Non-noble metal-catalyzed cross-dehydrogenation coupling (CDC) involving ether α-C(sp³)–H to construct C–C bonds

• Hui Yu and
• Feng Xu

Beilstein J. Org. Chem. 2023, 19, 1259–1288, doi:10.3762/bjoc.19.94

• chemoselective and regioselective CDC between pyridines and ethers, which used Sc(OTf)3 as the catalyst and DTBP as the oxidant (Scheme 36) [101]. This strategy allowed the synthesis of a series of α-substituted pyridine derivatives. The control experiments showed that the mechanism may proceed via a radical

Enabling artificial photosynthesis systems with molecular recycling: A review of photo- and electrochemical methods for regenerating organic sacrificial electron donors

• Grace A. Lowe

Beilstein J. Org. Chem. 2023, 19, 1198–1215, doi:10.3762/bjoc.19.88

• sacrificial donors [40]. More recently, other groups have published the electrochemical hydrogenation of carbonyl compounds using more earth-abundant electrocatalysts. For instance, Siewert and co-worker used a manganese complex as an electrocatalyst for the chemoselective carbonyl hydrogenation [41

Exploring the role of halogen bonding in iodonium ylides: insights into unexpected reactivity and reaction control

• Carlee A. Montgomery and
• Graham K. Murphy

Beilstein J. Org. Chem. 2023, 19, 1171–1190, doi:10.3762/bjoc.19.86

• understood. Intramolecular halogen bonds might be expected to block the proximal (strong) σ-hole and prevent fluoride addition at that site (64a, Figure 14); however, computational results suggested that adduct formation at the strong σ-hole was key to the chemoselective reductive elimination of the

Photoredox catalysis harvesting multiple photon or electrochemical energies

• Mattia Lepori,
• Simon Schmid and
• Joshua P. Barham

Beilstein J. Org. Chem. 2023, 19, 1055–1145, doi:10.3762/bjoc.19.81

• generation of reactive intermediates for both oxidative and reductive processes via photon activation of a catalyst. Although this represents a significant step towards chemoselective and, more generally, sustainable chemistry, its efficacy is limited by the energy of visible light photons. Nowadays

Clauson–Kaas pyrrole synthesis using diverse catalysts: a transition from conventional to greener approach

• Dileep Kumar Singh and
• Rajesh Kumar

Beilstein J. Org. Chem. 2023, 19, 928–955, doi:10.3762/bjoc.19.71

• chemoselective procedure in which the iodine counterion and MeCN played key roles in the unique reactivity of this catalytic system. To optimize the reaction conditions, many catalysts, solvents, and temperatures were studied and finally, 10 mol % MgI2∙(OEt2)n as the catalyst, CH3CN as the solvent, and 80 °C

Honeycomb reactor: a promising device for streamlining aerobic oxidation under continuous-flow conditions

• Masahiro Hosoya,
• Yusuke Saito and
• Yousuke Horiuchi

Beilstein J. Org. Chem. 2023, 19, 752–763, doi:10.3762/bjoc.19.55

• , their harsh and hazardous conditions impede their application to complex molecules. Thus, a variety of mild and chemoselective oxidations have been developed, including Swern oxidation [5], tetrapropylammonium perruthenate (TPAP) oxidation [6], Pinnick oxidation [7], and 2,2,6,6-tetramethylpiperidinyl-1

Asymmetric synthesis of a stereopentade fragment toward latrunculins

• Benjamin Joyeux,
• Antoine Gamet,
• Nicolas Casaretto and
• Bastien Nay

Beilstein J. Org. Chem. 2023, 19, 428–433, doi:10.3762/bjoc.19.32

• , in view of its coupling to 8. We first relied the chemoselective epoxidation of the homoallylic alcohol, done in presence of VO(OiPr)3 (20 mol %) and t-BuOOH to afford epoxide 13, in 86% yield and a dr of 75:25 (measured by NMR, presumably resulting from the major diastereoisomer of 13; minor isomers

1,4-Dithianes: attractive C2-building blocks for the synthesis of complex molecular architectures

• Bram Ryckaert,
• Ellen Demeyere,
• Frederick Degroote,
• Hilde Janssens and
• Johan M. Winne

Beilstein J. Org. Chem. 2023, 19, 115–132, doi:10.3762/bjoc.19.12

• chemoselective and stereospecific mild hydrodesulfurization with Raney nickel in acetic acid affords the target compound 59 as a single Z-diastereomer. Interestingly, glacial acetic acid proved to be the only solvent that could avoid both undesired overreduction and cis–trans isomerization of the alkene bond. It

• reactivity of the sulfur atoms does allow many mild and chemoselective manipulations. For 1,4-dithianes, the literature for selective functional group transformations and deprotections is obviously less extensive than for 1,3-dithianes, but the various reports that can be found also point towards the fact

• some experimentation, the desired chemoselective transformation can be achieved in almost all cases, including for sensitive substrates such as yohimbine-derived compound 102 [30]. A common problem is the concomitant hydrogenation of alkenes, which can be hard to avoid, as seen in the

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

• chemoselective manner [3]. The development of persistent radicals [4] as synthons in chemical synthesis, coupled with the advancements in generating and manipulating transient radicals [5] as cross-coupling partners in an array of chemical reactions, gives access to a wide variety of “new” retrosynthetic

• conceptualized by Renata’s group to access various oxidized members of pyrone meroterpenoids. The divergent plan of Renata’s group depended on the development of a highly chemoselective, chemoenzymatic 3-hydroxylation of sclareolide (29) and (−)-sclareol (43, Scheme 3 and Scheme 4). The group began by conducting

• -fused tetracycle instead, were reported to possess NF-kB-inhibitory activity and anticancer activity against NCI H-929 cancer cell lines (Scheme 6) [39]. In 2021 Lu’s group reported the total synthesis of members of both meroterpenoid families based on a highly chemoselective α-alkylation in the

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

• ][78][95] less reactive and less electron-deficient N-oxyl radicals (usually isolable and storable amine-N-oxyl radicals) are used as precursors of the active oxidants, oxoammonium cations. This oxidative organocatalysis type is highly important for the chemoselective oxidation of alcohols. Two

• electrolysis (2–3 F/mol) until potential rised by 0.5–0.8 V above initial potential; undivided cell, reticulated vitreous carbon (RVC) anode(+):Pt cathode(−). Chemoselective alcohol oxidation catalyzed by TEMPO. ABNO-catalyzed oxidative C–N coupling of primary alcohols with primary amines. ACT-catalyzed

B–N/B–H Transborylation: borane-catalysed nitrile hydroboration

• Filip Meger,
• Alexander C. W. Kwok,
• Franziska Gilch,
• Dominic R. Willcox,
• Alex J. Hendy,
• Kieran Nicholson,
• Andrew D. Bage,
• Thomas Langer,
• Thomas A. Hunt and
• Stephen P. Thomas

Beilstein J. Org. Chem. 2022, 18, 1332–1337, doi:10.3762/bjoc.18.138

• noted that the borohydride-catalysed reductions generally proceed at lower reaction temperatures using 5 mol % NaBHEt3 [24]. Esters undergo stoichiometric reduction by H3B·SMe2 (see Supporting Information File 1) [32]; therefore, chemoselective nitrile hydroboration highlights the benefit of this

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

• for different purposes in the syntheses of a range of oxindole alkaloids. The start of the synthesis of (rac)-corynoxine (76) was the conversion of tryptamine (70) to oxindole 71, which was used in a chemoselective Mannich reaction with aldehyde 72, introducing the α-ketoester moiety (Scheme 12) [27

Electrochemical hydrogenation of enones using a proton-exchange membrane reactor: selectivity and utility

• Koichi Mitsudo,
• Haruka Inoue,
• Yuta Niki,
• Eisuke Sato and
• Seiji Suga

Beilstein J. Org. Chem. 2022, 18, 1055–1061, doi:10.3762/bjoc.18.107

• -unsaturated acids [25] and the reduction of benzoic acids [26]. We have been interested in electrochemical transformations for a long time [27][28][29][30][31] and are paying the most attention to the utility of PEM reactors for organic syntheses, especially chemoselective transformations. In our research, we

• should be controllable by the cathode catalyst and electrochemical parameters. Fortunately, we found that chemoselective reduction of enones 1 can be carried out using different cathode catalysts (Pd/C or Ir/C). Results and Discussion Electroreduction of enones to ketones First, we chose cyclohex-2-en-1

• conditions, and highly chemoselective reductions were achieved with the use of appropriate cathode catalysts. The use of a Pd/C cathode gave carbonyl compounds selectively. In contrast, saturated alcohols were obtained selectively with an Ir/C cathode. The reaction with H2O as a proton source was also

Automated grindstone chemistry: a simple and facile way for PEG-assisted stoichiometry-controlled halogenation of phenols and anilines using N-halosuccinimides

• Dharmendra Das,
• Akhil A. Bhosle,
• Amrita Chatterjee and
• Mainak Banerjee

Beilstein J. Org. Chem. 2022, 18, 999–1008, doi:10.3762/bjoc.18.100

• catalyst-free halogenation of phenols and anilines via liquid-assisted grinding using PEG-400 as the grinding auxiliary. A series of mono-, di-, and tri-halogenated phenols and anilines was synthesized in good to excellent yields within 10–15 min in a chemoselective manner by controlling the stoichiometry

• halogenation without much substituent effect and by just controlling the stoichiometry of NXS a series of mono-, di-, and trihalogenated phenols and anilines were obtained in a chemoselective manner in good to excellent yields within 2–15 min of grinding. Spontaneous decarboxylation (or desulfonation) was

Tosylhydrazine-promoted self-conjugate reduction–Michael/aldol reaction of 3-phenacylideneoxindoles towards dispirocyclopentanebisoxindole derivatives

• Sayan Pramanik and
• Chhanda Mukhopadhyay

Beilstein J. Org. Chem. 2022, 18, 469–478, doi:10.3762/bjoc.18.49

• and operational simplicity through one pot reaction. Keywords: chemoselective conjugate reduction; dispirocyclopentanebisoxindole scaffolds; metal-free; one-pot operation; reductive cyclization; Introduction There is a vast demand of the structurally complex spirooxindole scaffold which is an

• important functional group transformation for the synthesis of heterocyclic and carbocyclic building blocks and reactive intermediates. Besides the use of various reducing agents, it is observed that tosylhydrazine develops the transition-metal-free and highly chemoselective conjugate reduction of α,β

• the In(III)-catalyzed reductive cyclization of isatylidene malononitriles using the Hantzsch ester as reducing agent for the synthesis of dispirocyclopentanebisoxindole. Our work utilizes tosylhydrazine as chemoselective reducing agent for 3-phenacylideneoxindoles and thereafter base-catalyzed

Recent developments and trends in the iron- and cobalt-catalyzed Sonogashira reactions

• Surendran Amrutha,
• Sankaran Radhika and
• Gopinathan Anilkumar

Beilstein J. Org. Chem. 2022, 18, 262–285, doi:10.3762/bjoc.18.31

• -supported heterogeneous Fe(III) catalyst. Suggested catalytic cycle for the Sonogashira coupling using a silica-supported heterogeneous Fe(III) catalyst. Chemoselective iron-catalyzed cross coupling of 4-bromo-1-cyclohexen-1-yltrifluromethane sulfonate with (tert-butyl dimethylsilyl)ethynylmagnesium bromide

Flow synthesis of oxadiazoles coupled with sequential in-line extraction and chromatography

• Kian Donnelly and
• Marcus Baumann

Beilstein J. Org. Chem. 2022, 18, 232–239, doi:10.3762/bjoc.18.27

• chemoselective in the presence of other oxidisable moieties such as in the cases of 2i and 2j. Additionally, the stereoconfiguration of the styryl moiety was maintained as confirmed via the X-ray structure of 2j (Scheme 3). As a potential application of our previously reported synthesis of useful bicyclo[1.1.1

Chemoselective N-acylation of indoles using thioesters as acyl source

• Tianri Du,
• Xiangmu Wei,
• Honghong Xu,
• Xin Zhang,
• Ruiru Fang,
• Zheng Yuan,
• Zhi Liang and
• Yahui Li

Beilstein J. Org. Chem. 2022, 18, 89–94, doi:10.3762/bjoc.18.9

• requires sensitive and reactive acyl chloride derivatives. Here, we report a mild, efficient, functional group tolerant, and highly chemoselective N-acylation of indoles using thioesters as a stable acyl source. A series of indoleamides have been obtained with moderate to good yields. In addition

• cannabinoid (hCB1) receptor [3] (Figure 1). Indole has multiple reactive sites, and chemoselective N- or C-functionalization of indoles is a challenging and important task [4][5]. Acylation of indoles frequently takes place at the C3 position because of the relatively strong electron cloud density. As N

• efficient method for the synthesis of N-acylindoles becomes much attractive [9][10][11][12]. In 2009, Scheidt developed a dehydrogenative approach using indoles and alcohols catalyzed by tetrapropylammonium perruthenate [13] (Scheme 1, A1). In 2012, Sarpong successfully carried out chemoselective acylation

Iron-catalyzed domino coupling reactions of π-systems

• Austin Pounder and
• William Tam

Beilstein J. Org. Chem. 2021, 17, 2848–2893, doi:10.3762/bjoc.17.196

• solvent-tuned [129]. In neat CH2Cl2, the reaction produced the expected β-trichloromethyl alkyl azide; however, the reaction was chemoselective for diazidation when tert-butanol was used as co-solvent. The authors hypothesized the presence of the alcohol suppresses the polar-unmatched HAT process from

Selective sulfonylation and isonitrilation of para-quinone methides employing TosMIC as a source of sulfonyl group or isonitrile group

• Chuanhua Qu,
• Run Huang,
• Yong Li,
• Tong Liu,
• Yuan Chen and
• Guiting Song

Beilstein J. Org. Chem. 2021, 17, 2822–2831, doi:10.3762/bjoc.17.193

• 402160, China 10.3762/bjoc.17.193 Abstract Chemoselective sulfonylation and isonitrilation reactions for the divergent synthesis of valuable diarylmethyl sulfones and isonitrile diarylmethanes starting from easy-to-synthesize para-quinone methides (p-QMs) and commercially abundant p

• synthetic utility of this protocol was also demonstrated in the synthesis of difluoroalkylated diarylmethane 5 and diarylmethane ketone derivatives 6 and 7, which are important core structures in natural products and medicines. Keywords: chemoselective reactions; diarylmethyl sulfones; dual role

• report the chemoselective sulfonylation and isonitrilation of p-QMs by changing the reaction conditions. This new general protocol allows, from the same substrates p-QMs 1 and p-tosylmethyl isocyanide (TosMIC, 2a), the formation of quite different products 3 or 4 in a simple and mild manner, which

Recent advances in the tandem annulation of 1,3-enynes to functionalized pyridine and pyrrole derivatives

• Yi Liu,
• Puying Luo,
• Yang Fu,
• Tianxin Hao,
• Xuan Liu,
• Qiuping Ding and
• Yiyuan Peng

Beilstein J. Org. Chem. 2021, 17, 2462–2476, doi:10.3762/bjoc.17.163

• (Scheme 10) [52]. The tandem reaction involved a regio- and chemoselective addition of the Blaise reaction intermediate to 1,3-enyne, and the following sequential processes: isomerization, cyclization, and aromatization. Both carbocyclic and acyclic 1,3-enyenes 28 were compatible to give the corresponding

Strategies for the synthesis of brevipolides

• Yudhi D. Kurniawan and
• A'liyatur Rosyidah

Beilstein J. Org. Chem. 2021, 17, 2399–2416, doi:10.3762/bjoc.17.157

• into the PMB-protected α,β-unsaturated ester 97 in four steps adopting the literature procedure (Scheme 12). The chemoselective reduction of the olefin in 97 was furnished in 88% yield applying NiCl4·6H2O/NaBH4 as reagents in methanol followed by reduction of the ester part with DIBAL-H providing the

A study on selective transformation of norbornadiene into fluorinated cyclopentane-fused isoxazolines

• Zsanett Benke,
• Attila M. Remete and
• Loránd Kiss

Beilstein J. Org. Chem. 2021, 17, 2051–2066, doi:10.3762/bjoc.17.132

• . Some commercial Ru-based catalysts used in the current work. Synthesis of divinylated cyclopentane-fused isoxazolines [41]. Various fluorine-containing olefins used in the current work. Chemoselective CM reaction due to steric hindrance. Cross-metathesis of divinylated isoxazoline (±)-4 with

On the application of 3d metals for C–H activation toward bioactive compounds: The key step for the synthesis of silver bullets

• Renato L. Carvalho,
• Amanda S. de Miranda,
• Mateus P. Nunes,
• Roberto S. Gomes,
• Guilherme A. M. Jardim and
• Eufrânio N. da Silva Júnior

Beilstein J. Org. Chem. 2021, 17, 1849–1938, doi:10.3762/bjoc.17.126

• reaction showed to be chemoselective, maintaining good yields with compounds bearing varied functional groups, whereas low yields were observed for benzylic fluorination. Preliminary mechanistic studies suggested the C–H abstraction to be the rate-determining step and the high oxygen sensitivity of the

• applied in some very sophisticated protocols including several examples reported by the White group. In 2015, White and co-workers reported a new catalytic method using manganese tert-butylphthalocyanine [Mn(t-BuPc)Cl] for the chemoselective intramolecular amination of various C(sp3)–H bond types like

Sustainable manganese catalysis for late-stage C–H functionalization of bioactive structural motifs

• Jongwoo Son

Beilstein J. Org. Chem. 2021, 17, 1733–1751, doi:10.3762/bjoc.17.122

• azidation product 11. Upon regeneration, the catalyst participates in the next catalytic cycle. In this Mn-catalyzed azidation study, the azide/oxygenated product ratio was 2:1–4:1. Therefore, a chemoselective manner is of dire need to avoid unwanted C–H oxygenation. In 2020, the Lei group disclosed the

• molecules bearing unactivated Csp3–H bonds facilitated by electricity (Scheme 5) [43]. Several pharmaceutically active molecules were committed to the external oxidant-free reaction conditions and were shown to undergo chemoselective azidation. Azidation of ibuprofen methyl ester (14a) was selective for the

• acetate as the base to deliver the corresponding peptide–sugar conjugates 31 at the late stage. Notably, the chemoselective glycoconjugation strategy was compatible with various sugar scaffolds, affording glycotryptophans bearing either furanose or pyranose motifs. In addition, a brevianamide F analogue