ChemInform Abstract: Modification of Biologically Active Plant Metabolites via the Transition Metal Catalyzed Reactions

ChemInform ◽  
2014 ◽  
Vol 45 (50) ◽  
pp. no-no
Author(s):  
E. E. Shults
Keyword(s):  
Transition Metal ◽  
Biologically Active ◽  
Plant Metabolites ◽  
Transition Metal Catalyzed ◽  
Catalyzed Reactions ◽  
Metal Catalyzed

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.

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.

Monodentate Trialkylphosphines: Privileged Ligands in Metal-catalyzed Crosscoupling Reactions

2020 ◽  
Vol 24 (3) ◽  
pp. 231-264 ◽  
Author(s):  
Kevin H. Shaughnessy
Keyword(s):  
Transition Metal ◽  
Cross Coupling ◽  
Coupling Reactions ◽  
Cross Coupling Reactions ◽  
Aryl Bromides ◽  
Wide Range ◽  
Sterically Demanding ◽  
Transition Metal Catalyzed ◽  
Catalyzed Reactions ◽  
Metal Catalyzed

Phosphines are widely used ligands in transition metal-catalyzed reactions. Arylphosphines, such as triphenylphosphine, were among the first phosphines to show broad utility in catalysis. Beginning in the late 1990s, sterically demanding and electronrich trialkylphosphines began to receive attention as supporting ligands. These ligands were found to be particularly effective at promoting oxidative addition in cross-coupling of aryl halides. With electron-rich, sterically demanding ligands, such as tri-tertbutylphosphine, coupling of aryl bromides could be achieved at room temperature. More importantly, the less reactive, but more broadly available, aryl chlorides became accessible substrates. Tri-tert-butylphosphine has become a privileged ligand that has found application in a wide range of late transition-metal catalyzed coupling reactions. This success has led to the use of numerous monodentate trialkylphosphines in cross-coupling reactions. This review will discuss the general properties and features of monodentate trialkylphosphines and their application in cross-coupling reactions of C–X and C–H bonds.

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 Transition metal-catalyzed reactions of N-sulfinyl imines

2021 ◽  
pp. 153104
Author(s):  
Francisco Foubelo ◽  
Carmen Nájera ◽  
José M. Sansano ◽  
Miguel Yus
Keyword(s):  
Transition Metal ◽  
Transition Metal Catalyzed ◽  
Catalyzed Reactions ◽  
Metal Catalyzed

Iodide effects in transition metal catalyzed reactions

2004 ◽  
pp. 3409 ◽  
Author(s):  
Peter M. Maitlis ◽  
Anthony Haynes ◽  
Brian R. James ◽  
Marta Catellani ◽  
Gian Paolo Chiusoli
Keyword(s):  
Transition Metal ◽  
Transition Metal Catalyzed ◽  
Catalyzed Reactions ◽  
Metal Catalyzed
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