• Issue

    European Journal of Organic Chemistry: Volume 2021, Issue 9

    1305-1473
    March 5, 2021

Cover Pictures

Free Access

Front Cover: Perfluorophenyl-Perfluorophenyl Stacking-Promoted Aggregation-Induced Emission Enhancement of Crystalline 5-Aryloxy-3H-Indole (Eur. J. Org. Chem. 9/2021)

  • Pages: 1305
  • First Published: 25 February 2021
Description unavailable

The Front Cover shows a molecule that emits almost no fluorescence in the dilute solution but does emit blue light due to the overlap of two perfluorophenyl groups in crystalline states. It is expressed by making the castle glow blue by the overlapping of the two hands. We express gratitude to the workers who are devoted to medical care by illuminating the historic building. More information can be found in the Full Paper by K. Funabiki et al.

Free Access

Cover Feature: Atroposelective Synthesis of Isoriccardin C through a C−H Activated Heck Type Macrocyclization (Eur. J. Org. Chem. 9/2021)

  • Pages: 1306
  • First Published: 23 February 2021
Description unavailable

The Cover Feature shows a chiral sulfinyl auxiliary in the ortho-position of a biaryl axis inducing a C–H activated atroposelective macrocyclization with final transformation to the configurationally stable natural Isoriccardin C. More information can be found in the Communication by S. Choppin, A. Speicher et al.

Reviews

Very Important Paper

Chemistry for the Identification of Therapeutic Targets: Recent Advances and Future Directions

  • Pages: 1307-1320
  • First Published: 23 December 2020
Description unavailable

The earliest preclinical stages of drug discovery must generate information about the identity, the in vivo engagement, and the endogenous levels of the targeted protein(s). In this review, we outline the main strategies by which chemical probes, compounds that rely on chemical reactions to give an answer to specific biological questions, are contributing to currently challenging biomedical applications.

Minireviews

Non-Canonical Reactivity of Gold Carbene with Alkyne: An Overview of the Mechanistic Premise

  • Pages: 1321-1330
  • First Published: 16 January 2021
Description unavailable

Reactions of gold carbene with alkyne have been discussed with the emphasis on the possible mechanisms, while also focusing on the energetics of the key intermediates as studied in some of the crucial reports covered herein.

Oxidative Transformation of Biomass into Formic Acid

  • Pages: 1331-1343
  • First Published: 28 December 2020
Description unavailable

Formic acid is receiving attention as a promising hydrogen source as well as a valuable chemical for the industries of textiles, pharmaceuticals etc. This minireview is focused on the recent advancement in its formation from biomass, using oxidative pathways and different catalysts such as polyoxometalate, vanadium oxide, hydrothermal, and photocatalysis, developed over the past ten years.

Full Papers

Perfluorophenyl-Perfluorophenyl Stacking-Promoted Aggregation-Induced Emission Enhancement of Crystalline 5-Aryloxy-3H-Indole

  • Pages: 1344-1350
  • First Published: 14 January 2021
Description unavailable

Introduction of a perfluorophenyloxy group at the 5-position of 3,3-dibutyl-2-methyl-3H-indole efficiently promotes aggregation-induced emission enhancement in the crystalline solid state. The phenomenon is attributed to aggregate formation, arising from perfluorophenyl-perfluorophenyl stacking between the 3H-indole units.

Communications

Open Access

Atroposelective Synthesis of Isoriccardin C through a C−H Activated Heck Type Macrocyclization

  • Pages: 1351-1354
  • First Published: 11 January 2021
Description unavailable

A chiral sulfinyl auxiliary group in ortho-position of a biaryl axis is directing in the adjacent aryl moiety an atropo-diastereoselective ortho’-Fujiwara-Moritani Heck coupling with dynamic kinetic resolution and can finally be transformed into a hydroxyl function of a natural occurring cyclophane type bisbibenzyl.

Full Papers

Iridium Complexes as Efficient Catalysts for Construction of α-Substituted Ketones via Hydrogen Borrowing of Alcohols in Water

  • Pages: 1355-1364
  • First Published: 05 February 2021
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An iridium complexes-catalyzed cross-coupling of alcohols via hydrogen borrowing is reported, affording a series of α-alkylated ketones in high yield and chemoselectivities. Moreover, this methodology has the advantages of low catalyst loading and environmentally benign water as the solvent. In addition, a gram-scale experiment demonstrates the potential application in the practical synthesis of α-alkylated ketones.

Communications

Sulfonium Salts Enable the Direct Sulfenylation of Activated C(sp3)−H Bonds

  • Pages: 1365-1369
  • First Published: 20 January 2021
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The direct alkylsulfenylation of various activated C−H bonds has been reported. The reaction utilizes sulfonium salts as sulfenylation reagents which are readily prepared, operationally simple, and performe under mild reaction conditions.

Full Papers

Synthesis of Alkyl Bridged-Tris-α-Amino Acids as C3-Symmetric and Linear Linkers

  • Pages: 1370-1377
  • First Published: 25 January 2021
Description unavailable

The lack of suitable trivalent linkers has limited trimer peptide models. This study designed and synthesized two new alkyl bridged-tris-α-amino acids with Fmoc protecting groups as flexible linkers, which are characterized by C3-symmetric and linear structures, respectively.

One-Pot Synthesis of 5-Amino-1,2,3-triazole Derivatives via Dipolar Azide−Nitrile Cycloaddition and Dimroth Rearrangement under Solvent-Free Conditions

  • Pages: 1378-1384
  • First Published: 27 January 2021
Description unavailable

A series of novel 5-amino-1,2,3-triazole derivatives has been synthesized by combining a dipolar azide−nitrile cycloaddition with a Dimroth rearrangement under solvent-free conditions. Solvent-free approach for the synthesis of 5-amino-1,2,3-triazoles is reported for the first time.

Communications

Very Important Paper

Ruthenium(II)-Catalyzed C−H Activation/Annulation of Aromatic Hydroxamic Acid Esters with Enamides Leading to Aminal Motifs

  • Pages: 1385-1389
  • First Published: 29 January 2021
Description unavailable

An annulative coupling between aromatic hydroxamic acid esters and electron-rich olefins such as enamides has been developed for the production of valuable aminal frameworks under inexpensive ruthenium catalysis.

Full Papers

Arsenic-Bridged Silafluorene and Germafluorene as a Novel Class of Mixed-Heteroatom-Bridged Heterofluorenes

  • Pages: 1390-1395
  • First Published: 27 January 2021
Description unavailable

Arsenic-bridged silafluorene and germafluorene were synthesized as a new class of mixed-heteroatom-bridged heterofluorenes. The arsenic atom promoted intersystem crossing due to the heavy-atom effect to enhance phosphorescence.

Stereoselective Synthesis of (2S,6R)-Diamino-(5R,7)-dihydroxy-heptanoic Acid (DADH): An Unusual Amino Acid from Streptomyces sp. SANK 60404

  • Pages: 1396-1401
  • First Published: 15 January 2021
Description unavailable

Stereoselective synthesis of (2S,6R)-diamino-(5R,7)-dihydroxy-heptanoic acid (DADH) was achieved for the first time. The three stereogenic centers of DADH were constructed by chemical manipulation of Garner's aldehyde as a chiral source and chiral DuPHOS-Rh-catalyzed asymmetric hydrogenation of a dehydroamino acid ester. This method also enabled the flexible synthesis of the DADH stereoisomer from Garner's aldehyde.

Communications

Open Access

Klyflaccilins B-T, Polyoxgenated Eunicellins from the Soft Coral Klyxum flaccidum

  • Pages: 1402-1406
  • First Published: 16 January 2021
Description unavailable

Nineteen new eunicellin diterpenoids named klyflaccilins B-T were isolated from the gorgonian Klyxum flaccidum. The structures were elucidated by NMR, showing that they represent different eunicellin subclasses. For five compounds X-ray crystal structures were obtained that allowed to determine their absolute configurations.

Full Papers

Open Access

Strengths of Acids in Acetonitrile

  • Pages: 1407-1419
  • First Published: 27 January 2021

Description unavailable

Revised pKa scale, containing 231 acids and spanning almost 30 orders of magnitude of acidities in acetonitrile, one of the most useful solvents for non-aqueous acid-base chemistry, is presented.

Communications

Copper-Catalyzed Three-Component Reactions of 2-Iodo-2,2-difluoroacetophenones, Alkynes, and Trimethylsilyl Cyanide

  • Pages: 1420-1423
  • First Published: 18 January 2021
Description unavailable

A Cu(I)-catalyzed three-component reaction of 2-iodo-2,2-difluoroacetophenones, alkynes, and TMSCN for the synthesis of useful difluoroacyl-substituted nitriles is described. This method has broad substrate scope and excellent stereoselectivity. Preliminary mechanistic investigation indicated that a radical-mediated process was involved in this cyanodifluoroalkylation reaction.

Nickel-Catalyzed Regioselective Arylboration of Conjugated Dienes

  • Pages: 1424-1428
  • First Published: 05 February 2021
Description unavailable

The nickel-catalyzed arylboration reactions of conjugated dienes were demonstrated. These reactions proceed under mild reaction conditions with good regio- and stereoselectivity and wide functional group compatibility. Both the reactivity and selectivity are attributed to the use of nitrogen-based ligands. This method provides an approach to allyl and homoallyl boronic ester derivatives starting from 1,3-dienes, aryl bromides, and B2pin2.

Full Papers

Synthesis, Radiosynthesis, and in vitro Studies on Novel Hypoxia PET Tracers Incorporating [18F]FDR

  • Pages: 1429-1439
  • First Published: 09 February 2021
Description unavailable

The synthesis of five radiotracers incorporating different oxyamine spacers between the hypoxia-reactive 2-nitroimidazole moiety and the [18F]FDR (2-fluorodeoxyribose) prosthetic group is described. The lead compound – carrying a cyclopropyl spacer – displayed superior uptake kinetics and similar selectivity for hypoxic cells relative to the gold standard hypoxia tracers [18F]FAZA and [18F]FMISO.

Communications

Triptycene Boronates, Boranes, and Boron Ate-Complexes: Toward Sterically Hindered Triarylboranes and Trifluoroborates

  • Pages: 1440-1445
  • First Published: 03 February 2021
Description unavailable

Borylated triptycene building blocks: bulky boronates, boranes, and organotrifluoroborates derived from triptycenes were prepared via two different synthetic pathways. A systematic structural investigation was performed to evaluate the structure of these unprecedented B−C(sp2) and B−C(sp3) boron derivatives connected to the bulkyl triptycene scaffold.

Full Papers

Methylthiolation for Electron-Rich Heteroarenes with DMSO-TsCl

  • Pages: 1446-1451
  • First Published: 04 February 2021
Description unavailable

DMSO-TsCl is developed for methylthiolation of various heteroarenes including pyrroles, furans, thiophenes and indoles under facile conditions. This protocol features scalable, general applicability of substrates and moderate to excellent yields. An acceptable mechanism is proposed, two of the key intermediates of proposed mechanism are detected by HRMS. Further applications of this method were also conducted.

Open Access

Synthesis and Liquid Crystalline Self-Assembly of Concave Diindoles with a Hydropentalene Core

  • Pages: 1452-1465
  • First Published: 29 January 2021
Description unavailable

The indole-containing concave-shaped calamitic liquid crystals, accessible from Weiss diketone and bromophenylhydrazine in three steps involving Fischer indole, N-protection, and Suzuki cross-coupling, formed N and SmA mesophases whose range and type depended on the substituent R.

Iron-Catalyzed Electrophilic Amination of Sodium Sulfinates with Anthranils

  • Pages: 1466-1473
  • First Published: 02 February 2021
Description unavailable

An iron-catalyzed electrophilic amination of sodium sulfinates with anthranils to generate N-(2-carbonylaryl) benzenesulfonamides with high atom efficiency under redox-neutral conditions has been developed.