrogenation was unsuccessful (see Supporting Information File 1). The (R)-Ru(OAc)2

Lewis acid-catalyzed Pudovik reaction–phospha-Brook rearrangement sequence to access phosphoric esters

• Jin Yang,
• Dang-Wei Qian and
• Shang-Dong Yang

Beilstein J. Org. Chem. 2022, 18, 1188–1194, doi:10.3762/bjoc.18.123

• examined a series of reactions of symmetric and asymmetric secondary phosphine oxides with 2-pyridinecarboxaldehyde (2a), which produced the corresponding O-phosphination products (Scheme 2). Diarylphosphine oxide substrates with either electron-withdrawing or electron-donating groups tethered to the

Introducing a new 7-ring fused diindenone-dithieno[3,2-b:2',3'-d]thiophene unit as a promising component for organic semiconductor materials

• Valentin H. K. Fell,
• Joseph Cameron,
• Alexander L. Kanibolotsky,
• Eman J. Hussien and
• Peter J. Skabara

Beilstein J. Org. Chem. 2022, 18, 944–955, doi:10.3762/bjoc.18.94

• had sizes of ca. 100 nm, while the crystallites in films obtained by on-centre spin-coating had smaller sizes of ca. 20 nm. The same core alkylated on only one side resulted in the asymmetric 2-tridecyl[1]benzothieno[3,2-b][1]-benzothiophene (9) [28]. In polycrystalline films obtained by thermal

• asymmetric analogue, which is only alkylated on one side (9), achieved OFET hole mobilities up to 17.22 cm2 V−1 s−1 in polycrystalline films obtained by thermal evaporation [28]; both examples prove the potential of thienoacenes in OFETs. ITIC, a system with fused thiophenes, in combination with donor

On Reuben G. Jones synthesis of 2-hydroxypyrazines

• Pierre Legrand and
• Yves L. Janin

Beilstein J. Org. Chem. 2022, 18, 935–943, doi:10.3762/bjoc.18.93

• was simplified later on by the use of the hydrochloride salts of the α-aminoamides 2, instead of their free base, along with the addition of a second equivalent of sodium hydroxide [13]. As expected, from asymmetric 1,2-diketones (1, R1 ≠ R2 and ≠ H), reports [14][15][16] describe the occurrence of

Synthetic strategies for the preparation of γ-phostams: 1,2-azaphospholidine 2-oxides and 1,2-azaphospholine 2-oxides

• Jiaxi Xu

Beilstein J. Org. Chem. 2022, 18, 889–915, doi:10.3762/bjoc.18.90

• as starting materials, realizing an unprecedented asymmetric induction in the synthesis of cyclohexadiene-fused γ-phosphinolactams 126–131, through the formation of configurationally stable lithium salts. When aldehydes 125 were applied as electrophiles, three new stereocenters were generated in the

• complex showed 23% enantiomeric excess in the asymmetric borane reduction of acetophenone in THF at room temperature (Scheme 33) [58]. The reaction of 3-(phenylaminomethylene)-2-phenylamino-6-methyl-2,3-dihydro-4H-chromen-4-one (213) and diethyl phosphite at 90–100 °C generated 2-ethoxy-6-methyl-2-oxo-1

• + 1] Annulations have been mainly utilized in the construction of the 1,2-azaphospholidine ring, while the [3 + 2] annulation has been seldomly used in the synthesis of pyridine-fused 1,2-azaphospholidine 2-oxide only. Few asymmetric synthetic methods have been developed to date. Thus, highly

Synthesis of bis-spirocyclic derivatives of 3-azabicyclo[3.1.0]hexane via cyclopropene cycloadditions to the stable azomethine ylide derived from Ruhemann's purple

• Alexander S. Filatov,
• Olesya V. Khoroshilova,
• Anna G. Larina,
• Vitali M. Boitsov and
• Alexander V. Stepakov

Beilstein J. Org. Chem. 2022, 18, 769–780, doi:10.3762/bjoc.18.77

• asymmetric 1,3-dipolar cycloaddition of azomethine ylides and cyclopropenes catalyzed by a chiral Cu-(CH3CN)4BF4/Ph-Phosferrox complex for the construction of 3-azabicyclo[3.1.0]hexane derivatives [25]. Another concise enantioselective approach towards 3-azabicyclo[3.1.0]hexanes is based on a Cp*Ir-catalyzed

Inductive heating and flow chemistry – a perfect synergy of emerging enabling technologies

• Conrad Kuhwald,
• Sibel Türkhan and
• Andreas Kirschning

Beilstein J. Org. Chem. 2022, 18, 688–706, doi:10.3762/bjoc.18.70

• materials to inductively heat up glass reactors. For the Biginelli reaction solubility of the starting urea (22) as well as the products 24a and 24b were an issue being overcome by using a solvent mixture of PEG/DMF 1:1. Also the proline-catalyzed asymmetric Mannich reaction was achieved with cyclohexanone

Heteroleptic metallosupramolecular aggregates/complexation for supramolecular catalysis

• Prodip Howlader and
• Michael Schmittel

Beilstein J. Org. Chem. 2022, 18, 597–630, doi:10.3762/bjoc.18.62

• catalysts has been successfully developed employing dynamic metal–ligand coordination bonds. While only a small fraction of these 3D architectures was useful for chiral catalysis, an even smaller fraction was able to provide a high stereoselectivity during asymmetric catalysis [5]. For instance, an

• that the chiral moiety should be incorporated in the ligand unit in order to provide an enantiopure assembly with an asymmetric cavity. 1,1'-Binaphthol (BINOL) is one such chiral building block, which has been successfully utilized to carry out numerous asymmetric catalytic reactions [74]. Keeping this

• differently sized triangles (S)-40 and (S)-41 depending on the length of the organic spacer in the acceptor unit (Figure 9) [75]. Since the interior cavity of the homochiral macrocycles was equipped with BINOL units, they were utilized as catalysts for the asymmetric conjugate addition of chalcone 42 with

A study of the photochemical behavior of terarylenes containing allomaltol and pyrazole fragments

• Constantine V. Milyutin,
• Andrey N. Komogortsev,
• Boris V. Lichitsky and
• Valeriya G. Melekhina

Beilstein J. Org. Chem. 2022, 18, 588–596, doi:10.3762/bjoc.18.61

• experiments (HSQC, HMBC, COSY). Interestingly, in the 1H NMR spectrum of the product 14a the aromatic protons of the 4-methoxyphenyl substituent are represented as four singlets due to the presence of an asymmetric center and the hindered rotation of the aryl substituent relative to the pyrazole ring. The

BINOL as a chiral element in mechanically interlocked molecules

• Matthias Krajnc and
• Jochen Niemeyer

Beilstein J. Org. Chem. 2022, 18, 508–523, doi:10.3762/bjoc.18.53

• '-binaphthyl-2,2'-diol (BINOL) unit as a stereogenic element in mechanically interlocked molecules (MIMs). We describe the synthesis and properties of such BINOL-based chiral MIMs, together with their use in further diastereoselective modifications, their application in asymmetric catalysis, and their use in

• chemosensing or in asymmetric catalysis. The selection of suitable stereogenic elements is of great importance [26][27][28]. The most straightforward way to create a chiral rotaxane or catenane is the introduction of classical chiral elements, such molecular parts with axial chirality, point chirality, or

• described in chapter 1, the mechanical bond allows a chirality transfer from a chiral, BINOL-based macrocycle to an achiral thread. Thus, it is conceivable that placing a catalytically active group onto the thread would allow for asymmetric catalysis based on chirality transfer from a BINOL macrocycle. In

Bioinspired tetraamino-bisthiourea chiral macrocycles in catalyzing decarboxylative Mannich reactions

• Hao Guo,
• Yu-Fei Ao,
• De-Xian Wang and
• Qi-Qiang Wang

Beilstein J. Org. Chem. 2022, 18, 486–496, doi:10.3762/bjoc.18.51

• tertiary amine sites were found to be crucial for achieving efficient activation and stereocontrol. As shown in control experiments, catalysis with the acyclic analogues having the same structural motifs were non-selective. Keywords: chiral macrocycles; cooperative asymmetric catalysis; decarboxylative

• cavity could resemble the circumstance of the catalytic triad of Polyketide synthases (PKSs) [40][41][42] (Figure 1). On the other hand, the organocatalytic asymmetric decarboxylative addition reactions of MAHTs to imines provide an efficient means for accessing valuable chiral β-amino esters [43][44][45