scholarly journals Stereoselective synthesis and transformation of pinane-based 2-amino-1,3-diols

2021 ◽  
Vol 17 ◽  
pp. 983-990
Author(s):  
Ákos Bajtel ◽  
Mounir Raji ◽  
Matti Haukka ◽  
Ferenc Fülöp ◽  
Zsolt Szakonyi
Keyword(s):  
Alkaline Hydrolysis ◽  
Stereoselective Synthesis ◽  
2D Nmr ◽  
Ring Closure ◽  
Spectroscopic Techniques ◽  
Reductive Alkylation ◽  
X Ray ◽  
Relative Stereochemistry ◽  
Hydrolysis Of

A library of pinane-based 2-amino-1,3-diols was synthesised in a stereoselective manner. Isopinocarveol prepared from (−)-α-pinene was converted into condensed oxazolidin-2-one in two steps by carbamate formation followed by a stereoselective aminohydroxylation process. The relative stereochemistry of the pinane-fused oxazolidin-2-one was determined by 2D NMR and X-ray spectroscopic techniques. The regioisomeric spiro-oxazolidin-2-one was prepared in a similar way starting from the commercially available (1R)-(−)-myrtenol (10). The reduction or alkaline hydrolysis of the oxazolidines, followed by reductive alkylation resulted in primary and secondary 2-amino-1,3-diols, which underwent a regioselective ring closure with formaldehyde or benzaldehyde delivering pinane-condensed oxazolidines. During the preparation of 2-phenyliminooxazolidine, an interesting ring–ring tautomerism was observed in CDCl3.

scholarly journals Synthesis and transformation of sphingosine analogue pinane-based 2-amino-1,3-diols

2021 ◽  
Author(s):  
Ákos Bajtel ◽  
Mounir Raji ◽  
Matti Haukka ◽  
Ferenc Fülöp ◽  
Zsolt Szakonyi
Keyword(s):  
Alkaline Hydrolysis ◽  
2D Nmr ◽  
Ring Closure ◽  
Biologically Active ◽  
Reductive Alkylation ◽  
X Ray ◽  
Relative Stereochemistry ◽  
Hydrolysis Of

A library of pinane-based 2-amino-1,3-diols, analogues of biologically active sphingosine, was synthesised in a stereoselective manner. Isopinocarveol prepared from (–)-α-pinene was converted to condensed oxazolidin-2-one in two steps by carbamate formation followed by a stereoselective aminohydroxylation process. The relative stereochemistry of the pinane-fused oxazolidin-2-one was determined by 2D NMR and X-ray technics. The regioisomeric spiro-oxazolidin-2-one was prepared in a similar way starting from commercially available (1R)-(–)-myrtenol. Reduction or alkaline hydrolysis of oxazolidines followed by reductive alkylation resulted in primary and secondary 2-amino-1,3-diols, which underwent regioselective ring closure with formaldehyde or benzaldehyde delivering pinane-condensed oxazolidines. During the preparation of 2-phenyliminooxazolidine, an interesting ring–ring tautomerism was observed in CDCl3.

scholarly journals Additional New Tetracyclic Tetraterpenoid: Methyl Tortuoate D from Soft Coral Sarcophyton tortuosum

2009 ◽  
Vol 4 (9) ◽  
pp. 1934578X0900400 ◽  
Author(s):  
Wen-Jian Lan ◽  
Shou-Liang Wang ◽  
Hou-Jin Li
Keyword(s):  
Mass Spectrometry ◽  
South China Sea ◽  
Electrospray Ionization ◽  
South China ◽  
Soft Coral ◽  
2D Nmr ◽  
Ionization Mass ◽  
Spectroscopic Techniques ◽  
Direct Infusion ◽  
Relative Stereochemistry

Under the guidance of chemical prescreening by direct infusion electrospray ionization mass spectrometry (DI ESI-MS), a new tetracyclic tetraterpenoid, methyl tortuoate D (1) was isolated from the soft coral Sarcophyton tortuosum collected from the South China Sea. Its structure and relative stereochemistry were established by MS, and 1D- and 2D-NMR spectroscopic techniques.

Stereoselective Synthesis of Spiro-α-methylene-γ-lactams via Chiral Quaternary 3-Aminooxindole Adducts Accessed by Zn-Mediated Allylation of Sulfinyl Ketimines

Synthesis ◽  
2020 ◽  
Vol 52 (17) ◽  
pp. 2551-2562 ◽  
Author(s):  
Ravi P. Singh ◽  
V. U. Bhaskara Rao ◽  
Shashank Singh ◽  
Krishna N. Tripathi
Keyword(s):  
Single Crystal ◽  
Structure Analysis ◽  
Efficient Method ◽  
Good Yield ◽  
Stereoselective Synthesis ◽  
High Selectivity ◽  
X Ray ◽  
Relative Stereochemistry ◽  
Very High

An efficient method for the stereoselective synthesis of α-methylene-γ-lactams via quaternary 3-aminooxindoles with very high selectivity (up to 98% ee) is described. The methodology leads to the construction of sterically congested chiral quaternary 3-aminooxindole adducts in good yield and with moderate to excellent diastereoselectivity (dr up to 95:5). The relative stereochemistry of the chiral quaternary 3-aminooxindoles adduct and the spiro-α-methylene-γ-lactam was confirmed to be syn by single-crystal X-ray structure analysis. Furthermore, the α-methylene-γ-lactam was successfully transformed into a range of chiral synthons.

scholarly journals A New Pyrrolidine Derivative and Steroids from an Algicolous Gibberella zeae Strain

2011 ◽  
Vol 6 (9) ◽  
pp. 1934578X1100600 ◽  
Author(s):  
Xiang-Hong Liu ◽  
Xiao-Zhen Tang ◽  
Feng-Ping Miao ◽  
Nai-Yun Ji
Keyword(s):  
Cell Lines ◽  
Green Alga ◽  
Endophytic Fungus ◽  
2D Nmr ◽  
Gibberella Zeae ◽  
Spectroscopic Techniques ◽  
Codium Fragile ◽  
Relative Stereochemistry ◽  
Marine Green Alga

A new pyrrolidine derivative, 3-hydroxy-5-(hydroxymethyl)-4-(4′-hydroxyphenoxy)pyrrolidin-2-one (1), and eight known steroids, (22 E,24 R)-7β,8β-epoxy-3β,5α,9α-trihydroxyergosta-22-en-6-one (2, a reassigned structure of (22 E,24 R)-5α,6α-epoxy-3β,8β,14α-trihydroxyergosta-22-en-7-one), (22 E,24 R)-3β,5α,9α-trihydroxyergosta-7,22-dien-6-one (3), (22 E,24 R)-3β,5α-dihydroxyergosta-7,22-dien-6-one (4), (22 E,24 R)-ergosta-7,22-dien-3β,5α,6β-triol (5), (22 E,24 R)-ergosta-5,22-dien-3β-ol (6), (22 E,24 R)-5α,8α-epidioxyergosta-6,22-dien-3β-ol (7), (22 E,24 R)-5α,8α-epidioxyergosta-6,9(11),22-trien-3β-ol (8), and (22 E,24 R)-1(10→6)- abeo-ergosta-5,7,9,22-tetraen-3α-ol (9), were isolated from the cultures of Gibberella zeae, an endophytic fungus isolated from the marine green alga Codium fragile. Their structures and relative stereochemistry were elucidated by 1D, 2D NMR and mass spectroscopic techniques. Compound 1 showed cytotoxicity against A-549 and BEL-7402 cell lines.

Enantioselective ester hydrolyses using Rhizopusnigricans: stereoselective synthesis and absolute stereochemistry of (−)-cis- and (−)-trans-1-hydroxy-4-methyl-1,2,3,4-tetrahydronaphthalene

1985 ◽  
Vol 63 (6) ◽  
pp. 1287-1291 ◽  
Author(s):  
Masaji Kasai ◽  
Herman Ziffer ◽  
J. V. Silverton
Keyword(s):  
Stereoselective Synthesis ◽  
Chiral Alcohols ◽  
Enantioselective Hydrolysis ◽  
Chemical Transformations ◽  
X Ray ◽  
X Ray Crystallography ◽  
Cis And Trans ◽  
Hydrolysis Of ◽  
Absolute Stereochemistry

Enantioselective hydrolysis of racemic acetates of cis- and trans-1-hydroxy-4-methyl-1,2,3,4-tetrahydronaphthalene using Rhizopusnigricans yields chiral alcohols. The absolutestereochemistry of these compounds, and that of a key intermediate in their stereoselective synthesis, r-1-hydroxy-2,t-bromo-4,c-methyl-1,2,3,4-tetrahydronaphthalene, were determined by chemical transformations to 1-oxo-4-methyl-1,2,3,4-tetrahydronaphthalene of known absolute stereochemistry. The relativestereochemistry of the acetate of the key intermediate was established by X-ray crystallography.

scholarly journals Synthesis and structural analysis of polynuclear silver(I) complexes with 4,7-phenanthroline

2019 ◽  
Vol 84 (7) ◽  
pp. 689-699 ◽  
Author(s):  
Ivana Stanojevic ◽  
Nada Savic ◽  
Aurélien Crochet ◽  
Katharina Fromm ◽  
Milos Djuran ◽  
...  
Keyword(s):  
Solid State ◽  
Room Temperature ◽  
Volume Ratio ◽  
Spectroscopic Techniques ◽  
X Ray Diffraction ◽  
X Ray ◽  
Bridging Ligand ◽  
Coordination Sites ◽  
Hydrolysis Of

New polynuclear silver(I) complexes, [Ag(CF3SO3)(4,7-phen)(CH3CN)]n (1) and [Ag(PO2F2)(4,7-phen)]n (2), were synthesized by the reaction of 4,7-phenanthroline (4,7-phen) and the corresponding AgX salt (X = CF3SO3 - and PF6 -) in 1:2 mole ratio, respectively, in methanol/acetone (1:1 volume ratio) at room temperature. The characterization of the complexes was established on the basis of elemental microanalysis, IR and NMR (1H and 13C) spectroscopic techniques, while their crystal structures were determined by single-crystal X-ray diffraction analysis. The results of spectroscopic and crystallographic analyses revealed that in these complexes, 4,7-phen behaves as a bridging ligand between two metal ions, while the remaining coordination sites of the Ag(I) ions are occupied by the oxygen atom of CF3SO3 - and an acetonitrile nitrogen atom in 1 or by two oxygen atoms from two PO2F2 -, formed after hydrolysis of PF6 -, in 2. In the solid state, both complexes are coordination polymers in which the geometry around the Ag(I) ions is distorted tetrahedral.

An expeditious synthesis of (±)-decahydro-5H-dipyrrolo [1,2-a:1',2'-c]pyrimidine-5-carbonitrile: a formal synthesis of (±)-tetraponerines-1, -2, -5, and -6

2000 ◽  
Vol 78 (7) ◽  
pp. 1030-1034
Author(s):  
M Plehiers ◽  
S Heilporn ◽  
D Ekelmans ◽  
S Leclercq ◽  
M Sangermano ◽  
...  
Keyword(s):  
Stereoselective Synthesis ◽  
Diethyl Malonate ◽  
Reductive Alkylation ◽  
One Pot ◽  
Formal Synthesis ◽  
Multistep Process ◽  
Practical Synthesis ◽  
Hydrolysis Of

A short and practical synthesis of (±)-decahydro-5H-dipyrrolo[1,2-a:1',2'-c]pyrimidine-5-carbonitrile (17), a pivotal intermediate in the synthesis of (±)-tetraponerines-1 (5), -2 (6), -5 (7), and -6 (8), in three steps and 24% overall yield, from simple and inexpensive starting materials, is reported. The key step of our synthesis is a one pot stereoselective multistep process, whereupon two molecules of Δ1-pyrroline (9) react with diethyl malonate (10) to afford the tricyclic lactam ester 13, possessing the tetraponerine skeleton. Hydrolysis of the carboethoxy group of 13 followed by decarboxylation yields lactam 15, which is converted into α-aminonitrile 17. Our fruitless efforts to transform lactam 15 into the tetraponerines through reductive alkylation are also discussed.Key words: alkaloids, tetraponerines, stereoselective synthesis, Robinson-Schöpf reaction, lactams, ants.

scholarly journals Single Crystal X-ray Diffraction, Spectroscopic and Mass Spectrometric Studies of Furanocoumarin Peucedanin

2014 ◽  
Vol 9 (1) ◽  
pp. 1934578X1400900
Author(s):  
Magdalena Bartnik ◽  
Marta Arczewska ◽  
Anna A. Hoser ◽  
Tomasz Mroczek ◽  
Daniel M. Kamiński ◽  
...  
Keyword(s):  
Single Crystal ◽  
Crystal Lattice ◽  
2D Nmr ◽  
Unit Cell ◽  
Spectroscopic Techniques ◽  
Fragmentation Pattern ◽  
X Ray Diffraction ◽  
X Ray ◽  
Single Column ◽  
Biological Tests

The structure of peucedanin, isolated from Peucedanum tauricum Bieb. (Apiaceae), has been established using single crystal X-ray diffraction. This furanocoumarin isolated from the light petroleum extract of P. tauricum fruits was characterized by high resolution EI-MS, sATR-FTIR and 2D NMR spectroscopic techniques. The EI-MS showed the typical fragmentation pattern of methoxyfuranocoumarins. Extensive 1D (1H and 13C) as well as 2D NMR data enabled complete assignment of the carbon atoms in the peucedanin molecule. The FTIR data confirms intermolecular hydrogen bonding between peucedanin molecules in polar solvents. Peucedanin crystallises in the R-3 space group from the trigonal system with one molecule in the asymmetric part of the unit cell. The crystal lattice of peucedanin consists of the molecules arranged in separate columns. They are related by two fold screw axes and centres of symmetry. Interestingly, peucedanin columns form two channels per unit cell with a diameter of 7.5Å going through the crystal lattice in the Z-direction. These channels are filled with disordered water molecules, which are surrounded by hydrophobic methyl groups and are located exactly at the centres of the channels. The peucedanin molecules are stacked in a single column with the opposite orientation of the neighbouring molecules. These results could be interesting in further application of this molecule, for example in biological tests of its activity.

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