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

Fluorination of some highly functionalized cycloalkanes: chemoselectivity and substrate dependence

• Attila Márió Remete,
• Melinda Nonn,
• Santos Fustero,
• Matti Haukka,
• Ferenc Fülöp and
• Loránd Kiss

Beilstein J. Org. Chem. 2017, 13, 2364–2371, doi:10.3762/bjoc.13.233

• fluorination based on hydroxy–fluorine interconversion seems to be an eloquent, simple and efficient procedure for the creation of a certain fluorinated organic molecule, regio- and stereoselectivity, stereocontrol and substrate influence remain a challenge in the case of highly functionalized frameworks

Homologated amino acids with three vicinal fluorines positioned along the backbone: development of a stereoselective synthesis

• Raju Cheerlavancha,
• Ahmed Ahmed,
• Yun Cheuk Leung,
• Aggie Lawer,
• Qing-Quan Liu,
• Marina Cagnes,
• Hee-Chan Jang,
• Xiang-Guo Hu and
• Luke Hunter

Beilstein J. Org. Chem. 2017, 13, 2316–2325, doi:10.3762/bjoc.13.228

• amino acid unit in a natural peptide without changing the overall length of the peptide [16]. The presence of three vicinal fluorine atoms on the amino acid backbone of 6 gives rise to eight possible stereoisomeric forms, which presents a synthetic challenge of stereocontrol. As an initial contribution

Intramolecular glycosylation

• Xiao G. Jia and
• Alexei V. Demchenko

Beilstein J. Org. Chem. 2017, 13, 2028–2048, doi:10.3762/bjoc.13.201

• for elaborate protecting and leaving group manipulations, functionalization, tedious purification, and sophisticated characterization. Achieving high stereocontrol in glycosylation reactions is arguably the major hurdle that chemists experience. This review article overviews methods for intramolecular

• very first experiments performed by Arthur Michael and Emil Fischer in the late 1800’s, the glycosylation reaction remains challenging to chemists. Enzymatic glycosylation reactions are highly stereoselective [33]. However, the stereocontrol of chemical glycosylation reactions remains cumbersome

• as a flattened oxacarbenium intermediate (Scheme 1a). Early attempts to achieve some stereocontrol of glycosylations were mainly dedicated to the development of participating groups and optimization of the reaction conditions. More recently, the research emphasis is switching towards understanding of

The chemistry and biology of mycolactones

• Matthias Gehringer and
• Karl-Heinz Altmann

Beilstein J. Org. Chem. 2017, 13, 1596–1660, doi:10.3762/bjoc.13.159

A speedy route to sterically encumbered, benzene-fused derivatives of privileged, naturally occurring hexahydropyrrolo[1,2-b]isoquinoline

• Olga Bakulina,
• Alexander Ivanov,
• Vitalii Suslonov,
• Dmitry Dar’in and
• Mikhail Krasavin

Beilstein J. Org. Chem. 2017, 13, 1413–1424, doi:10.3762/bjoc.13.138

• -diastereoselectivity of the CCR is well documented in the literature [33] and is, therefore, unsurprising. However, the stereocontrol achieved in this reaction over 3 stereocenters present in 10l (obtained in 81% yield as a single diastereomer) is certainly quite noteworthy and was confirmed by X-ray analysis (Figure

Polyketide stereocontrol: a study in chemical biology

• Kira J. Weissman

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

• biosynthesis of reduced polyketides in bacteria by modular polyketide synthases (PKSs) proceeds with exquisite stereocontrol. As the stereochemistry is intimately linked to the strong bioactivity of these molecules, the origins of stereochemical control are of significant interest in attempts to create

• this approach to provide answers to fundamental biological questions. Keywords: chemical biology; polyketide synthases; reduced polyketides; stereocontrol; Introduction Reduced polyketides and their derivatives form the basis for a number of medicines in current clinical usage, notably anti

• so in principle, 1024 (210) different stereoisomers are possible. Yet, nature reliably assembles only one stereoisomer (at least at detectable levels), at once revealing the strict stereocontrol underpinning the pathway and the importance of synthesizing this particular version. Indeed, the crystal

Silyl-protective groups influencing the reactivity and selectivity in glycosylations

• Mikael Bols and
• Christian Marcus Pedersen

Beilstein J. Org. Chem. 2017, 13, 93–105, doi:10.3762/bjoc.13.12

• the reaction intermediate is a radical that prefers to be axial. On the other hand, with acetate protective groups, the addition of deuterium occurred predominantly from the β-side [45][46]. The principle of conformational stereocontrol was also used for the stereoselective addition of carbon radicals

• C-glycosides it has been possible to obtain conformationally derived stereocontrol so that persilylated donors adopting a 1C4 conformation give the β-products. However, for O-glycosylation, this type of selectivity has been difficult to achieve. Some very useful stereoselectivities are obtained with

Strategies in asymmetric catalysis

• Tehshik P. Yoon

Beilstein J. Org. Chem. 2017, 13, 63–64, doi:10.3762/bjoc.13.8

• synthetic problems. The articles collected in this Thematic Series for the Beilstein Journal of Organic Chemistry provide a snapshot of both types of efforts. Several of these papers report new catalyst designs or relatively new concepts in catalytic stereocontrol. Others document the application of

Diastereoselective anodic hetero- and homo-coupling of menthol-, 8-methylmenthol- and 8-phenylmenthol-2-alkylmalonates

• Matthias C. Letzel,
• Hans J. Schäfer and
• Roland Fröhlich

Beilstein J. Org. Chem. 2017, 13, 33–42, doi:10.3762/bjoc.13.5

• coupling in high yield with good stereocontrol [38][39][40]. With the auxiliary controlled alkylation of enolates products being analogous to radical hetero-coupling can be synthesized [41][42]. However, both methods require costlier reaction conditions as inert gas, dry solvents and LDA as reagent, and

Useful access to enantiomerically pure protected inositols from carbohydrates: the aldohexos-5-uloses route

• Felicia D’Andrea,
• Giorgio Catelani,
• Lorenzo Guazzelli and
• Venerando Pistarà

Beilstein J. Org. Chem. 2016, 12, 2343–2350, doi:10.3762/bjoc.12.227

• derivatives of the D-xylo and L-ribo series, respectively C-4 and C-2 epimers of the L-arabino series. Based on these aldol condensations together with the work previously performed on the L-arabino [33] and L-lyxo [34] series, a working mechanism is presented to explain the complete stereocontrol over the

• formation of the two new stereogenic centres (red in Scheme 1). Furthermore, the stereochemical outcome of the intermediate inososes reduction by using different reagents, namely the stereocontrol over a third stereogenic centre (green in Scheme 1), is also reported. Results and Discussion The aldol