scholarly journals Stereoselective Synthesis and Investigation of Isopulegol-Based Chiral Ligands

2019 ◽  
Vol 20 (16) ◽  
pp. 4050 ◽  
Author(s):  
Tam Minh Le ◽  
Tamás Szilasi ◽  
Bettina Volford ◽  
András Szekeres ◽  
Ferenc Fülöp ◽  
...  
Keyword(s):  
Antimicrobial Activity ◽  
Ring Opening ◽  
Stereoselective Synthesis ◽  
Substituent Effects ◽  
Ring Closure ◽  
Chiral Ligands ◽  
Primary Amines ◽  
Structure Activity ◽  
Stereoselective Reactions ◽  
Stereoselective Epoxidation

A library of isopulegol-based bi-, tri- and tetrafunctional chiral ligands has been developed from commercially available (−)-isopulegol and applied as chiral catalysts in the addition of diethylzinc to benzaldehyde. Michael addition of primary amines towards α-methylene-γ-butyrolactone, followed by reduction, was accomplished to provide aminodiols in highly stereoselective transformations. Stereoselective epoxidation of (+)-neoisopulegol, derived from natural (−)-isopulegol, and subsequent oxirane ring opening with primary amines afforded aminodiols. The regioselective ring closure of N-substituted aminodiols with formaldehyde was also investigated. Hydroxylation of (+)-neoisopulegol resulted in diol, which was then transformed into aminotriols by aminolysis of its epoxides. Dihydroxylation of (+)-neoisopulegol or derivatives with OsO4/NMO gave neoisopulegol-based di-, tri- and tetraols in highly stereoselective reactions. The antimicrobial activity of aminodiol and aminotriol derivatives as well as di-, tri- and tetraols was also explored. In addition, structure–activity relationships were examined by assessing substituent effects on the aminodiol and aminotriol systems.

scholarly journals Stereoselective Synthesis and Antiproliferative Activity of Steviol-Based Diterpen Aminodiols

2019 ◽  
Vol 21 (1) ◽  
pp. 184
Author(s):  
Dániel Ozsvár ◽  
Viktória Nagy ◽  
István Zupkó ◽  
Zsolt Szakonyi
Keyword(s):  
Antiproliferative Activity ◽  
Ring Opening ◽  
Stereoselective Synthesis ◽  
Click Reaction ◽  
Substituent Effects ◽  
Ring Closure ◽  
Secondary Amines ◽  
Structure Activity ◽  
Cis And Trans ◽  
Benzyl Substituent

A library of steviol-based trifunctional chiral ligands was developed from commercially available natural stevisoide and applied as chiral catalysts in the addition of diethylzinc to benzaldehyde. The key intermediate steviol methyl ester was prepared according to literature procedure. Depending on the epoxidation process, both cis- and trans-epoxyalcohols were obtained. Subsequent oxirane ring opening with primary and secondary amines afforded 3-amino-1,2-diols. The ring opening with sodium azide followed by a “click” reaction with alkynes resulted in dihydroxytriazoles. The regioselective ring closure of N-substituted aminodiols with formaldehyde was also investigated. The resulting steviol-type aminodiols were tested against a panel of human adherent cancer cell lines (A2780, SiHa, HeLa, and MDA-MB-231). It was consistently found that the N-benzyl substituent is an essential part within the molecule and the ring closure towards N-benzyl substituted oxazolidine ring system increased the antiproliferative activity to a level comparable with that of cisplatine. In addition, structure–activity relationships were examined by assessing substituent effects on the aminodiol systems.

scholarly journals Synthesis and Application of 1,2-Aminoalcohols with Neoisopulegol-Based Octahydrobenzofuran Core

Molecules ◽  
2019 ◽  
Vol 25 (1) ◽  
pp. 21 ◽  
Author(s):  
Fatima Zahra Bamou ◽  
Tam Minh Le ◽  
Bettina Volford ◽  
András Szekeres ◽  
Zsolt Szakonyi
Keyword(s):  
Antimicrobial Activity ◽  
Secondary Amine ◽  
Ring Opening ◽  
Ring Closure ◽  
Oxirane Ring ◽  
Primary Amines ◽  
Chiral Catalysts ◽  
Ring Systems ◽  
Stereoselective Reaction ◽  
Stereoselective Epoxidation

A library of 1,2-aminoalcohol derivatives with a neoisopulegol-based octahydrobenzofuran core was developed and applied as chiral catalysts in the addition of diethylzinc to benzaldehyde. The allylic chlorination of (+)-neoisopulegol, derived from natural (–)-isopulegol followed by cyclization, gave the key methyleneoctahydrobenzofuran intermediate. The stereoselective epoxidation of the key intermediate and subsequent oxirane ring opening with primary amines afforded the required 1,2-aminoalcohols. The ring closure of the secondary amine analogues with formaldehyde provided spiro-oxazolidine ring systems. The dihydroxylation of the methylenetetrahydrofuran moiety with OsO4/NMO (4-methylmorpholine N-oxide) resulted in the formation of a neoisopulegol-based diol in a highly stereoselective reaction. The antimicrobial activity of both the aminoalcohol derivatives and the diol was also explored.

scholarly journals Synthesis and Transformation of (-)-Isopulegol-Based Chiral β-Aminolactones and β-Aminoamides

2018 ◽  
Vol 19 (11) ◽  
pp. 3522 ◽  
Author(s):  
Tam Le ◽  
Péter Bérdi ◽  
István Zupkó ◽  
Ferenc Fülöp ◽  
Zsolt Szakonyi
Keyword(s):  
Ring Opening ◽  
Lactone Ring ◽  
Substituent Effects ◽  
Ring System ◽  
Secondary Amines ◽  
Amino Acid Derivatives ◽  
Structure Activity ◽  
Primary And Secondary Amines ◽  
Stereoselective Reactions ◽  
Antiproliferative Activities

A library of isopulegol-based β-amino acid derivatives has been developed from commercially-available (-)-isopulegol. Michael addition of primary and secondary amines towards α,β-unsaturated γ-lactones was accomplished resulting in β-aminolactones in highly-stereoselective reactions. Ring-opening of β-aminolactones with different amines furnished excellent yields of β-aminoamides. Moreover, the applicability of aminolactones in peptide synthesis was examined by opening the lactone ring with α- and β-aminoesters, providing dipeptides as promising chiral substrates for the synthesis of foldamers. The antiproliferative activities of β-aminolactones and β-aminoamides were explored, and the structure-activity relationships were studied from the aspects of the stereochemistry of the monoterpene ring and the substituent effects on the β-aminoamide ring system. The N-unsubstituted (-)-isopulegol-based β-aminoamides exhibited considerable antiproliferative activity against a panel of human adherent cancer cell lines (HeLa, MCF7 and MDA-MB-231).

scholarly journals Applications of "planar-chiral" heterocycles in asymmetric catalysis

2001 ◽  
Vol 73 (7) ◽  
pp. 1113-1116 ◽  
Author(s):  
Gregory C. Fu
Keyword(s):  
Asymmetric Catalysis ◽  
Ring Opening ◽  
Kinetic Resolution ◽  
Ring Expansion ◽  
Chiral Ligands ◽  
Primary Amines ◽  
Allylic Alcohols ◽  
Catalyzed Reactions ◽  
Metal Catalyzed ◽  
Derivatives Of

Planar-chiral derivatives of pyridine function as efficient catalysts for processes such as the kinetic resolution of primary amines and the desymmetrization/ring-opening of meso epoxides. Planar-chiral pyrrolyl and phospholyl derivatives serve as effective chiral ligands for a range of metal-catalyzed reactions, including the copper-catalyzed ring-expansion of oxetanes and the rhodium-catalyzed isomerization of allylic alcohols.

scholarly journals Synthesis and Investigation of Pinane-Based Chiral Tridentate Ligands in the Asymmetric Addition of Diethylzinc to Aldehydes

Catalysts ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 474
Author(s):  
Mounir Raji ◽  
Tam Minh Le ◽  
Ferenc Fülöp ◽  
Zsolt Szakonyi
Keyword(s):  
Molecular Modeling ◽  
Ring Opening ◽  
Benzyl Bromide ◽  
Allylic Alcohol ◽  
Ring Closure ◽  
Reaction Pathways ◽  
Secondary Amines ◽  
Tridentate Ligands ◽  
Stereoselective Epoxidation ◽  
Carbonyl Function

A library of pinane-based chiral aminodiols, derived from natural (−)-β-pinene, were prepared and applied as chiral catalysts in the addition of diethylzinc to aldehydes. (−)-β-Pinene was reacted to provide 3-methylenenopinone, followed by a reduction of the carbonyl function to give a key allylic alcohol intermediate. Stereoselective epoxidation of the latter and subsequent ring opening of the resulting oxirane with primary and secondary amines afforded aminodiols. The regioselectivity of the ring closure of the N-substituted secondary aminodiols with formaldehyde was examined and exclusive formation of oxazolidines was observed. Treatment of the allylic alcohol with benzyl bromide provided the corresponding O-benzyl derivative, which was transformed into O-benzyl aminodiols by aminolysis. Ring closure of the N-isopropyl aminodiol derivative with formaldehyde resulted in spirooxazolidine. The obtained potential catalysts were applied in the reaction of both aromatic and aliphatic aldehydes to diethylzinc providing moderate to good enantioselectivities (up to 87% ee). Through the use of molecular modeling at an ab initio level, this phenomenon was interpreted in terms of competing reaction pathways. Molecular modeling at the RHF/LANL2DZ level of theory was successfully applied for interpretation of the stereochemical outcome of the reactions leading to display excellent (R) enantioselectivity in the examined transformation.

Stereoselective Synthesis 1 Stereoselective Reactions of Carbon—Carbon Double Bonds

2011 ◽  
Author(s):  
J. G. de Vries ◽  
K. Muñiz ◽  
G. Franciò ◽  
W. Leitner ◽  
P. L. Alsters ◽  
...  
Keyword(s):  
Stereoselective Synthesis ◽  
Double Bonds ◽  
Stereoselective Reactions

Substituent Effects in Mechanochemical Allowed and Forbidden Cyclobutene Ring-Opening Reactions

2021 ◽  
Author(s):  
Cameron L. Brown ◽  
Brandon H. Bowser ◽  
Jan Meisner ◽  
Tatiana B. Kouznetsova ◽  
Stefan Seritan ◽  
...  
Keyword(s):  
Ring Opening ◽  
Substituent Effects ◽  
Ring Opening Reactions

scholarly journals Stereoselective Synthesis of Tetraalkyl Cyclobutene-1,2,3,4-tetracarboxylates. Synthesis of Tetraalkyl (Z,Z)-Buta-1,3-diene-1,2,3,4-tetracarboxylates

1999 ◽  
Vol 23 (8) ◽  
pp. 512-513
Author(s):  
Issa Yavari ◽  
Farahnaz Nourmohammadian
Keyword(s):  
Ring Opening ◽  
Wittig Reaction ◽  
Stereoselective Synthesis ◽  
Intramolecular Wittig Reaction ◽  
Ring Opening Reactions ◽  
Boiling Toluene

Tetraalkyl cyclobutene-1,2,3,4-tetracarboxylates, prepared by intramolecular Wittig reaction between a vinylphosphonium salt and diethyl 2-oxobutanedioate, undergo electrocyclic ring-opening reactions, in boiling toluene, to produce highly electron-deficient 1,3-dienes.

scholarly journals Novel Acetohydrazide Pyrazole Derivatives: Design, Synthesis, Characterization and Antimicrobial Activity

2019 ◽  
Vol 31 (12) ◽  
pp. 2740-2744
Author(s):  
Anil Verma ◽  
Vinod Kumar ◽  
Ramesh Kataria ◽  
Joginder Singh
Keyword(s):  
Mass Spectrometry ◽  
Antimicrobial Activity ◽  
Antimicrobial Agents ◽  
Antimicrobial Activities ◽  
Pyrazole Derivatives ◽  
Reaction Conditions ◽  
Design Synthesis ◽  
Structure Activity ◽  
Electron Withdrawing Group ◽  
Sar Study

Eleven acetohydrazide linked pyrazole derivatives were designed and synthesized via condensation of acetohyadrazide with different substituted formyl pyrazole derivatives under mild reaction conditions. Synthesized compounds were characterized on the basis of IR, NMR (1H & 13C) and mass spectrometry. The antimicrobial activities of all the compounds were screened against four bacterial and two fungal strains. Among the synthesized compounds, three compounds viz. 6b, 6c and 6d were found as efficient antimicrobial agents in reference to the standard drugs viz. ciprofloxacin and amphotericin-B. Further, structure-activity relationship (SAR) study revealed that electron-withdrawing group enhances the antimicrobial potential of synthesized derivatives as compared to other groups present in the ring. Hence, among compounds 6b-c, compound 6d could be explored further against other microbes to prove its vitality.

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