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.

Copper-Catalyzed Enantioselective Conjugate Addition to α,β-Unsaturated Aldehydes with Various Organometallic Reagents

Synthesis ◽  
2016 ◽  
Vol 48 (19) ◽  
pp. 3301-3308 ◽  
Author(s):  
Sylvie Goncalves-Contal ◽  
Ludovic Gremaud ◽  
Laëtitia Palais ◽  
Lucille Babel ◽  
Alexandre Alexakis
Keyword(s):  
Bond Formation ◽  
Conjugate Addition ◽  
Chiral Ligands ◽  
Grignard Reagents ◽  
Important Class ◽  
Reaction Conditions ◽  
Organometallic Reagents ◽  
Unsaturated Aldehydes

β-Substituted aldehydes constitute a very important class of compounds found in nature. Synthesis of this motif can be envisioned by C–C bond formation on enals. For this purpose, we report herein the development of enantioselective copper-catalyzed conjugate addition of various organometallic reagents to α,β-unsaturated aldehydes with (R)-H8BINAP, (R)-TolBINAP, and (R)-SEGPHOS as chiral ligands. Three sets of conditions were successfully developed and several enals were used. Reactivity and regio- and enantioselectivities were strongly dependent on reaction conditions and substrates. Good to excellent regio- and enantioselectivities were obtained with zinc reagents R2Zn and aluminum reagents R3Al. However, the asymmetric conjugate addition of Grignard reagents afforded only moderate to good regio- and enantioselectivities.

Pd Catalyzed N1/N4 Arylation of Piperazine for Synthesis of Drugs, Biological and Pharmaceutical Targets: An Overview of Buchwald Hartwig Amination Reaction of Piperazine in Drug Synthesis

2018 ◽  
Vol 15 (2) ◽  
pp. 208-220 ◽  
Author(s):  
Vaibhav Mishra ◽  
Tejpal Singh Chundawat
Keyword(s):  
Bond Formation ◽  
Catalyst Design ◽  
Biologically Active ◽  
Reaction Conditions ◽  
Biological Targets ◽  
Amination Reaction ◽  
Drug Synthesis ◽  
Substituted Piperazine ◽  
Approved Drugs ◽  
Fda Approved Drugs

Background: Substituted piperazine heterocycles are among the most significant structural components of pharmaceuticals. N1/N4 substituted piperazine containing drugs and biological targets are ranked 3rd in the top most frequent nitrogen heterocycles in U.S. FDA approved drugs. The high demand of N1/N4 substituted piperazine containing biologically active compounds and U.S. FDA approved drugs, has prompted the development of Pd catalyzed C-N bond formation reactions for their synthesis. Buchwald-Hartwig reaction is the key tool for the synthesis of these compounds. Objective: This review provides strategies for Pd catalyzed C-N bond formation at N1/N4 of piperazine in the synthesis of drugs and biological targets with diverse use of catalyst-ligand system and reaction parameters. Conclusion: It is clear from the review that a vast amount of work has been done in the synthesis of N1/N4 substituted piperazine containing targets under the Pd catalyzed Buchwald-Hartwig amination of aryl halides by using different catalyst-ligand systems. These methods have become increasingly versatile as a result of innovation in catalyst design and improvements in reaction conditions. This review gives an overview of recent utilization of Buchwald-Hartwig amination reaction in drug/target synthesis.

Modern Organic Synthesis in the Laboratory

2008 ◽  
Author(s):  
Jie Jack Li ◽  
Chris Limberakis ◽  
Derek A. Pflum
Keyword(s):  
Organic Chemistry ◽  
Graduate Students ◽  
Organic Synthesis ◽  
Functional Group ◽  
Bond Formation ◽  
Reaction Conditions ◽  
Carbon Bond ◽  
Oxidation Reduction ◽  
Carbon Carbon Bond ◽  
Daunting Task

Searching for reaction in organic synthesis has been made much easier in the current age of computer databases. However, the dilemma now is which procedure one selects among the ocean of choices. Especially for novices in the laboratory, it becomes a daunting task to decide what reaction conditions to experiment with first in order to have the best chance of success. This collection intends to serve as an "older and wiser lab-mate" one could have by compiling many of the most commonly used experimental procedures in organic synthesis. With chapters that cover such topics as functional group manipulations, oxidation, reduction, and carbon-carbon bond formation, Modern Organic Synthesis in the Laboratory will be useful for both graduate students and professors in organic chemistry and medicinal chemists in the pharmaceutical and agrochemical industries.

Preparation of aromatic amines by copper-catalyzed coupling of boronic acids with aqueous ammonia

2010 ◽  
Vol 88 (9) ◽  
pp. 964-968 ◽  
Author(s):  
Zhaoqiong Jiang ◽  
Zhiqing Wu ◽  
Lixia Wang ◽  
Di Wu ◽  
Xiangge Zhou
Keyword(s):  
Aromatic Amines ◽  
Aqueous Ammonia ◽  
Environmentally Friendly ◽  
Boronic Acids ◽  
Reaction Conditions ◽  
Highly Efficient ◽  
Primary Aromatic Amines

A simple, highly efficient, and environmentally friendly protocol for the synthesis of primary aromatic amines by catalytic coupling of aromatic boronic acids with aqueous ammonia has been developed by using commercial and inexpensive CuSO4·5H2O as catalyst without addition of other solvents under mild reaction conditions.

Crystallographic Structures of Human α-Thrombin Complexed to Peptide Boronic Acids Lacking a Positive Charge at P1. Evidence of Novel Interactions

1997 ◽  
Vol 119 (41) ◽  
pp. 9935-9936 ◽  
Author(s):  
Emmanuel Skordalakes ◽  
Richard Tyrell ◽  
Said Elgendy ◽  
Christopher A. Goodwin ◽  
Donovan Green ◽  
...  
Keyword(s):  
Positive Charge ◽  
Boronic Acids ◽  
Crystallographic Structures ◽  
Novel Interactions

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.

scholarly journals Rh-Catalyzed Conjugate Addition of Aryl and Alkenyl Boronic Acids to α-Methylene-β-lactones: Stereoselective Synthesis of trans-3,4-Disubstituted β-Lactones

2017 ◽  
Vol 19 (17) ◽  
pp. 4460-4463 ◽  
Author(s):  
Christian A. Malapit ◽  
Irungu K. Luvaga ◽  
Donald R. Caldwell ◽  
Nicholas K. Schipper ◽  
Amy R. Howell
Keyword(s):  
Stereoselective Synthesis ◽  
Conjugate Addition ◽  
Boronic Acids
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