Prins cyclization-mediated stereoselective synthesis of tetrahydropyrans and dihydropyrans: an inspection of twenty years

• Asha Budakoti,
• Pradip Kumar Mondal,
• Prachi Verma and
• Jagadish Khamrai

Beilstein J. Org. Chem. 2021, 17, 932–963, doi:10.3762/bjoc.17.77

• methyl ricinoleate (127) with various aldehydes to produce 2,3,6-trialkyl-substituted 4-chlorotetrahydropyran 128 with excellent stereocontrol in all-cis-configuration (Scheme 30) [66]. The stereochemical outcome of this cyclization was rationalized by a chair-like transition state to produce

• Alder’s chair-like transition state 227 in which the (Z)-alkene accounts for the trans-stereocontrol at the C3 position and equatorial iodide addition accounts for the cis-stereocontrol at the C4 position, as shown below in Scheme 54. The one-pot synthesis of tetrahydropyran by utilizing the Babier–Prins

Synthetic reactions driven by electron-donor–acceptor (EDA) complexes

• Zhonglie Yang,
• Yutong Liu,
• Kun Cao,
• Xiaobin Zhang,
• Hezhong Jiang and
• Jiahong Li

Beilstein J. Org. Chem. 2021, 17, 771–799, doi:10.3762/bjoc.17.67

• protocol reveals a high functional-group tolerance that permits the transformation into boronic esters of natural alcohol products with high stereocontrol. The construction of C–N bonds The development of efficient methods to construct C–N bonds is an essential scheme in organic synthesis due to its

α,γ-Dioxygenated amides via tandem Brook rearrangement/radical oxygenation reactions and their application to syntheses of γ-lactams

• Mikhail K. Klychnikov,
• Radek Pohl,
• Ivana Císařová and
• Ullrich Jahn

Beilstein J. Org. Chem. 2021, 17, 688–704, doi:10.3762/bjoc.17.58

• -diastereoselectivity. Opposite absolute configurations in both components, 7 and 8, are displaying a synergistic effect for optimal stereocontrol in the radical oxygenation step with TEMPO (3). A good diastereoselectivity of the oxygenation was also observed for the formation of 9l (cf. Table 2). Assuming a preferred

Progress in the total synthesis of inthomycins

• Bidyut Kumar Senapati

Beilstein J. Org. Chem. 2021, 17, 58–82, doi:10.3762/bjoc.17.7

• -catalyzed hydroboration of the terminal acetylene in 127 gave (E,E)-128 in good yield and with complete stereocontrol (Scheme 18). To accomplish the key Suzuki coupling of dienylboronic ester 128, the necessary alkenyl iodides (Z)- and (E)-130 were prepared from the propargyl alcohol (14) in good yields

All-carbon [3 + 2] cycloaddition in natural product synthesis

• Zhuo Wang and
• Junyang Liu

Beilstein J. Org. Chem. 2020, 16, 3015–3031, doi:10.3762/bjoc.16.251

• enantioselective synthesis of marcfortine C (9, Scheme 4B). Another brilliant example is the development of a chiral-phosphine-catalyzed [3 + 2] annulation reported by Lu in 2019, in which the chiral phosphine catalyst confers high stereocontrol on the formation of a spiro adduct bearing two vicinal all-carbon

Asymmetric Mannich reactions of (S)-N-tert-butylsulfinyl-3,3,3-trifluoroacetaldimines with yne nucleophiles

• Ziyi Li,
• Li Wang,
• Yunqi Huang,
• Haibo Mei,
• Hiroyuki Konno,
• Hiroki Moriwaki,
• Vadim A. Soloshonok and
• Jianlin Han

Beilstein J. Org. Chem. 2020, 16, 2671–2678, doi:10.3762/bjoc.16.217

• expand our knowledge of the reactivity of imines and the origins of stereocontrol, as well as provide synthetic access to a series of trifluoromethylpropargylamine of high biological interest. Results and Discussion Drawing from our previous studies on the chemistry of trifluoromethylated sulfinylimine 1

• excellent level (>90% de) of stereocontrol reported for the Mannich additions of aldimine 1 with sp3 [42][55] and sp2 [56] nucleophiles, including lithiated aromatics [57] one would not anticipate such a dramatic drop in the selectivity in the reactions of sp nucleophiles. Accordingly, we considered the

• sulfinyl oxygen and the oxygen electron lone pair. The latter presents a lesser steric obstacle rendering the corresponding nucleophilic attack the more probable event. These ever-unexpected results strongly suggest that the origin of the stereocontrol in the reactions of imine 1 is not just the bulk of

Synthesis of novel fluorinated building blocks via halofluorination and related reactions

• Attila Márió Remete,
• Tamás T. Novák,
• Melinda Nonn,
• Matti Haukka,
• Ferenc Fülöp and
• Loránd Kiss

Beilstein J. Org. Chem. 2020, 16, 2562–2575, doi:10.3762/bjoc.16.208

• Deoxo-Fluor®. The fluorine-containing products thus obtained were subjected to elimination reactions, yielding various fluorine-containing small-molecular entities. Keywords: fluorine; fluoroselenation; functionalization; halofluorination; stereocontrol; Introduction The effects of fluorine on

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

• –carbon (C–C) bond-forming reactions play a key role in organic chemistry. Hereby the stereoselectivity of the reaction is highly important due to the different behavior of stereoisomers in human metabolism [1][2]. Stereocontrol was achieved either via an auxiliary [3][4][5][6][7] or a catalyst [8], both

• Diels–Alder reaction [21][22] and (2) a chiral ligand 2-H2 for the stereocontrol [13]. Cleaving the complex under acidic conditions resulted in the desired enantiomerically enriched product 9 and enabled the recovery of the chiral ligand 2-H2 (Scheme 2) [13]. The solvent choice allowed on/off-switching

• stereocontrol and achiral catalytically active ligands. Enamine-catalyzed nitro-Michael reactions The nitro-Michael reaction [37][38][39][40] seemed to be suitable to be performed at hierarchically assembled helicates due to the reaction’s “benchmark character” [41]. Therefore, ligands bearing secondary amine

Syntheses of spliceostatins and thailanstatins: a review

• William A. Donaldson

Beilstein J. Org. Chem. 2020, 16, 1991–2006, doi:10.3762/bjoc.16.166

• with a poor stereoselectivity, however, a similar reduction of the diethyl acetal of 38, followed by an acetal hydrolysis gave the aldehyde 39 with a good stereocontrol (>10:1). It is not possible to make a direct comparison of the efficiency of these three routes as they do not lead to an identical

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

Recent synthesis of thietanes

• Jiaxi Xu

Beilstein J. Org. Chem. 2020, 16, 1357–1410, doi:10.3762/bjoc.16.116

• stereocontrol were obtained when 316 was reacted with electron-rich olefins, as for example, vinyl ethers [87] (Scheme 58). In 2003, Sakamoto and co-coworkers investigated the intermolecular diastereoselective photo [2 + 2] cycloaddition of axially chiral monothiosuccinimides 319 which could enantiomerize into

Highly selective Diels–Alder and Heck arylation reactions in a divergent synthesis of isoindolo- and pyrrolo-fused polycyclic indoles from 2-formylpyrrole

• Carlos H. Escalante,
• Eder I. Martínez-Mora,
• Carlos Espinoza-Hicks,
• Alejandro A. Camacho-Dávila,
• Fernando R. Ramos-Morales,
• Francisco Delgado and
• Joaquín Tamariz

Beilstein J. Org. Chem. 2020, 16, 1320–1334, doi:10.3762/bjoc.16.113

• in governing the endo stereocontrol. Keywords: endo-Diels–Alder stereocontrol; 2-formylpyrrole; intramolecular Heck arylation reaction; non-covalent interactions; pyrroloindoles; pyrroloisoindoles; Introduction Pyrrolizines [1][2] and pyrrolizidines [3][4], abundant in nature [4][5], are among the

• out to provide additional insights into the factors controlling the endo outcome [53][82][83][84][85], documenting in some cases a key role of NCIs in the preferential stereocontrol [86]. Conclusion The Diels–Alder reaction of N-substituted-2-vinylpyrroles 8a–j and N-unsubstituted-2-vinylpyrroles 16a

Combining enyne metathesis with long-established organic transformations: a powerful strategy for the sustainable synthesis of bioactive molecules

• Valerian Dragutan,
• Ileana Dragutan,
• Albert Demonceau and
• Lionel Delaude

Beilstein J. Org. Chem. 2020, 16, 738–755, doi:10.3762/bjoc.16.68

• -metathesis, and a one-pot, two-step stereoselective conjugated allylic alcohol substitution (Scheme 26). It should be emphasized that in this convergent synthesis of (−)-exiguolide, the authors achieved a rigorous stereocontrol of both the exocyclic and endocyclic double bond geometries, as well as the

Recent advances in Cu-catalyzed C(sp³)–Si and C(sp³)–B bond formation

• Balaram S. Takale,
• Ruchita R. Thakore,
• Elham Etemadi-Davan and
• Bruce H. Lipshutz

Beilstein J. Org. Chem. 2020, 16, 691–737, doi:10.3762/bjoc.16.67

• cyclobutyl boronates in high yields and with excellent stereocontrol [101]. This work followed on the heels of earlier studies on the borylation of 2,6-disubstituted p-quinone methides en route to enantioenriched mono- and dibenzylic boronates [102]. An efficient regio-divergent method starting from a single

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

• described, allowing to produce the highly functionalized deoxypropionate fragment 30 in good overall yields and excellent stereocontrol for all stereogenic centers (up to 98:2 dr). α,β-Unsaturated acylimidazoles The pioneering and successful use of α,β-unsaturated acylimidazoles as Michael acceptors in

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

• renaissance by virtue of its greenness, sustainability, atom economy, step economy and inherent safety. Achieving stereocontrol in such organic electrochemical reactions remains a major synthetic challenge and hence demands great expertise. This review provides a comprehensive discussion of the details of

• chemistry. In this review, we aim to focus on methods for achieving stereocontrol in synthetic organic electrochemistry via a systematic description of the reported literature on chiral inductors, followed by their applications in the synthesis of natural products and bioactive compounds including late

• oxidation. The radical–radical coupling reaction between 101 and 95 is proposed to afford the corresponding intermediate 102. Then release of the Lewis acid catalyst gives the final product 97. The stereocontrol step is related to the in situ generation of radicals with π-systems of chiral enamines and

Enantioselective Diels–Alder reaction of anthracene by chiral tritylium catalysis

• Qichao Zhang,
• Jian Lv and
• Sanzhong Luo

Beilstein J. Org. Chem. 2019, 15, 1304–1312, doi:10.3762/bjoc.15.129

• of a highly active carbocation Lewis acid catalyst. The stereocontrol potential of the chiral tritylium ion pair was demonstrated by its application in an enantioselective Diels–Alder reaction of anthracene. Keywords: anthracene; carbocation catalysis; Diels–Alder reaction; Fe(III)-based phosphate

• synthesize stabilized chiral carbocations with chirality installed onto their backbones. Pioneering efforts along this line by Kagan, Sammakia, and Chen have shown that chiral catalysis with such chiral carbocations was indeed plausible to achieve stereocontrol (Scheme 1a). [14][15][16][17][18][19]. However

Syntheses and chemical properties of β-nicotinamide riboside and its analogues and derivatives

• Mikhail V. Makarov and
• Marie E. Migaud

Beilstein J. Org. Chem. 2019, 15, 401–430, doi:10.3762/bjoc.15.36

• , which eventually leads to improved stereocontrol. Treatment of 2,3,5-tri-O-acetyl-β-ethyl nicotinate riboside 17 with 4 N methanolic ammonia at 4 °C resulted in the simultaneous removal of the acetyl groups and the conversion of the ethyl nicotinate to the corresponding amide. A mechanistic study of

Unexpected loss of stereoselectivity in glycosylation reactions during the synthesis of chondroitin sulfate oligosaccharides

• Teresa Mena-Barragán,
• José L. de Paz and
• Pedro M. Nieto

Beilstein J. Org. Chem. 2019, 15, 137–144, doi:10.3762/bjoc.15.14

• trifluoroacetyl signals (δ = −75.62 and −75.93 ppm in 14α; δ = −75.85 and −75.89 ppm in 14β). The loss of stereocontrol in this glycosylation reaction was an unexpected result. The N-TFA group is considered as a participating group leading to the selective formation of 1,2-trans glycosidic linkages [37][45][46

Ring-opening metathesis of some strained bicyclic systems; stereocontrolled access to diolefinated saturated heterocycles with multiple stereogenic centers

• Zsanett Benke,
• Melinda Nonn,
• Márton Kardos,
• Santos Fustero and
• Loránd Kiss

Beilstein J. Org. Chem. 2018, 14, 2698–2707, doi:10.3762/bjoc.14.247

• stereocontrol, through the conservation of the configuration of the stereogenic centers of the starting compounds. Keywords: functionalization; heterocycles; metathesis; ring opening; stereogenic centers; Introduction Metathesis reactions, among them ring-opening metathesis (ROM), have received a great deal

• important segment of organic and pharmaceutical chemistry. Therefore, selective syntheses with stereocontrol of such scaffolds [11][12], such as highly-functionalized olefinated derivatives [13], are of main importance and a major challenge in synthetic organic chemistry. Thus, ring-opening metathesis is a

• -based catalysts. The bicyclic systems, derived from various cyclodienes, such as lactone, lactam or isoxazoline derivatives, were investigated under ROM through ethenolysis, which afforded novel dialkenylated scaffolds formed under stereocontrol with the conservation of the configuration of the

DFT calculations on the mechanism of copper-catalysed tandem arylation–cyclisation reactions of alkynes and diaryliodonium salts

• Tamás Károly Stenczel,
• Ádám Sinai,
• Zoltán Novák and
• András Stirling

Beilstein J. Org. Chem. 2018, 14, 1743–1749, doi:10.3762/bjoc.14.148

• : stabilisation of the vinyl cation [17][42] may induce a deviation toward a path with less efficient stereocontrol. To obtain further insight into the mechanism we have calculated these paths for a large number of reactions where the R1, R2 and R3 substituents of the reactants are varied (see reaction scheme in

Hypervalent organoiodine compounds: from reagents to valuable building blocks in synthesis

• Gwendal Grelier,
• Benjamin Darses and
• Philippe Dauban

Beilstein J. Org. Chem. 2018, 14, 1508–1528, doi:10.3762/bjoc.14.128

• ) [108]. The overall process affords complex nitrogen-containing compounds 92 with very good yields and complete stereocontrol starting from benzylic, allylic and adamantyl substrates. In addition, the preparation of substituted [bis(acyloxy)iodo]arenes following the reaction of iodoarenes with sodium

Diastereoselective auxiliary- and catalyst-controlled intramolecular aza-Michael reaction for the elaboration of enantioenriched 3-substituted isoindolinones. Application to the synthesis of a new pazinaclone analogue

• Romain Sallio,
• Stéphane Lebrun,
• Frédéric Capet,
• Francine Agbossou-Niedercorn,
• Christophe Michon and
• Eric Deniau

Beilstein J. Org. Chem. 2018, 14, 593–602, doi:10.3762/bjoc.14.46

• intramolecular aza-Michael reaction by means of both a chiral auxiliary and a catalyst for stereocontrol is reported for the synthesis of optically active isoindolinones. A selected cinchoninium salt was used as phase-transfer catalyst in combination with a chiral nucleophile, a Michael acceptor and a base to

• efficient stereocontrol. To the best of our knowledge such approach involving a double auxiliary and catalyst stereocontrol was never applied before to asymmetric synthesis of enantioenriched isoindolinones. Results and Discussion Retrosynthetic analysis From a retrosynthetic point of view, (3S)-NH free 3

Novel amide-functionalized chloramphenicol base bifunctional organocatalysts for enantioselective alcoholysis of meso-cyclic anhydrides

• Lingjun Xu,
• Shuwen Han,
• Linjie Yan,
• Haifeng Wang,
• Haihui Peng and
• Fener Chen

Beilstein J. Org. Chem. 2018, 14, 309–317, doi:10.3762/bjoc.14.19

• stereocontrol in alcoholytic catalytic asymmetric desymmetrizations of meso-cyclic anhydrides is of special interest [1][2][3][4][5][6][7]. Major families originating from natural products include cinchona alkaloids [8][9][10][11][12][13][14][15][16][17] and proteinogenic α-amino acids such as proline [18][19

Aminosugar-based immunomodulator lipid A: synthetic approaches

• Alla Zamyatina

Beilstein J. Org. Chem. 2018, 14, 25–53, doi:10.3762/bjoc.14.3