Determination of the Origin of Stereoselectivity in Multiple-Transition-State Reactions Using DFT Calculations:  Enantioselective Synthesis of Homoallylic Alcohols from Aliphatic Methyl Ketones via an Auxiliary-Mediated Allylation

2008 ◽  
Vol 130 (13) ◽  
pp. 4386-4395 ◽  
Author(s):  
Lutz F. Tietze ◽  
Tom Kinzel ◽  
Stefan Schmatz
Keyword(s):  
Dft Calculations ◽  
Transition State ◽  
Enantioselective Synthesis ◽  
Methyl Ketones ◽  
Homoallylic Alcohols

scholarly journals Highly Enantioselective Synthesis of Indazoles with a C3-Quaternary Chiral Center Using CuH Catalysis

2019 ◽  
Author(s):  
Yuxuan Ye ◽  
Ilia Kevlishvili ◽  
Sheng Feng ◽  
Peng Liu ◽  
Stephen L. Buchwald
Keyword(s):  
Density Functional Theory ◽  
Dft Calculations ◽  
Transition State ◽  
Density Functional ◽  
Enantioselective Synthesis ◽  
Chiral Center ◽  
Functional Theory ◽  
Type Transition ◽  
Allyl Complex ◽  
Quaternary Stereocenters

<div><div><div><p>C3-substituted 1H-indazoles are useful and important substructures in many pharmaceuticals. Methods for direct C3- functionalization of indazoles are relatively rare, compared to reactions developed for the more nucleophilic N1 and N2 positions. Herein, we report a highly C3-selective allylation reaction of 1H-N-(benzoyloxy)indazoles using CuH catalysis. A variety of C3-allyl 1H-indazoles with quaternary stereocenters were efficiently prepared with high levels of enantioselectivity. Density functional theory (DFT) calculations suggest that the indazole addition to copper allyl complex proceeds through an enantioselectivity-determining six- membered Zimmerman-Traxler-type transition state. The enantioselectivity is governed both by the ligand-substrate steric interac- tions and the steric repulsions with the pseudoaxial substituent in the six-membered allylation transition state.</p></div></div></div>

scholarly journals Highly Enantioselective Synthesis of Indazoles with a C3-Quaternary Chiral Center Using CuH Catalysis

2019 ◽  
Author(s):  
Yuxuan Ye ◽  
Ilia Kevlishvili ◽  
Sheng Feng ◽  
Peng Liu ◽  
Stephen L. Buchwald
Keyword(s):  
Density Functional Theory ◽  
Dft Calculations ◽  
Transition State ◽  
Density Functional ◽  
Enantioselective Synthesis ◽  
Chiral Center ◽  
Functional Theory ◽  
Type Transition ◽  
Allyl Complex ◽  
Quaternary Stereocenters

<div><div><div><p>C3-substituted 1H-indazoles are useful and important substructures in many pharmaceuticals. Methods for direct C3- functionalization of indazoles are relatively rare, compared to reactions developed for the more nucleophilic N1 and N2 positions. Herein, we report a highly C3-selective allylation reaction of 1H-N-(benzoyloxy)indazoles using CuH catalysis. A variety of C3-allyl 1H-indazoles with quaternary stereocenters were efficiently prepared with high levels of enantioselectivity. Density functional theory (DFT) calculations suggest that the indazole addition to copper allyl complex proceeds through an enantioselectivity-determining six- membered Zimmerman-Traxler-type transition state. The enantioselectivity is governed both by the ligand-substrate steric interac- tions and the steric repulsions with the pseudoaxial substituent in the six-membered allylation transition state.</p></div></div></div>

Reactions of an Aluminium(I) Reagent with 1,2-, 1,3- and 1,5-Dienes: Dearomatisation, Reversibility, and a Pericyclic Mechanism

2019 ◽  
Author(s):  
Clare Bakewell ◽  
Martí Garçon ◽  
Richard Y Kong ◽  
Louisa O'Hare ◽  
Andrew J. P. White ◽  
...  
Keyword(s):  
Reaction Mechanism ◽  
Dft Calculations ◽  
Transition State ◽  
Reaction Pathways ◽  
Aromatic Rings ◽  
Aromatic Character ◽  
Pericyclic Reaction

The reactions of an aluminium(I) reagent with a series of 1,2-, 1,3- and 1,5-dienes are reported. In the case of 1,3-dienes the reaction occurs by a pericyclic reaction mechanism, specifically a cheletropic cycloaddition, to form aluminocyclopentene containing products. This mechanism has been interrogated by stereochemical experiments and DFT calculations. The stereochemical experiments show that the (4+1) cycloaddition follows a suprafacial topology, while calculations support a concerted albeit asynchronous pathway in which the transition state demonstrates aromatic character. Remarkably, the substrate scope of the (4+1) cycloaddition includes dienes that are either in part, or entirely, contained within aromatic rings. In these cases, reactions occur with dearomatisation of the substrate and can be reversible. In the case of 1,2- or 1,5-dienes complementary reactivity is observed; the orthogonal nature of the C=C π-bonds (1,2-diene) and the homoconjugated system (1,5-diene) both disfavour a (4+1) cycloaddition. Rather, reaction pathways are determined by an initial (2+1) cycloaddition to form an aluminocyclopropane intermediate which can in turn undergo insertion of a further C=C π-bond leading to complex organometallic products that incorporate fused hydrocarbon rings.

scholarly journals Rapid Organocatalytic Chirality Analysis of Amines, Amino Acids, Alcohols, Amino Alcohols and Diols with Achiral Iso(thio)cyanate Probes

2021 ◽  
Author(s):  
Eryn Nelson ◽  
Jeffrey S. S. K. Formen ◽  
Christian Wolf
Keyword(s):  
Amino Acids ◽  
Absolute Configuration ◽  
Rapid Determination ◽  
Amino Alcohols ◽  
Enantioselective Synthesis ◽  
Widespread Occurrence ◽  
Chiral Compounds ◽  
New Methods ◽  
The Absolute

The widespread occurrence and significance of chiral compounds does not only require new methods for their enantioselective synthesis but also efficient tools that allow rapid determination of the absolute configuration,...

scholarly journals Determination of the hyperfine magnetic field in magnetic carbon-based materials: DFT calculations and NMR experiments

2015 ◽  
Vol 5 (1) ◽  
Author(s):  
Jair C. C. Freitas ◽  
Wanderlã L. Scopel ◽  
Wendel S. Paz ◽  
Leandro V. Bernardes ◽  
Francisco E. Cunha-Filho ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Dft Calculations ◽  
Hyperfine Magnetic Field ◽  
Magnetic Carbon ◽  
Carbon Based

Determination of reactive properties of 1-butyl-3-methylimidazolium taurate ionic liquid employing DFT calculations

2016 ◽  
Vol 222 ◽  
pp. 796-803 ◽  
Author(s):  
Stevan Armaković ◽  
Sanja J. Armaković ◽  
Milan Vraneš ◽  
Aleksandar Tot ◽  
Slobodan Gadžurić
Keyword(s):  
Ionic Liquid ◽  
Dft Calculations ◽  
Reactive Properties

scholarly journals Asymmetric Addition of Allylsilanes to Aldehydes – A Cr/Photoredox Dual Catalytic Approach Complementing the Hosomi–Sakurai Reaction

2021 ◽  
Author(s):  
Felix Schäfers ◽  
Subhabrata Dutta ◽  
Roman Kleinmans ◽  
Christian Mück-Lichtenfeld ◽  
Frank Glorius
Keyword(s):  
Organic Chemistry ◽  
Transition State ◽  
Bioactive Compound ◽  
General Strategy ◽  
Acid Activation ◽  
Mechanistic Studies ◽  
Mild Conditions ◽  
Homoallylic Alcohols ◽  
Synthetic Utility ◽  
Fundamental Transformation

The allylation of aldehydes is a fundamental transformation in synthetic organic chemistry. Among the multitude of available reagents, especially allylsilanes have been established as preferred allyl source. As initially reported by Hosomi & Sakurai, these non-toxic and highly stable reagents add to carbonyls via an open transition state upon Lewis acid activation. Herein, we report a general strategy to access a variety of valuable homoallylic alcohols in opposite chemo- and diastereoselectivity to the established Hosomi–Sakurai conditions by switching to photocatalytic activation in combination with a closed transition state (Chromium catalysis). Moreover, this dual catalytic approach displays a straightforward way to introduce excellent levels of enantioselectivity and its mild conditions allow for a broad substrate scope including chiral boron-substituted products as a highlight. To emphasize the synthetic utility, our method was applied as the key step in the synthesis of a bioactive compound and in the late-stage functionalization of steroid derivatives. Detailed mechanistic studies and DFT calculations hint towards an unprecedented photo-initiated chain being operative.

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