Helicity control in the synthesis of helicenes and related compounds

2006 ◽  
Vol 78 (2) ◽  
pp. 495-499 ◽  
Author(s):  
Ivo Starý ◽  
Irena G. Stará ◽  
Zuzana Alexandrová ◽  
Petr Sehnal ◽  
Filip Teplý ◽  
...  
Keyword(s):  
Asymmetric Synthesis ◽  
Kinetic Control ◽  
Thermodynamic Control ◽  
Further Development ◽  
Related Compounds

Asymmetric synthesis of helicenes and their congeners has been demonstrated to rely either on enantioselective Ni0/PR3*-catalyzed [2+2+2] cycloisomerization of triynes or on diastereoselective CoI-catalyzed [2+2+2] cycloisomerization of chiral triynes. The former approach providing tetrahydrohelicenes in a nonracemic form requires further development as moderate enantioselectivities (up to 54 % ee) have so far been achieved under kinetic control. The latter approach affording helicene-like structures in a diastereomerically enriched form allows for reaching good to excellent diastereoselectivities (up to 100:0) under thermodynamic control.

Diastereoselective Addition of α-Metalated Sulfoxides to Imines Revisited: Mechanism, Computational Studies, and the Effect of External Chiral Ligands

2003 ◽  
Vol 68 (5) ◽  
pp. 885-898 ◽  
Author(s):  
Brian Pedersen ◽  
Tobias Rein ◽  
Inger Søtofte ◽  
Per-Ola Norrby ◽  
David Tanner
Keyword(s):  
Reaction Time ◽  
Low Temperature ◽  
Asymmetric Synthesis ◽  
Chiral Ligands ◽  
Quantum Mechanical ◽  
Kinetic Control ◽  
Computational Studies ◽  
Quantum Mechanical Calculations ◽  
Short Reaction Time ◽  
Diastereoselective Addition

Some new results on asymmetric synthesis via the addition of α-metalated methyl tolyl sulfoxides to imines are presented. Good diastereoselectivity (up to >98% d.e. for product 3g) can be obtained under conditions of kinetic control (short reaction time, low temperature). The transition state (a six-membered "flat chair") was probed by quantum mechanical calculations, which underpinned the idea of using external chiral ligands to enhance the diastereoselectivity of otherwise moderately selective reactions. In this way, the diastereomeric ratio of the product 3a could be raised from (84:16) to (>99:1) by use of a readily available C2-symmetric bis(sulfonamide) ligand.

scholarly journals AKR1C3 Inhibitory Potency of Naturally-occurring Amaryllidaceae Alkaloids of Different Structural Types

2017 ◽  
Vol 12 (2) ◽  
pp. 1934578X1701200 ◽  
Author(s):  
Daniela Hulcová ◽  
Kateřina Breiterová ◽  
Lucie Zemanová ◽  
Tomáš Siatka ◽  
Marcela Šafratová ◽  
...  
Keyword(s):  
Isoquinoline Alkaloid ◽  
Inhibitory Potency ◽  
Amaryllidaceae Alkaloids ◽  
Naturally Occurring ◽  
Pathological Conditions ◽  
Model Substance ◽  
Inhibition Potency ◽  
Further Development ◽  
Related Compounds ◽  
Proliferative Signaling

Aldo-keto reductase 1C3 (AKR1C3) is an important human enzyme that participates in the reduction of steroids and prostaglandins, which leads to proliferative signaling. AKR1C3 is frequently upregulated in various cancers, and this enzyme has been suggested as a therapeutic target for the treatment of these pathological conditions. The fact that the isoquinoline alkaloid stylopine has been identified as a potent AKR1C3 inhibitor has prompted us to screen a library of diverse types of Amaryllidaceae alkaloids, which biogenetically are isoquinoline alkaloids, on a recombinant form of AKR1C3. From the tested compounds, only tazettine showed moderate AKR1C3 inhibitory potency with an IC50 value of 15.8 ± 1.2 μM. Tazettine is a common Amaryllidaceae alkaloid, which could be used as a model substance for the further development of either analogues or related compounds with better inhibition potency.

Experimental and Theoretical Investigation of the Reaction of Secondary Amines with Maleic Anhydride

2017 ◽  
Vol 70 (12) ◽  
pp. 1247 ◽  
Author(s):  
Manjinder Kour ◽  
Raakhi Gupta ◽  
Raj K. Bansal
Keyword(s):  
Maleic Anhydride ◽  
Carbonyl Group ◽  
Carbonyl Compounds ◽  
Secondary Amines ◽  
Kinetic Control ◽  
Thermodynamic Control ◽  
Carbonyl Carbon ◽  
Fukui Functions ◽  
Unsaturated Carbonyl Compound ◽  
Condensed Fukui Functions

The reaction of secondary amines, namely 1-methylpiperazine, pyrrolidine, morpholine, 2-methylpiperidine, and diethylamine, with maleic anhydride has been investigated experimentally and theoretically at the DFT level. Under kinetic control, i.e. at −78°C or −15°C, amines add across the C=O functionality exclusively and the initially formed addition products isomerize to the corresponding N-substituted maleimic acid derivatives. In contrast to the acyclic α,β-unsaturated carbonyl compounds, amine does not add across the C=C functionality in maleic anhydride even under thermodynamic control. This behaviour of maleic anhydride can be rationalized on the basis of the local condensed Fukui functions, which reveal that the carbonyl carbon atoms in maleic anhydride are much harder than in an acyclic α,β-unsaturated carbonyl compound, such as acrolein. This prompts the amines to attack the carbonyl group in maleic anhydride exclusively.

scholarly journals QUANTUM CHEMITRY STUDY ON STRUCTURES, ACTIVITIES AND REACTIONS OF ONIUM-BORONIUM DICATIONS

2010 ◽  
Vol 13 (2) ◽  
pp. 45-52
Author(s):  
Thanh Tho Bui ◽  
Tran Thi Bao Vo
Keyword(s):  
Activation Energy ◽  
Intrinsic Reaction Coordinate ◽  
Kinetic Control ◽  
Ab Initio Methods ◽  
Thermodynamic Control ◽  
Imaginary Frequency ◽  
Theoretical Investigations ◽  
Transition Structures ◽  
Frequency Calculation ◽  
Energy Activation

This paper provides information about theoretical investigations of structures of onium-boronium dications X+BH3+, X+BH5+; (X= NH3, PH3, H2O, H2S) and some reactions of them in thermodynamic control and kinetic control. Two kinds of reactions studied are complexation of onium-boronium dications X+BH3+ with H2 leading to X+BH5+ and deprotonation of X+BH5+ to give X+BH4. The similar studies with boronium ion analog BH4+ and BH6+ is carried out and results obtained pointed out that the eletrophility of onium-boronium dications is more stronger than that of boronium ion: onium-boronium dications X+BH3+, X+BH5+ are superelectrophiles. The structures of onium-boronium dications and boronium ions are optimized by using ab initio methods at the MP2/6-311+G** level of Gaussian 03W, revision B.04 and represented with Gaussview 3.0. Frequency calculation is performed to assure the obtained structures corresponding to minimun energies and have no any imaginary frequency. The transition structures are calculated and verified due to Intrinsic Reaction Coordinate Calculations. The properties of structures, as MP2 energy, Gibbs free energy, activation energy are also examined.

Asymmetric Synthesis of C1-Chiral THIQs with Imines in Isoquinoline Rings

Synthesis ◽  
2020 ◽  
Vol 52 (22) ◽  
pp. 3337-3355
Author(s):  
Dan Li ◽  
Wei Gao ◽  
Xiaochao Chen
Keyword(s):  
Asymmetric Synthesis ◽  
Biological Activities ◽  
Asymmetric Reactions ◽  
Structural Units ◽  
Mannich Reactions ◽  
Asymmetric Reaction ◽  
Azomethine Imines ◽  
Catalytic Asymmetric ◽  
Further Development ◽  
New Strategies

Tetrahydroisoquinoline (THIQ) scaffolds are important structural units that widely exist in a variety of natural alkaloids and synthetic analogues. Asymmetric synthesis of C1-chiral THIQ is of particular importance due to its significant pharmaceutical, agrochemical, and other biological activities, and the usually distinct bioactivities exhibited by the two enantiomers. In this review, we highlight the significant advances achieved in this field, present recent asymmetric synthesis with imines in isoquinoline rings ordered according to the sequence of various substrate types. New strategies could be inspired and more types of substrates need further development.1 Introduction2 Catalytic Asymmetric Reaction of Dihydroisoquinolines2.1 Asymmetric Reactions of 3,4-Dihydroisoquinolines2.2 Asymmetric Reactions of Dihydroisoquinolinium Salts2.3 Asymmetric Reactions of C,N-Cyclic N′-Acyl Azomethine Imines2.3.1 NED [3+2] Cycloaddition of C,N-Cyclic N′-Acyl Azomethine Imines2.3.2 IED [3+2] Cycloaddition of C,N-Cyclic N′-Acyl Azomethine Imines2.3.3 [3+3] Cycloaddition of C,N-Cyclic N′-Acyl Azomethine Imines2.3.4 [4+3] Cycloaddition of C,N-Cyclic N′-Acyl Azomethine Imines2.3.5 Asymmetric Addition Reactions to C,N-Cyclic N′-Acyl Azomethine Imines2.4 Asymmetric Reactions of C,N-Cyclic Nitrones3 Catalytic Asymmetric Mannich Reactions of Isoquinolines4 Conclusions and Perspectives

scholarly journals Metal control of selectivity in acetate-assisted C–H bond activation: an experimental and computational study of heterocyclic, vinylic and phenylic C(sp2)–H bonds at Ir and Rh

2014 ◽  
Vol 5 (6) ◽  
pp. 2340-2346 ◽  
Author(s):  
Kevin J. T. Carr ◽  
David L. Davies ◽  
Stuart A. Macgregor ◽  
Kuldip Singh ◽  
Barbara Villa-Marcos
Keyword(s):  
Bond Activation ◽  
Computational Study ◽  
Metal Catalyst ◽  
Kinetic Control ◽  
Dft Studies ◽  
Thermodynamic Control

Experimental and DFT studies show the selectivity of C–H bond activation at [MCl2Cp*]2 (M = Ir, Rh) species can be controlled by the choice of metal catalyst, reflecting kinetic control at M = Ir and thermodynamic control at M = Rh.

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