Asymmetric tandem reactions: New synthetic strategies

2010 ◽  
Vol 82 (3) ◽  
pp. 669-677 ◽  
Author(s):  
Santos Fustero ◽  
María Sánchez-Roselló ◽  
Carlos del Pozo
Keyword(s):  
Nucleophilic Addition ◽  
Multicomponent Reactions ◽  
Tandem Reactions ◽  
Aromatic Substitution ◽  
Atom Economy ◽  
Complex Molecules ◽  
Cross Metathesis ◽  
Carbonyl Derivatives ◽  
Synthetic Sequence ◽  
First Time

The use of domino and multicomponent reactions in asymmetric synthesis is constantly increasing nowadays. This allows for the synthesis of complex molecules in a single synthetic sequence, usually with high atom economy. Herein, we report three examples of new asymmetric tandem reactions recently developed in our laboratories, giving rise to new families of enantiomerically enriched fluorinated and nonfluorinated heterocycles. Thus, 1,4-dihydropyridines (1,4-DHPs) bearing fluorinated substituents at C6 were assembled by means of a Hantzsch-type reaction; cyclic β-amino carbonyl derivatives were prepared using a cross-metathesis (CM)–intramolecular aza-Michael sequence; while fluorinated indolines were obtained, for the first time, in a tandem nucleophilic addition–intramolecular aromatic substitution.

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

2018 ◽  
Vol 14 ◽  
pp. 1508-1528 ◽  
Author(s):  
Gwendal Grelier ◽  
Benjamin Darses ◽  
Philippe Dauban
Keyword(s):  
Nucleophilic Addition ◽  
Coupling Reaction ◽  
Building Blocks ◽  
Tandem Reactions ◽  
Atom Economy ◽  
One Pot

Most of the polyvalent organoiodine compounds derive from iodoarenes, which are released in stoichiometric amounts in any reaction mediated by λ3- or λ5-iodanes. In parallel to the development of solid-supported reagents or reactions catalytic in iodine, a third strategy has emerged to address this issue in terms of sustainability. The atom-economy of transformations involving stoichiometric amounts of λ3- or λ5-iodanes, thus, has been improved by designing tandem reactions that allows for incorporating the aryl motif into the products through a subsequent one-pot nucleophilic addition or catalytic coupling reaction. This review summarizes the main achievements reported in this area.

Design, synthesis and evaluation of structurally diverse ortho-acylphenol-diindolylmethane hybrids as anticancer agents

2022 ◽  
Author(s):  
Zhi-Gang Yin ◽  
Xiong-Wei Liu ◽  
Hui-Juan Wang ◽  
Min Zhang ◽  
Xiong-Li Liu ◽  
...  
Keyword(s):  
Carboxylic Acid ◽  
Anticancer Agents ◽  
Nucleophilic Addition ◽  
Ring Opening ◽  
Building Blocks ◽  
Efficient Synthesis ◽  
Design Synthesis ◽  
Pyrone Ring ◽  
Ring Opening Reaction ◽  
First Time

A highly efficient synthesis of structurally diverse ortho-acylphenol–diindolylmethane hybrids 3 using carboxylic acid-activated chromones as versatile synthetic building blocks is reported here for the first time, through 1,4-nucleophilic addition and followed by a decarboxylation and pyrone ring opening reaction process.

scholarly journals One pot synthesis of 3, 4-dihydropyrimidine-2(1H)-thiones using orange peel powder under ultrasonic irradiation

2020 ◽  
Vol 9 (1) ◽  
pp. 919-923
Keyword(s):  
Reaction Time ◽  
Ultrasonic Irradiation ◽  
Heterocyclic Compounds ◽  
Multicomponent Reactions ◽  
Orange Peel ◽  
Biologically Active ◽  
High Yield ◽  
Atom Economy ◽  
One Pot ◽  
The Past

Biginelli, an important multicomponent reaction provides an avenue for the synthesis of different biologically active heterocyclic compounds. During the past decade, one pot multicomponent reactions have attracted the attention of organic and medicinal chemists due to high atom economy, time and enery saving convergent nature. The present manuscript reports a simple one pot three component synthesis of 3, 4-dihydroprimidin-2(1H)-thiones from various diversely substituted aldehydes, ethyl acetoacetate and thiourea using a orange peel powder as a natural catalyst on ultrasonic irradiation in aqueous medium as the solvent. The advantages of this reaction are less reaction time, high yield, easy availability of the catalyst and green nature.

Synthesis of 4-arylethyl-6-arylpyrimidine-2-thiols through aza-Michael addition/nucleophilic addition/aromatization tandem reactions

2018 ◽  
Vol 24 (1) ◽  
pp. 23-26
Author(s):  
Zheng Li ◽  
Wenli Song ◽  
Jiaojiao He ◽  
Yan Du ◽  
Jingya Yang
Keyword(s):  
Efficient Method ◽  
Michael Addition ◽  
Nucleophilic Addition ◽  
Tandem Reactions ◽  
Reaction Conditions ◽  
High Yields ◽  
Work Up

Abstract An efficient method for the synthesis of the title compounds by reactions of divinyl ketones with thiourea is described. This protocol has the advantages of high yields, mild reaction conditions and simple work-up procedure.

Nucleophilic substitution of meso-nitrooctaethylporphyrins

1985 ◽  
Vol 63 (2) ◽  
pp. 406-411 ◽  
Author(s):  
Liang-Chu Gong ◽  
David Dolphin
Keyword(s):  
Nucleophilic Substitution ◽  
Nucleophilic Addition ◽  
Nucleophilic Aromatic Substitution ◽  
Redox Potentials ◽  
Aromatic Substitution ◽  
Halogen Atoms

Nitrooctaethylporphyrins readily undergo nucleophilic aromatic substitution in the presence of HCl or HBr. In the presence of methoxide, nucleophilic addition to give a porphodimethane occurs, followed by autoxidation to the methoxyporphyrin. Unlike the nitrated complexes, the chlorosubstituted porphyrins exhibit redox potentials similar to those of unsubstituted analogs. Meso-halogenated porphyrins do, however, show steric distortion due to the bulk of the halogen atoms.

scholarly journals The ALMA-PILS Survey: Formaldehyde deuteration in warm gas on small scales toward IRAS 16293–2422 B

2018 ◽  
Vol 610 ◽  
pp. A54 ◽  
Author(s):  
M. V. Persson ◽  
J. K. Jørgensen ◽  
H. S. P. Müller ◽  
A. Coutens ◽  
E. F. van Dishoeck ◽  
...  
Keyword(s):  
Energy Levels ◽  
Excitation Temperature ◽  
Thermodynamical Equilibrium ◽  
Complex Molecules ◽  
Important Species ◽  
Chemical Models ◽  
Small Scales ◽  
Core Phase ◽  
Low Mass ◽  
First Time

Context.The enhanced degrees of deuterium fractionation observed in envelopes around protostars demonstrate the importance of chemistry at low temperatures, relevant in pre- and protostellar cores. Formaldehyde is an important species in the formation of methanol and more complex molecules.Aims.Here, we aim to present the first study of formaldehyde deuteration on small scales around the prototypical low-mass protostar IRAS 16293–2422 using high spatial and spectral resolution Atacama Large Millimeter/submillimeter Array (ALMA) observations. We determine the excitation temperature, abundances and fractionation level of several formaldehyde isotopologues, including its deuterated forms.Methods.Excitation temperature and column densities of formaldehyde in the gas close to one of the components of the binary were constrained through modeling of optically thin lines assuming local thermodynamical equilibrium. The abundance ratios were compared to results from previous single dish observations, astrochemical models and local ISM values.Results.Numerous isotopologues of formaldehyde are detected, among them H2C17O, and D213CO for the first time in the ISM. The large range of upper energy levels covered by the HDCO lines help constrain the excitation temperature to 106 ± 13 K. Using the derived column densities, formaldehyde shows a deuterium fractionation of HDCO/H2CO = 6.5 ± 1%, D2CO/HDCO = 12.8–4.1+3.3%, and D2CO/H2CO = 0.6(4) ± 0.1%. The isotopic ratios derived are16O/18O = 805–79+43,18O/17O = 3.2–0.3+0.2, and12C/13C = 56–11+8.Conclusions.The HDCO/H2CO ratio is lower than that found in previous studies, highlighting the uncertainties involved in interpreting single dish observations of the inner warm regions. The D2CO/HDCO ratio is only slightly larger than the HDCO/H2CO ratio. This is consistent with formaldehyde forming in the ice as soon as CO has frozen onto the grains, with most of the deuteration happening toward the end of the prestellar core phase. A comparison with available time-dependent chemical models indicates that the source is in the early Class 0 stage.

Isocyanide and Meldrum's acid-based multicomponent reactions in diversity-oriented synthesis: from a serendipitous discovery towards valuable synthetic approaches

RSC Advances ◽  
2016 ◽  
Vol 6 (63) ◽  
pp. 58142-58159 ◽  
Author(s):  
Ahmad Shaabani ◽  
Seyyed Emad Hooshmand
Keyword(s):  
Multicomponent Reactions ◽  
Molecular Diversity ◽  
Single Step ◽  
Atom Economy ◽  
Meldrum's Acid ◽  
Meldrum’S Acid ◽  
Diversity Oriented Synthesis ◽  
Synthetic Approaches

Multicomponent reactions, which lead to synthesis of target compounds with inherent molecular diversity, greater efficiency and atom economy, are single step types of reactions made from three or more reactants attract the attention of all chemists.

Mechanisms and models for homogeneous copper mediated ligand exchange reactions of the type: CuNu + ArX → ArNu + CuX

1985 ◽  
Vol 63 (1) ◽  
pp. 111-120 ◽  
Author(s):  
Christiane Couture ◽  
Anthony James Paine
Keyword(s):  
Molecular Design ◽  
Nucleophilic Aromatic Substitution ◽  
Common Mechanism ◽  
Aromatic Substitution ◽  
Exchange Reactions ◽  
Design And Synthesis ◽  
Alkyl Groups ◽  
Leaving Group ◽  
First Time ◽  
Redox Equilibria

The title reactions are an important class of copper mediated nucleophilic aromatic substitution processes, which constitute a useful tool in the molecular design and synthesis of small molecules. We report the results of extensive investigation of these processes, primarily focussing on cyanodeiodination (ArI + CuCN → CuI + ArCN). Among the interesting features of these processes are: (a) an unusual rate equation involving autocatalysis by CuI product; (b) retardation by both excess nucleophile (as KCN) and excess leaving group (as KI), which compete with ArX to complex with CuNu; (c) only cuprous nucleophiles are active (ligand exchanged products from cupric salts arise from prior redox equilibria which form CuNu); (d) the halogen effect is large (kI ~ 40–100 kBr ~ 300–5000kCl) but the Hammett ρ value is zero; (e) ortho-alkyl groups do not hinder the reaction (and actually cause mild acceleration by relief of steric strain). Finally, the introduction of an ortho-COO− group accelerates the reaction by a factor of 104–105, but the general features of the accelerated reactions are also the same, again indicating a common mechanism, with entropic acceleration by ortho-carboxylate. Both kinetic and thermodynamic factors were considered in detail, the latter apparently for the first time. Applications to practical syntheses are considered, and novel mechanistic models for these interesting processes are discussed.

scholarly journals Iridium-Catalyzed Asymmetric α-Allylic Alkylation of Amides using Vinyl Azide as Amide Enolate Surrogate

2020 ◽  
Author(s):  
Aditya Chakrabarty ◽  
Santanu Mukherjee
Keyword(s):  
Electronic Properties ◽  
Reaction Pathways ◽  
Allylic Alcohols ◽  
Allylic Alkylation ◽  
Atom Economy ◽  
Asymmetric Allylic Alkylation ◽  
Vinyl Azides ◽  
Alkylation Reactions ◽  
First Time

Among the unstabilized enolates used as nucleophile in iridium-catalyzed asymmetric allylic alkylation reactions, amide enolates are least explored. Vinyl azides are now employed as amide enolate surrogate for the first time in Ir-catalyzed asymmetric allylic alkylation with branched allylic alcohols as the allylic electrophile. Competing reaction pathways are suppressed through systematic tuning of steric and electronic properties of vinyl azide to effect α-allylic alkylation of secondary acetamides with high atom-economy, exclusive branched selectivity and moderate to excellent enantioselectivity.<br>

scholarly journals Synthesis of polysubstituted spiropyrrolidines using 2-acetylfuran, 2-acetylthiophene, and 2-acetylpyrrole

2021 ◽  
Vol 21 (3) ◽  
pp. 254-259
Author(s):  
Svetlana V. Borisova ◽  
◽  
Vitaly V. Sorokin ◽  
Keyword(s):  
13C Nmr Spectroscopy ◽  
Azomethine Ylides ◽  
Dipolar Cycloaddition ◽  
Knoevenagel Reaction ◽  
Atom Economy ◽  
Reaction Conditions ◽  
Stereo Selectivity ◽  
Decarboxylative Condensation ◽  
First Time

A series of novel spirooxindoles have been synthesized through three-component 1,3-dipolar cycloaddition of azomethine ylides generated in situ by the decarboxylative condensation of isatin and sarcosine with the dipolarophile 3-phenyl-1-(heteroaryl -2-yl)prop-2-en-1- one, synthesized by the Knoevenagel reaction using 2-acetylfuran, 2-acetylpyrrole, 2-acetylthiophene and substituted benzaldehydes. These compounds are used for the first time as dipolarophiles. This method has the advantages of mild reaction conditions, high atom economy, excellent yields, and high regio- and stereo-selectivity. The reaction was carried out by mixing equimolar amounts of enone and isatin, as well as a slight excess of sarcosine in isopropyl alcohol when heated to 60–70°C. Among the enones with various heterocyclic substituents, it is most convenient to use compounds containing a pyrrole fragment as dipolarophiles, since the products are obtained in a short amount of time in good yields. The use of enones obtained from 2-acetylthiophene leads to an increase in the reaction time, and from 2-acetylfuran - to a significant resinification of the reaction mixture. The structures of the compounds obtained were proved using a combination of 1H, 13C NMR spectroscopy data, as well as two-dimensional NMR experiments of heteronuclear correlation, HSQC and HMBC. Based on the data obtained, a mechanism for the formation of products has been proposed.

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