Template Catalysis by Metal–Ligand Cooperation. C–C Bond Formation via Conjugate Addition of Non-activated Nitriles under Mild, Base-free Conditions Catalyzed by a Manganese Pincer Complex

2016 ◽  
Vol 138 (22) ◽  
pp. 6985-6997 ◽  
Author(s):  
Alexander Nerush ◽  
Matthias Vogt ◽  
Urs Gellrich ◽  
Gregory Leitus ◽  
Yehoshoa Ben-David ◽  
...  
Keyword(s):  
Bond Formation ◽  
Conjugate Addition ◽  
Pincer Complex ◽  
Metal Ligand

scholarly journals Rate Dependence on Inductive and Resonance Effects for the Organocatalyzed Enantioselective Conjugate Addition of Alkenyl and Alkynyl Boronic Acids to β-Indolyl Enones and β-Pyrrolyl Enones

Molecules ◽  
2021 ◽  
Vol 26 (6) ◽  
pp. 1615
Author(s):  
Amy Boylan ◽  
Thien S. Nguyen ◽  
Brian J. Lundy ◽  
Jian-Yuan Li ◽  
Ravikrishna Vallakati ◽  
...  
Keyword(s):  
Positive Charge ◽  
Bond Formation ◽  
Conjugate Addition ◽  
Reaction Rates ◽  
Boronic Acids ◽  
Key Factors ◽  
Resonance Contribution ◽  
Reaction Conditions ◽  
Resonance Effects ◽  
Resonance Stabilization

Two key factors bear on reaction rates for the conjugate addition of alkenyl boronic acids to heteroaryl-appended enones: the proximity of inductively electron-withdrawing heteroatoms to the site of bond formation and the resonance contribution of available heteroatom lone pairs to stabilize the developing positive charge at the enone β-position. For the former, the closer the heteroatom is to the enone β-carbon, the faster the reaction. For the latter, greater resonance stabilization of the benzylic cationic charge accelerates the reaction. Thus, reaction rates are increased by the closer proximity of inductive electron-withdrawing elements, but if resonance effects are involved, then increased rates are observed with electron-donating ability. Evidence for these trends in isomeric substrates is presented, and the application of these insights has allowed for reaction conditions that provide improved reactivity with previously problematic substrates.

scholarly journals Michael Addition of Imidazole to α, β -Unsaturated Carbonyl/Cyano Compound

2018 ◽  
Vol 5 (1) ◽  
pp. 18-31
Author(s):  
Seetaram Mohapatra ◽  
Nilofar Baral ◽  
Nilima Priyadarsini Mishra ◽  
Pravati Panda ◽  
Sabita Nayak
Keyword(s):  
Organic Chemistry ◽  
Amino Acids ◽  
Anticancer Agents ◽  
Michael Addition ◽  
Addition Reaction ◽  
Bond Formation ◽  
Conjugate Addition ◽  
Michael Addition Reaction ◽  
Cyano Compounds ◽  
Nitrogen Bond

Introduction: Aza-Michael addition is an important reaction for carbon-nitrogen bond formation in synthetic organic chemistry. Expalantion: Conjugate addition of imidazole to α,β-unsaturated carbonyl/cyano compounds provides significant numbers of the biologically and synthetically interesting products, such as β-amino acids and β-lactams, which have attracted great attention for their use as key intermediates of anticancer agents, antibiotics and other drugs. Conclusion: This review addresses most significant method for the synthesis of N-substituted imidazole derivatives following Michael addition reaction of imidazole to α,β-unsaturated carbonyl/cyano compounds using ionic liquid/base/acid/enzyme as catalysts from year 2007-2017.

Thermodynamics of metal-ligand bond formation. XII. Adducts of Monothio-β-diketone complexes with pyridine and bipyridine

1974 ◽  
Vol 27 (6) ◽  
pp. 1351 ◽  
Author(s):  
DR Dakternieks ◽  
DP Graddon
Keyword(s):  
Thermodynamic Data ◽  
Benzene Solution ◽  
Bond Formation ◽  
Enthalpies Of Formation ◽  
Calorimetric Titration ◽  
Metal Ligand ◽  
Ligand Bond

Thermodynamic data are reported for the addition of pyridine and bipyridine in benzene solution to monothio-β-diketone complexes, ML2, of nickel(11), copper(11), zinc(11) and mercury(11). NiL2 gives NiL2(py)2 and NiL(bpy); ZnL2 gives ZnL2(py) and ZnL2(bpy); in both cases the data show that bipyridine is bidentate. CuL2 gives CuL2 (py) and CuL2 (bpy), with almost equal enthalpies of formation, but the higher stability of CuL2(bpy) shows bipyridine is probably bidentate. HgL2 gives HgL2(py) and a reaction with bipyridine which shows that an extremely unstable adduct is formed. All data were obtained by calorimetric titration.

Thermodynamics of metal-ligand bond formation

1977 ◽  
Vol 132 (1) ◽  
pp. 1-7 ◽  
Author(s):  
D.P. Graddon ◽  
J. Mondal
Keyword(s):  
Bond Formation ◽  
Metal Ligand ◽  
Ligand Bond

Rh(I) Complex with a Tridentate Pyridine–Amino–Olefin Actor Ligand–Metal–Ligand Cooperative Activation of CO2 and Phenylisocyanate under C–C and Rh–E (E = O, N) Bond Formation

2019 ◽  
Vol 38 (8) ◽  
pp. 1787-1799 ◽  
Author(s):  
Isabell Heuermann ◽  
Benjamin Heitmann ◽  
Rasmus Stichauer ◽  
Daniel Duvinage ◽  
Matthias Vogt
Keyword(s):  
Bond Formation ◽  
Cooperative Activation ◽  
Metal Ligand

Thermodynamics of metalligand bond formation

1986 ◽  
Vol 317 (2) ◽  
pp. 153-157 ◽  
Author(s):  
Y. Farhangi ◽  
D.P. Graddon
Keyword(s):  
Bond Formation ◽  
Metal Ligand ◽  
Ligand Bond

scholarly journals Heterolytic Cleavage of Dihydrogen by an Iron(II) PNP Pincer Complex via Metal–Ligand Cooperation

2013 ◽  
Vol 32 (15) ◽  
pp. 4114-4121 ◽  
Author(s):  
Bernhard Bichler ◽  
Christian Holzhacker ◽  
Berthold Stöger ◽  
Michael Puchberger ◽  
Luis F. Veiros ◽  
...  
Keyword(s):  
Heterolytic Cleavage ◽  
Pincer Complex ◽  
Metal Ligand

Thermodynamics of metal-ligand bond formation. II. Zinc, cadmium, and mercury(II) complexes of o,o-dialkyldithiophosphates

1971 ◽  
Vol 24 (10) ◽  
pp. 2077 ◽  
Author(s):  
DR Dakternieks ◽  
DP Graddon
Keyword(s):  
Metal Atom ◽  
Alkyl Group ◽  
Thermodynamic Data ◽  
Benzene Solution ◽  
Bond Formation ◽  
Free Energies ◽  
Zinc Cadmium ◽  
Metal Ligand ◽  
Ligand Bond

The reactions of 0,O-dialkyldithiophosphato complexes, {(R0)2PSz}zM (M = Zn, Cd, Hg), to form dimers and 1 : 1 and 1 : 2 adducts with pyridine have been studied calorimetrically in benzene solution a t 30�C. While variation of the alkyl group has little effect, variation of the metal atom causes marked changes in both free energies and enthalpies of reaction. Average values of thermodynamic data obtained are as follows (AGOao3 and AH0300 in k J mol-l, AS0a03 in J K-l mol-l) :

Thermodynamics of metal-ligand bond formation. XXV. Addition of bases to Bis[O,O'-diethyl thiomalonato]nickel(II) in various solvents

1977 ◽  
Vol 30 (3) ◽  
pp. 495 ◽  
Author(s):  
L Ang ◽  
DP Graddon ◽  
VAK Ng
Keyword(s):  
Thermodynamic Data ◽  
Driving Force ◽  
Bond Formation ◽  
Adduct Formation ◽  
Calorimetric Measurements ◽  
Carbon Tetra ◽  
Metal Ligand ◽  
Ligand Bond

Thermodynamic data have been obtained from spectroscopic and calorimetric measurements for the addition of pyridine and 4- methylpyridine to bis(O,O?-diethyl thiomalonato)nickel(II), Ni(etm)2, in solution in cyclohexane, benzene, 1,2-dichloroethane, acetonitrile, butan-2-one and carbon tetra-chloride. In each solvent two base molecules add successively, giving Ni(etm)2B then Ni(etm)2B2. There are only small variations in K1 and K2 in different solvents; typically K1 ≈ 200, K2 ≈ 100 l. mol-1, ΔH�1+2 ≈ -65, ΔH�2 ≈ 0 kJ mol-1 at 30�C, but in benzene and cyclohexane ΔH�2 ≈ -25 and in cyclohexane ΔH�1+2 ≈ -100 kJ mol-1. The main driving force for adduct formation is apparently the formation of the first Ni-N bond, which is accompanied by a spin change.

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