scholarly journals Dichlorodioxomolybdenum(VI) Complexes: Useful and Readily Available Catalysts in Organic Synthesis

Synthesis ◽  
2018 ◽  
Vol 50 (20) ◽  
pp. 4019-4036 ◽  
Author(s):  
Roberto Sanz ◽  
Raquel Hernández-Ruiz
Keyword(s):  
Transition Metal Complexes ◽  
Lewis Acid ◽  
Short Review ◽  
Lewis Base ◽  
Phosphorus Compounds ◽  
Oxidation Reactions ◽  
Organic Transformations ◽  
Reduction Reactions ◽  
Acid Type ◽  
Catalyzed Reactions

Molybdenum(VI) dichloride dioxide (MoO2Cl2), and its addition complexes [MoO2Cl2(L)n; L = neutral ligand], are commercially or easily available and inexpensive transition-metal complexes based on a non-noble metal that can be applied as catalysts for various organic transformations. This short review aims to present the most significant breakthroughs in this field.1 Introduction2 Preparation and Reactivity of MoO2Cl2(L)n Complexes2.1 Synthesis and Structure2.2 Reactivity of Dichlorodioxomolybdenum(VI) Complexes3 Redox Processes Catalyzed by MoO2Cl2(L)n Complexes3.1 Deoxygenation Reactions Using Phosphorus Compounds3.2 Deoxygenation and Hydrosilylation Reactions Using Silanes3.3 Reduction Reactions Using Hydrogen3.4 Deoxygenation Reactions with Boranes and Thiols3.5 Reduction Reactions with Glycols3.6 Oxidation Reactions4 Ambiphilic Reactivity of MoO2Cl2 4.1 Amphoteric Lewis Acid–Lewis Base Catalyzed Reactions4.2 Lewis Acid Type Catalyzed Reactions5 Conclusion and Perspective

Unconventional Transformations of Morita–Baylis–Hillman Adducts

Synthesis ◽  
2020 ◽  
Author(s):  
Xavier Companyó ◽  
Alessio Calcatelli ◽  
Alessio Cherubini-Celli ◽  
Edoardo Carletti
Keyword(s):  
Transition Metal Complexes ◽  
Short Review ◽  
Lewis Base ◽  
Base Catalysis ◽  
Allylic Alkylation ◽  
One Pot ◽  
Allylic Alkylations ◽  
Cascade Processes ◽  
Dual Activation ◽  
Trisubstituted Alkenes

Morita–Baylis–Hillman (MBH) adducts are versatile starting materials widely employed in Lewis base catalysis. A myriad of different transformations have been reported based on either allylic alkylations with stabilised nucleophiles or annulations with diverse dipolarophiles. Apart from these two conventional types of reactivity, MBH adducts have recently been implemented in alternative and complementary catalytic strategies, including: (i) one-pot and cascade transformations, where additional chemical bonds are formed following the asymmetric allylic alkylation event in a single synthetic operation; (ii) regioselective α-allylations for the synthesis of trisubstituted alkenes; and (iii) dual activation strategies, involving Lewis base catalysis together with transition metal complexes or light, enabling allylic alkylations with nonstabilised nucleophiles and cascade processes. The present Short Review summarises the most significant unconventional catalytic transformations of racemic MBH adducts reported within the last decade.1 Introduction2 Multi-Step Single-Vessel Transformations (path iii)2.1 One-Pot Transformations2.2 Cascade Transformations3 α-Allylations (path iv)3.1 SN2′ Mechanism3.2 SN2′–SN2 Mechanism3.3 Miscellaneous Mechanisms4 Dual Activation (path v)4.1 MBH Adduct as Electrophile4.2 MBH Adduct as Nucleophile5 Summary and Outlook

scholarly journals Recent Advances in Water-Tolerance in Frustrated Lewis Pair Chemistry

Synthesis ◽  
2018 ◽  
Vol 50 (09) ◽  
pp. 1783-1795 ◽  
Author(s):  
Michael Ingleson ◽  
Valerio Fasano
Keyword(s):  
Small Molecules ◽  
Lewis Acid ◽  
Lewis Acids ◽  
Short Review ◽  
Lewis Base ◽  
Small Molecule Activation ◽  
Significant Progress ◽  
Water Tolerance ◽  
Frustrated Lewis Pair ◽  
Main Challenge

A water-tolerant frustrated Lewis pair (FLP) combines a sterically encumbered Lewis acid and Lewis base that in synergy are able to activate small molecules even in the presence of water. The main challenge introduced by water comes from its reversible coordination to the Lewis acid which causes a marked increase in the Brønsted acidity of water. Indeed, the oxophilic Lewis acids typically used in FLP chemistry form water adducts whose acidity can be comparable to that of strong Brønsted acids such as HCl, thus they can protonate the Lewis base component of the FLP. Irreversible proton transfer quenches the reactivity of both the Lewis acid and the Lewis base, precluding small molecule activation. This short review discusses the efforts to overcome water-intolerance in FLP systems, a topic that in less than five years has seen significant progress.1 Introduction2 Water-Tolerance (or Alcohol-Tolerance) in Carbonyl Reductions3 Water-Tolerance with Stronger Bases4 Water-Tolerant Non-Boron-Based Lewis Acids in FLP Chemistry5 Conclusions

Organocatalysis: An overview on its application in oxidation and reduction reactions

2021 ◽  
Vol 08 ◽  
Author(s):  
Rammyani Pal ◽  
Chhanda Mukhopadhyay
Keyword(s):  
Organic Synthesis ◽  
Organic Molecules ◽  
Aldol Condensation ◽  
Oxidation Reactions ◽  
Reaction Conditions ◽  
Catalytic Systems ◽  
Reduction Reactions ◽  
Elementary Reactions ◽  
Catalyzed Reactions ◽  
Complex Organic

: Organocatalysis has been established to be a wide-applicable approach from its inception and rediscovery in 2000. Proline was used as a catalyst in aldol condensation and soon after the successful emergence of iminium catalyzed reactions in organic synthesis. The development of new potential catalytic systems is always an essential and uphill task for scientists and researchers. The fundamental organic synthesis majorly deals with metal-based catalysts, whereas there is a constant surge of developing metal-free reaction conditions to make the reactions environmental friendly. For the synthesis of complex organic molecules, reduction and oxidation reactions are always needed, and there are plenty of catalysts available for these reactions. Organocatalysts are also developed and applied for these two elementary reactions. This review focuses on some of the latest developments and applications of organocatalystsin oxidation and reduction reactions in fundamental organic synthesis.

The Synthesis and Application of Functionalized Mesoporous Silica SBA-15 as Heterogeneous Catalyst in Organic Synthesis

2020 ◽  
Vol 24 ◽  
Author(s):  
Ghodsi Mohammadi Ziarani ◽  
Shima Roshankar ◽  
Fatemeh Mohajer ◽  
Alireza Badiei
Keyword(s):  
Mesoporous Silica ◽  
Heterogeneous Catalyst ◽  
Organic Synthesis ◽  
Lewis Acid ◽  
Heterogeneous Catalysts ◽  
Organic Transformations ◽  
Functionalized Mesoporous Silica ◽  
Silica Nanomaterials ◽  
Wide Range ◽  
Target Molecules

Abstract:: Mesoporous silica nanomaterials provide an extraordinary advantage for making new and superior heterogeneous catalysts because of their surface silanol groups. The functionalized mesoporous SBA-15, such as acidic, basic, BrÖnsted, lewis acid, and chiral catalysts, are used for a wide range of organic synthesis. The importance of the chiral ligands, which were immobilized on the SBA-15, was mentioned in this review to achieve chiral products as valuable target molecules. Herein, their synthesis and application in different organic transformations are reviewed from 2016 till date 2020.

Metal Doped-C3N4/Fe2O4: Efficient and Versatile Heterogenous Catalysts for Organic Transformations

2019 ◽  
Vol 23 (12) ◽  
pp. 1284-1306
Author(s):  
Vijai K. Rai ◽  
Fooleswar Verma ◽  
Suhasini Mahata ◽  
Smita R. Bhardiya ◽  
Manorama Singh ◽  
...  
Keyword(s):  
Ring Opening ◽  
Carbon Nitride ◽  
Addition Reaction ◽  
High Surface ◽  
Graphitic Carbon ◽  
Graphitic Carbon Nitride ◽  
Organic Transformations ◽  
Reduction Reactions ◽  
Activation Reaction ◽  
Metal Doped

The polymeric graphitic carbon nitride (g-C3N4) has been one of the interesting earth abundant elements. Though g-C3N4 finds application as a photocatalyst, its photocatalytic behaviour is limited because of low efficiency, mainly due to rapid charge recombination. To overcome this problem, several strategies have been developed including doping of metal/non-metal in the cavity of g-C3N4. Moreover, the CoFe2O4 NPs have been used in many organic transformations because of its high surface area and easy separation due to its magnetic nature. This review describes the role of cobalt ferrite as magnetic nanoparticles and metal-doped carbon nitride as efficient heterogeneous catalysts for new carbon-carbon and carbon-hetero atom bond formation followed by heterocyclization. Reactions which involved new catalysts for selective activation of readily available substrates has been reported herein. Since nanoparticles enhance the reactivity of catalyst due to higher catalytic area, they have been employed in various reactions such as addition reaction, C-H activation reaction, coupling reaction, cyclo-addition reaction, multi-component reaction, ring-opening reaction, oxidation reaction and reduction reactions etc. The driving force for choosing this topic is based-on huge number of good publications including different types of spinels/metal doped-/graphitic carbon nitride reported in the literature and due to interest of synthetic community in recent years. This review certainly will represent the present status in organic transformation and for exploring further their catalytic efficiency to new organic transformations involving C-H activation reaction through coupling, cyclo-addition, multi-component, ring-opening, oxidation and reduction reactions.

Chemistry of Unsymmetrical C1-Substituted Oxabenzonorbornadienes

2021 ◽  
Vol 17 ◽  
Author(s):  
Austin Pounder ◽  
Angel Ho ◽  
Matthew Macleod ◽  
William Tam
Keyword(s):  
Transition Metal ◽  
Metal Complexes ◽  
Transition Metal Complexes ◽  
Substituent Effects ◽  
Face Selectivity ◽  
Transition Metal Catalyzed ◽  
Catalyzed Reactions ◽  
Metal Catalyzed ◽  
Synthetic Intermediate

: Oxabenzonorbornadiene (OBD) is a useful synthetic intermediate which can be readily activated by transition metal complexes with great face selectivity due to its dual-faced nature and intrinsic angle strain on the alkene. To date, the understanding of transition-metal catalyzed reactions of OBD itself has burgeoned; however, this has not been the case for unsymmetrical OBDs. Throughout the development of these reactions, the nature of C1-substituent has proven to have a profound effect on both the reactivity and selectivity of the outcome of the reaction. Upon substitution, different modes of reactivity arise, contributing to the possibility of multiple stereo-, regio-, and in extreme cases, constitutional isomers which can provide unique means of constructing a variety of synthetically useful cyclic frameworks. To maximize selectivity, an understanding of bridgehead substituent effects is crucial. To that end, this review outlines hitherto reported examples of bridgehead substituent effects on the chemistry of unsymmetrical C1-substituted OBDs.

scholarly journals Frustration across the periodic table: heterolytic cleavage of dihydrogen by metal complexes

2017 ◽  
Vol 375 (2101) ◽  
pp. 20170002 ◽  
Author(s):  
R. Morris Bullock ◽  
Geoffrey M. Chambers
Keyword(s):  
Transition Metal ◽  
Metal Complexes ◽  
Transition Metal Complexes ◽  
Molecular Complexes ◽  
Main Group ◽  
Lewis Base ◽  
Metal Compounds ◽  
Metal Catalysis ◽  
Heterolytic Cleavage ◽  
Lewis Pairs

This perspective examines frustrated Lewis pairs (FLPs) in the context of heterolytic cleavage of H 2 by transition metal complexes, with an emphasis on molecular complexes bearing an intramolecular Lewis base. FLPs have traditionally been associated with main group compounds, yet many reactions of transition metal complexes support a broader classification of FLPs that includes certain types of transition metal complexes with reactivity resembling main group-based FLPs. This article surveys transition metal complexes that heterolytically cleave H 2 , which vary in the degree that the Lewis pairs within these systems interact. Many of the examples include complexes bearing a pendant amine functioning as the base with the metal functioning as the hydride acceptor. Consideration of transition metal compounds in the context of FLPs can inspire new innovations and improvements in transition metal catalysis. This article is part of the themed issue ‘Frustrated Lewis pair chemistry’.

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