• Issue
    Volume 2020, Issue 42
    6501-6672
    November 15, 2020

Cover Picture

Free Access

Front Cover: Reductive Carbon–Carbon Bond Forming Reactions with Carbonyls Mediated by Rh–H Complexes (Eur. J. Org. Chem. 42/2020)

  • Pages: 6501
  • First Published: 30 October 2020
Description unavailable

The Front Cover shows an effective synthetic method of a cholesterol absorption inhibitor, ezetimibe, by reductive Mannich reaction using a rhodium-hydride complex. The back-ground picture is the Japanese rock garden “karesansui” at Ryōan-ji Temple in Kyoto (Japan). Karesansui expresses the spirit of “Wabi-Sabi” that is meaning to discover new radiance (as various C–C bond formations) by reducing any wasteful and useless things. More information can be found in the Minireview by K. Sato, M. Omote et al.

Free Access

Cover Feature: Tetraaryl Cyclopentadienones: Experimental and Theoretical Insights into Negative Solvatochromism and Electrochemistry (Eur. J. Org. Chem. 42/2020)

  • Pages: 6502
  • First Published: 04 November 2020
Description unavailable

The Cover Feature shows the legendary Ulm Sparrow (Ulmer Spatz) carrying the title molecule through the Ulm town gate. According to legend, the people of Ulm learned how to carry long loads through the gate by watching the sparrow carry a straw lengthwise through a small opening. In our illustration, the absorption properties of the title molecules are altered depending on the type of solvent (represented by the gate). The molecular absorption spectra mirror the shape of Ulm Minster, which is the town's landmark and the tallest church spire in the world. We thank Jannik Brückmann for the illustration. More information can be found in the Full Paper by D. Nauroozi et al.

Minireviews

C–C bond formation | Very Important Paper

Reductive Carbon–Carbon Bond Forming Reactions with Carbonyls Mediated by Rh–H Complexes

  • Pages: 6503-6511
  • First Published: 20 August 2020
Description unavailable

Reductive carbon–carbon bond forming reaction of α,β-unsaturated carbonyls is a preferable method to insert electrophiles at α-position of carbonyl group, regioselectively. In this minireview, we summarized our works related to Rh-catalyzed reductive aldol reaction, reductive Mannich reaction, and reductive α-acylation together with recent aspects of metal catalyzed reductive C–C bond formations.

Asymmetric Catalysis

Open Access

Applications of Chiral Cyclopentadienyl (Cpx) Metal Complexes in Asymmetric Catalysis

  • Pages: 6512-6524
  • First Published: 21 July 2020
Description unavailable

In the last two decades significant progress in enantioselective transformations employing chiral Cp ligands (Cpx) has been made. The use of these ligands has typically been associated with Group 9 metals (Co, Rh, Ir), however the use of chiral Cpx ligands has also been reported in combination with early transition-metals and rare-earth elements. This minireview presents an overview of the recent asymmetric reactions that have been successfully steered with chiral Cpx metal complexes. The reactions are discussed according to the metal coordinated by the ligand.

Review

MultiComponent Reactions

The Ugi Three-Component Reaction; a Valuable Tool in Modern Organic Synthesis

  • Pages: 6525-6554
  • First Published: 30 September 2020
Description unavailable

Sixty years after its discovery, the Ugi three component reaction is still relevant today. A comprehensive review article on the reaction is reported with a special focus on its scope and limitations, post-modifications, 3D solid conformations, and applications in drug discovery and materials science.

Full Papers

Tetraaryl Cyclopentadienones

Open Access

Tetraaryl Cyclopentadienones: Experimental and Theoretical Insights into Negative Solvatochromism and Electrochemistry

  • Pages: 6555-6562
  • First Published: 26 August 2020
Description unavailable

Substitution at tetraaryl cyclopentadienones is known to affect the photophysical properties of the molecules. In a joint experimental and theoretical investigation, a series of differently substituted tetraaryl cyclopentadienones are studied upon so far unprecedented negative solvatochromic effect and, the impact of substituents on the electrochemical behavior.

Communications

Heterocycles

Synthesis of Spiro[benzofuran-2,2'-benzo[b]thiophene]-3,3'-diones via PIDA/CuBr-Mediated Spirocyclization

  • Pages: 6563-6569
  • First Published: 15 October 2020
Description unavailable

A phenyliodine(III) diacetate (PIDA)/CuBr-mediated construction of the novel 3H,3'H-spiro[benzofuran-2,2'-benzo[b]thiophene]-3,3'-dione skeleton was realized from the reaction of (Z)-3-hydroxy-1-(2-hydroxyphenyl)-3-(2-halogenphenyl)prop-2-en-1-ones with potassium ethylxanthate in the presence of 1,10-phen. The reaction sequence was postulated to encompass a PIDA-mediated oxidative C–O bond formation followed by a CuBr-mediated spirocyclization step.

Resorcinarenes

Open Access

DISTAL Dibromoresorcin[4]arenes Through Selective Deactivation: A Practical Optimization

  • Pages: 6570-6575
  • First Published: 04 November 2020
Description unavailable

Distal disubstituted resorcinarenes serve as precursors for cavitands and hemicarcerands. Yet the lack of high yield syntheses and their challenging isolation often limit their application. We present a straightforward access, utilizing selective SEAr deactivation for early-stage product determination, making complex isolation methods obsolete. Product limiting factors were overcome by starting material recovery and workup-considered syntheses.

Full Papers

Halogen-Dance

Open Access

Evidence for “Halogen-Dance” and Ring-Exchange Reactions in Chloro-methylthio-ferrocenes

  • Pages: 6576-6587
  • First Published: 24 September 2020
Description unavailable

Deprotonation of pentachloroferrocenes [C5Cl5]Fe[C5H4X] (X = H, Br, SMe) and quench with MeSSMe produces complex product mixtures, which include compounds with [C5Cl4(SMe)] ligands or compounds which contained six or more chlorine atoms. The occurrence of such products can only be explained by halogen-dance and/or cyclopentadienyl ring exchange reactions. Herein, some of the key compounds could be characterized by X-ray diffraction.

Reviews

Diazabicyclic Olefins

Diazanorbornene: A Valuable Synthon towards Carbocycles and Heterocycles

  • Pages: 6588-6613
  • First Published: 29 September 2020
Description unavailable

The present review summarizes the recent progress on desymmetrization of diazanorbornenes towards substituted/fused cyclopentanoids through catalyzed or uncatalyzed pathways.

Full Papers

Organocatalysis

Stereo- and Regioselective Construction of Spirooxindoles Having Continuous Spiral Rings via Asymmetric [3+2] Cyclization of 3-Isothiocyanato Oxindoles with Thioaurone Derivatives

  • Pages: 6614-6622
  • First Published: 08 October 2020
Description unavailable

A highly efficient enantioselective [3+2] cyclization of 3-isothiocyanato oxindoles with thioaurone derivatives was developed for the synthesis of spirooxindoles containing continuous spiral ring structures.

Communications

Asymmetric Synthesis of Diazaspiro[4.5]decadienones

Organocatalytic Asymmetric Formal [3+3]-Cycloaddition to Access 2,3-Diazaspiro[4.5]deca-3,6-dien-1-ones

  • Pages: 6623-6628
  • First Published: 03 September 2020
Description unavailable

Single structure out of many domino reactions! Double sequence of isoaromatization and dearomatization driven the domino Michael/aldol or formal [3+3]-cycloaddition as an efficient tool for the construction of chiral drug-like 2,3-diazaspiro[4.5]deca-3,6-dien-1-ones having spirocyclic vicinal quaternary carbon centers.

Cascade Reaction

Open Access

Gold(I)-Catalyzed Allene–Diene–Alkyne Coupling Reaction to Polycycles

  • Pages: 6629-6634
  • First Published: 22 September 2020
Description unavailable

Five C–C bonds in one step – the gold(I)-catalyzed reaction of aryloxy-substituted haloacetylenes with aryl alkynes leads, through dearomatization reaction and allene–diene–alkyne coupling, to polycyclic compounds.

Full Papers

Iron Catalysis

Catalytic Selective Oxidation of Primary and Secondary Alcohols Using Nonheme [Iron(III)(Pyridine-Containing Ligand)] Complexes

  • Pages: 6635-6644
  • First Published: 28 September 2020
Description unavailable

Selective oxidation of several primary and secondary alcohols to carbonyl compounds by hydrogen peroxide are performed with [Fe(III)(Pc-L)] catalysts (Pc-L = pyridine-based 12-membered tetraaza-macrocyclic ligands) in the absence of any additive. Preliminary mechanistic studies are in agreement with a catalytic cycle promoted by a high-spin iron complex.

Communications

Carbasugars

Open Access

Optimized and Scalable Synthesis of Carba-α-d-Glucosamine

  • Pages: 6645-6648
  • First Published: 29 September 2020
Description unavailable

A scalable route to carba-α-d-glucosamine involves a stereoconvergent Ferrier rearrangement of hindered substrates in combination with a uniform protective group strategy and will enable more detailed biological studies of the unique mode of action of this potent novel antibiotic.

Nucleophilic Aromatic Substitutions

Chemoselective Arylation of Dialkyl Diselenides and Application to the Synthesis of a ε-N,N,N-Trimethyllysine Derivative

  • Pages: 6649-6652
  • First Published: 28 September 2020
Description unavailable

Chemoselective SNAr reactions of dialkyl diselenides proceeded by the combined use of 2,4-dinitrobromobenzene and NaBH4 in the presence of an amine, a thiol, and a carboxylic acid. A ε-N,N,N-trimethyllysine derivative was synthesized from a selenohomocysteine derivative by using the SNAr reaction as a key step, followed by oxidation, olefin metathesis with 4-iodobutene, reduction, and substitution with trimethylamine.

Photocatalyzed Sulfonylation

Three-Component C–H Bond Sulfonylation of Imidazoheterocycles by Visible-Light Organophotoredox Catalysis

  • Pages: 6653-6660
  • First Published: 14 October 2020
Description unavailable

The first examples of visible-light induced direct sulfur dioxide insertion on imidazoheterocycles have been developed using an organic photoredox catalyst at room temperature and DABCO·(SO2)2. The formation of 2 new C–S bonds, without further pre-functionalization, in metal-free and mild conditions render this three-component approach sustainable and green and led to novel and valuable C-3 sulfonylated imidazoheterocycles in moderate to good yields.

Full Papers

Total Synthesis

Isobenzofurans as Synthetic Intermediates: Synthesis and Biological Activity of 8-epi-(–)-Ajudazol B

  • Pages: 6661-6672
  • First Published: 15 September 2020
Description unavailable

The step-economic convergent total synthesis of 8-epi-(–)-ajudazol B has been achieved taking advantage of isobenzofuran as synthetic intermediates. This approach proves the synthetic utility of isobenzofurans as reactive intermediates and provides a fast and efficient way to generate ajudazol analogues with anti-fungal activity through minimal manipulation.