Synthesis,Biological Studies of Macrocyclic Transition Metal Complexes
Synthesis,Biological Studies of Macrocyclic Transition Metal Complexes

Author: Rayees Sheikh

Publisher: LAP Lambert Academic Publishing

Published: 2012-07

Total Pages: 156

ISBN-13: 9783659146572

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This book presents the important facts about the synthesis and biological studies of macrocyclic transition metal complexes. A detailed synthetic discussion of the reaction steps in each mechanism and their relationship with transition metal complexes has been considered. Macrocyclic ligands and their transition metal complexes depends upon the nature of reactants and the corresponding metal ion. The macrocyclic ligand are a growing class of compounds with varying chemistry a wide range of different molecular topologies and set of donor atoms. Aza type ligands appear as very promising to be used as antifertile, antibacterial, antifungal and other biological properties. Macrocyclic metal complexes play a central role in the construction of molecular materials, which display magnetic properties and find applications in material and supramolecular chemistry and biochemistry. It is believed that the present book will provide a succinct and clear introduction to synthesis, characterization and biological studies macrocyclic ligands with transition metal complexes that meets the needs of researchers at a variety of levels in several disciplines.

Transition Metal-Mediated Synthesis and Functionalization of Macrocycles
Transition Metal-Mediated Synthesis and Functionalization of Macrocycles

Author: Sedef Karabiyikoglu

Publisher:

Published: 2015

Total Pages: 391

ISBN-13:

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Transition metal-mediated synthesis and functionalization of macrocycles were investigated. A novel synthetic strategy was discovered to build macrocyclic enynes; vic-dibromo tetrasubstituted alkenes were utilized as highly effective protected alkyne groups in selective ene-ene ring closing metathesis reactions of (E)-dibromotrienes. Macrocyclic enynes with varied sizes and functionality were synthesized in excellent yields by facile Zn-promoted deprotection of (E)-dibromodiene rings. The new strategy circumvented high catalyst loadings and reaction condition restrictions; thus, was proven superior to traditional alkyne protection methods employing dicobalt octacarbonyl complexations. Cyclic enynes were obtained in a more step-economic and efficient manner compared to classical SN2 ring closing processes. The reactivity and utility of enyne rings were showcased by platinum(II)-catalyzed transannular cyclopropanations. The first dicobalt hexacarbonyl-promoted transannular [4+2] cycloaddition reactions were demonstrated. Optimized cycloadditions for macrocyclic dicobalt-dienyne complexes afforded target tricyclic scaffolds in a more effective manner than thermal transannular Diels-Alder reactions of metal-free dienyne rings. Further, dicobalt hexacarbonyl complexes of unactivated dienophiles underwent intermolecular room temperature-[4+2] cycloadditions with unactivated dienes leading to products that are inaccessible by thermal Diels-Alder reactions. Cycloaddition reactions of complexes were highly selective; [4+2] reaction adducts were obtained stereospecifically and competing Pauson-Khand reactions were not detected. Functionalizations of enyne macrocycles through intermolecular and transannular reactions of their corresponding dicobalt complexes were studied. Novel complex polycycles were prepared by intramolecular and intermolecular [2+2+2], [2+2+1+1], [2+2+1] cycloadditions. The chemoselectivity of dicobalt-promoted cycloadditions was altered by varying the promoter and solvents utilized. The first transannular Pauson-Khand reaction was discovered. The novel synthetic method was optimized and structural requirements for reaction substrates were investigated.