scholarly journals Recent Advances in Transition Metal-Catalyzed Reactions of Oxabenzonorbornadiene

2019 ◽  
Vol 16 (4) ◽  
pp. 460-484 ◽  
Author(s):  
Rebecca Boutin ◽  
Samuel Koh ◽  
William Tam
Keyword(s):  
Transition Metal ◽  
Structural Features ◽  
Metal Catalysts ◽  
Single Step ◽  
Transition Metal Catalysts ◽  
Biologically Active ◽  
Transition Metal Catalyzed ◽  
Catalyzed Reactions ◽  
Metal Catalyzed ◽  
Work Done

Background: Oxabenzonorbornadiene (OBD) is a useful synthetic intermediate capable of undergoing multiple types of transformations due to three key structural features: a free alkene, a bridged oxygen atom, and a highly strained ring system. Most notably, ring-opening reactions of OBD using transition metal catalysts and nucleophiles produce multiple stereocenters in a single step. The resulting dihydronaphthalene framework is found in many natural products, which have been shown to be biologically active. Objective: This review will provide an overview of transition metal-catalyzed reactions from the past couple of years including cobalt, copper, iridium, nickel, palladium and rhodium- catalyzed reactions. In addition, the recent derivatization of OBD to cyclopropanated oxabenzonorbornadiene and its reactivity will be discussed. Conclusion: It can be seen from the review, that the work done on this topic has employed the use of many different transition metal catalysts, with many different nucleophiles, to perform various transformations on the OBD molecule. Additionally, depending on the catalyst and ligand used, the stereo and regioselectivity of the product can be controlled, with proposed mechanisms to support the understanding of such reactions. The use of palladium has also generated a cyclopropanated OBD, with reactivity similar to that of OBD. An additional reactive site exists at the distal cyclopropane carbon, giving rise to three types of ring-opened products.

Transition Metal-Catalyzed Reactions of 3-Aza-2-oxabicyclo[2.2.1]hept-5-enes

2018 ◽  
Vol 15 (6) ◽  
pp. 762-780
Author(s):  
Katrina Tait ◽  
William Tam
Keyword(s):  
Transition Metal ◽  
Transition Metals ◽  
Bond Cleavage ◽  
Transition Metal Catalysts ◽  
Biologically Active ◽  
Diverse Range ◽  
Oxabicyclic Alkenes ◽  
Transition Metal Catalyzed ◽  
Catalyzed Reactions ◽  
Metal Catalyzed

Background: Transition metal catalysts are becoming increasingly more important in organic synthesis and are being used to catalyze novel reactions that allow for more efficient synthesis of many pharmaceuticals. Transition metal-catalyzed reactions of 3-aza-2-oxabicyco[2.2.1]hept-5-enes provide efficient synthetic pathways to generate a diverse range of biologically and synthetically useful products. 3-Aza-2- oxabicyclic alkenes undergo three main types of reactions: reductive N-O bond cleavage, C-O bond cleavage, and modification of the alkene component. Objective: The purpose of this review is to summarize and discuss the transition metal-mediated reactions of 3- aza-2-oxabicyclo[2.2.1]hept-5-enes, including the mechanisms of reactions based on the transition metal used, the different stereo- and regiochemical outcomes of reactions with this asymmetrical substrate, and the biological importance of exploring these reactions. Conclusion: It is clear from the review of the topic that a vast amount of work has been done in this area, and transition metals have been used to control the regio- and stereoselective reactions of 3-aza-2-oxabicyclic alkenes to create biologically active and synthetically useful products. The transition metal-catalyzed reactions of 3-aza-2-oxabicyclic alkenes proceed through three general reactions: through cleavage of the N-O bond, cleavage of the C-O bond, and modification of the alkene component. Without the use of transition metals, the substrate would not be activated and these reactions would not be possible. The use of transition metals opens up an array of new reactions that have the ability to create different functional groups with different regio- and stereoselectivities based on the metal and conditions used. The products made through these transition metalcatalyzed reactions can be useful as antibiotics, siderophores, and carbocyclic nucleosides such as noraristeromycin and carbocyclic polyoxin C.

Transition Metal-Catalyzed Reactions of Alkynyl Halides

2019 ◽  
Vol 16 (4) ◽  
pp. 546-582 ◽  
Author(s):  
Dina Petko ◽  
Samuel Koh ◽  
William Tam
Keyword(s):  
Transition Metal ◽  
Transition Metal Catalysts ◽  
Cycloaddition Reactions ◽  
Coupling Reactions ◽  
Silicon Carbon ◽  
Transition Metal Catalyzed ◽  
Catalyzed Reactions ◽  
Metal Catalyzed ◽  
Sonogashira Reactions ◽  
Work Done

Background: Transition metal-catalyzed reactions of alkynyl halides are a versatile means of synthesizing a wide array of products. Their use is of particular interest in cycloaddition reactions and in constructing new carbon-carbon and carbon-heteroatom bonds. Transition metal-catalyzed reactions of alkynyl halides have successfully been used in [4+2], [2+2], [2+2+2] and [3+2] cycloaddition reactions. Many carbon-carbon coupling reactions take advantage of metal-catalyzed reactions of alkynyl halides, including Cadiot-Chodkiewicz, Suzuki-Miyaura, Stille, Kumada-Corriu and Inverse Sonogashira reactions. All the methods of constructing carbon-nitrogen, carbon-oxygen, carbon-phosphorus, carbon-sulfur, carbon-silicon, carbon-selenium and carbon-tellurium bonds employed alkynyl halides. Objective: The purpose of this review is to highlight and summarize research conducted in transition metalcatalyzed reactions of alkynyl halides in recent years. The focus will be placed on cycloaddition and coupling reactions, and their scope and applicability to the synthesis of biologically important and industrially relevant compounds will be discussed. Conclusion: It can be seen from the review that the work done on this topic has employed the use of many different transition metal catalysts to perform various cycloadditions, cyclizations, and couplings using alkynyl halides. The reactions involving alkynyl halides were efficient in generating both carbon-carbon and carbonheteroatom bonds. Proposed mechanisms were included to support the understanding of such reactions. Many of these reactions face retention of the halide moiety, allowing additional functionalization of the products, with some new products being inaccessible using their standard alkyne counterparts.

Directing-Group-Assisted Transition-Metal-Catalyzed Direct C–H Oxidative Annulation of Arenes with Alkynes for Facile Construction of Various Oxygen Heterocycles

Synthesis ◽  
2020 ◽  
Vol 52 (07) ◽  
pp. 993-1006 ◽  
Author(s):  
Guanghua Kuang ◽  
Guangyuan Liu ◽  
Xingxing Zhang ◽  
Naihao Lu ◽  
Yiyuan Peng ◽  
...  
Keyword(s):  
Transition Metal ◽  
Noble Metals ◽  
Metal Catalysts ◽  
Transition Metal Catalysts ◽  
Research Papers ◽  
Recent Advances ◽  
Oxygen Heterocycles ◽  
Directing Group ◽  
Transition Metal Catalyzed ◽  
Metal Catalyzed

The most recent advances in the construction of oxygen heterocycles by the directing-group-assisted transition-metal-catalyzed direct oxidative annulation of arenes with diverse alkynes are summarized in this review. More than 140 recent research papers and many closely related reviews are referenced in this paper. Nine different oxygen heterocycles frameworks are discussed. Several traditional transition-metal catalysts as well as some classical non-noble metals are utilized to promote the annulation. Three plausible controlling models are disclosed to clarify the excellent regioselectivity outcomes achieved in case of unsymmetrical alkyne substrates.1 Introduction2 Coumarins3 I socoumarins and Their Analogues4 2-Pyrones and Their Analogues5 Chromones and Chroman-4-ones6 Chromenes and Isochromenes7 Fused Polycyclic Oxygen Heteroaromatics8 Benzofurans, Dihydrobenzofurans, and Furans9 Phthalides and Benzofuranones10 Benzoxepines11 Conclusion

Cu(I)-Bis(phosphine) Dioxides as catalysts for the Enantioselective α-Arylation of Carbonyl Compounds

Synlett ◽  
2021 ◽  
Author(s):  
Margarita Escudero-Casao ◽  
Giulia Licini ◽  
Manuel Orlandi
Keyword(s):  
Reaction Mechanism ◽  
Transition Metal ◽  
Catalytic System ◽  
Carbonyl Compounds ◽  
Research Area ◽  
Metal Catalysts ◽  
Transition Metal Catalysts ◽  
Transition Metal Catalyzed ◽  
Metal Catalyzed

The transition metal catalyzed α-arylation of carbonyl compounds was first reported by Buchwald and Hartwig in 1997. This transformation has been used and studied extensively over the last two decades. Enantioselective variants were also developed that allow for controlling the product stereochemistry. However, these suffer several limitations in the context of formation of tertiary stereocenters. Presented here is our group’s contribution to this research area. The chiral Cu-bis(phosphine) dioxides catalytic system that we reported allowed accessing the enantioselective α-arylation of ketones that were not suitable for this transformation before in good yields and er up to 97.5:2.5. Preliminary insight and speculation concerning the reaction mechanism involving the unusual pairing of bis(phosphine) dioxides with transition metal catalysts is also given.

Phosphorus-Containing Groups Assisted Transition Metal Catalyzed C-H Activation Reactions

2019 ◽  
Vol 23 (2) ◽  
pp. 103-135 ◽  
Author(s):  
Chun-Ni Zhou ◽  
Zi-Ang Zheng ◽  
George Chang ◽  
Yuan-Chao Xiao ◽  
Yang-Huan Shen ◽  
...  
Keyword(s):  
Transition Metal ◽  
Functional Group ◽  
Metal Catalysts ◽  
Transition Metal Catalysts ◽  
Mechanistic Study ◽  
Recent Advances ◽  
Phosphorus Containing ◽  
Directing Group ◽  
Transition Metal Catalyzed ◽  
Metal Catalyzed

Over the last few decades, transition metal-catalyzed direct C-H activation with the assistance of a coordinating directing group has emerged as an atom- and stepeconomical synthetic tools to transform C–H bonds into carbon-carbon or carbonheteroatom bonds. Although the strategies involving regioselective C–H cleavage assisted by various directing groups have been extensively reviewed in the literature, we now attempt to give an overview of the recent advances on phosphorus-containing functional group assisted C-H activation reactions catalyzed by transition-metal catalysts including mechanistic study and synthetic applications. The discussion is directed towards C-H olefination, C-H activation/cyclization, C-H arylation, C-H amination, C-H hydroxylation and acetoxylation as well as miscellaneous C-H activation.

scholarly journals Silicon Grignard Reagents as Nucleophiles in Transition-Metal-Catalyzed Allylic Substitution

Synthesis ◽  
2018 ◽  
Vol 51 (01) ◽  
pp. 233-239 ◽  
Author(s):  
Weichao Xue ◽  
Martin Oestreich
Keyword(s):  
Transition Metal ◽  
Metal Catalysts ◽  
Transition Metal Catalysts ◽  
Grignard Reagents ◽  
Allylic Substitution ◽  
Substitution Reactions ◽  
Cyclic System ◽  
Leaving Group ◽  
Transition Metal Catalyzed ◽  
Metal Catalyzed

A broad range of transition-metal catalysts is shown to promote allylic substitution reactions of allylic electrophiles with silicon Grignard reagents. The procedure was further elaborated for CuI as catalyst. The regioselectively is independent of the leaving group for primary allylic precursors, favoring α over γ. The stereochemical course of this allylic transposition was probed with a cyclic system, and anti-dia­stereoselectivity was obtained.

scholarly journals Modification of Biologically Active Plant Metabolites Via the Transition Metal Catalyzed Reactions

2013 ◽  
Vol 15 (3) ◽  
pp. 175 ◽  
Author(s):  
E.E. Shults
Keyword(s):  
Transition Metal ◽  
Heck Reaction ◽  
Cycloaddition Reaction ◽  
Biologically Active ◽  
Dipolar Cycloaddition ◽  
Plant Metabolites ◽  
Click Reactions ◽  
Transition Metal Catalyzed ◽  
Catalyzed Reactions ◽  
Metal Catalyzed

Developed by the author’s research laboratory methods of functionalization of some plant metabolites or their derivatives, viz., the eudesmane-type methylenelactones, diterpene and morphinane alkaloids, furanolabdanoids, and coumarins, using the transition metal catalyzed reactions, are reviewed. The activity<br />of linear methylene lactone of the eudesmane type in the Heck reaction are analyzed. It is shown that the outcome of the Heck reaction is significantly influenced by the structure of methylidenelactone. The Pd-catalyzed arylation of isoalantolactone with arylhalogenides or 6-bromodeoxyvasicinone occurred with<br />formation mainly of cross-coupling products with the (E) - configuration of the double bond. Synthesis of halogen derivatives of lappaconitine, tetrahydrothebaine and dihydrothebaine-hydroquinone and investigation of in the Heck or Sonogashira reactions gave the possibility for obtaining of new alkaloid derivatives with additional substituents in the aromatic rings. Homocoupling reaction or Sonogashira crosscoupling reaction of 5´- ethynyllappaconitine are used for synthesis of dimeric alkaloids of aconitane types. Pd-catalyzed amination of 2-(1,3-dibromoprop-2-ylidene)oreoselone and the transformations of oreoselone triflate, upon the action of palladium compounds allowed us to accomplish new modifications of linear furocoumarins. The method of enyne cycloisomerization of <em>ω</em>-alkynylfurans catalyzed with Au(III) was successfully obtained in the transformations of furanolabdanoids. The copper(I) salts catalyzed 1,3-dipolar cycloaddition reaction of azides to terminal alkynes belongs to the group of click-reactions was used in the synthesis of macrocyclic structures of labdane diterpenoids. The copper-catalyzed 1,3-dipolar cycloaddition reaction of 2 - azidooreoselone with various alkynes yielded diverse 2-(1,2,3-triazolyl)furocoumarins. The advantages of transition metal catalyzed reactions to the transformations of plant metabolites and its derivatives shown the possibility of introduction of several bioisosteric groups, and other fragments providing additional interactions and selectivity of binding with receptors and enzymes.

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