scholarly journals Synthesis of novel spiro-isoxazoline and spiro-isoxazolidine derivatives of tomentosin

RSC Advances ◽  
2017 ◽  
Vol 7 (11) ◽  
pp. 6523-6529 ◽  
Author(s):  
Mohamed Zaki ◽  
Abdelouahd Oukhrib ◽  
Mohamed Akssira ◽  
Sabine Berteina-Raboin
Keyword(s):  
Double Bond ◽  
Dipolar Cycloaddition ◽  
Exocyclic Double Bond ◽  
Enantiomerically Pure ◽  
Nitrile Oxides ◽  
Dittrichia Viscosa ◽  
Derivatives Of

A series of novel enantiomerically pure spiro-(isoxazolidines/isoxazolines) were synthesized regioselectively by 1,3-dipolar cycloaddition using nitrones and nitrile oxides, on the exocyclic double bond of tomentosin extracted from Dittrichia viscosa.

Synthesis of Spiro-Isoxazolidine Derivatives of Methyl α-Isocostate

2019 ◽  
Vol 9 (4) ◽  
pp. 262-267
Author(s):  
Mohamed Zaki ◽  
Abdelouahd Oukhrib ◽  
Mohammed Loubidi ◽  
Ahmed El Hakmaoui ◽  
Marie-Aude Hiebel ◽  
...  
Keyword(s):  
Natural Products ◽  
Therapeutic Agents ◽  
Spiro Compounds ◽  
Dipolar Cycloaddition ◽  
Exocyclic Double Bond ◽  
Plant Resources ◽  
Enantiomerically Pure ◽  
Dittrichia Viscosa ◽  
Spiro Derivatives ◽  
Derivatives Of

Background: In recent decades, natural products are an important source of chemotherapeutics as more than half of the effective cancer drugs can be traced to natural origins. Objective: Moreover, the modification of natural products is one of the most common and fruitful approaches to obtain novel therapeutic agents in medicinal chemistry. Method: Continuing with a research project based on the support of Moroccan plant resources. we report herein the use of α-isocostic acid extracted in enantiomerically pure form from Dittrichia viscosa as a convenient starting material for the synthesis of new eudesmane derivatives. Results: Novel spiro derivatives with a natural scaffold were prepared. Spiro-isoxazolidine derivatives were generated on the exocyclic double bond adjacent to the ester α,β-unsaturated function by 1,3-dipolar cycloaddition of methyl α-isocostate 1 derived from sesquiterpenic isocostic acid, with nitrones 2. Conclusion: This procedure allowed us to generate enantiomerically pure spiro compounds in one diastereoisomer form with a limited number of steps. These compounds were fully characterized by spectroscopic methods.

Derivatives of tetrahydro-2H-pyridine from photorearranged cycloadducts of nitrile oxides

1990 ◽  
Vol 55 (2) ◽  
pp. 512-523 ◽  
Author(s):  
Lubor Fišera ◽  
Vladimír Ondruš ◽  
Hans-Joachim Timpe
Keyword(s):  
Reaction Mechanism ◽  
Double Bond ◽  
Quantum Yields ◽  
Dipolar Cycloaddition ◽  
Mercury Lamp ◽  
Reaction Sequence ◽  
Nitrile Oxides ◽  
Photochemical Rearrangement ◽  
Benzene Rings ◽  
Derivatives Of

1,3-Dipolar cycloaddition of methoxycarbonylnitrile, furannitrile and substituted benzene nitrile oxides (X = 4-CH3, 4-OCH3, 3-OCH3, 4-Cl, 3-Cl, 2,4-diCl, 4-F) to dimethyl 7-(diphenylmethylene)bicyclo[2.2.1]hept-2-ene-5,6-dicarboxylate (XII) led exclusively to exo cycloadducts IV, on irradiation with a low-pressure mercury lamp afforded the required 4-substituted derivatives of dimethyl 2,2-diphenyl-5-formyl-3-azabicyclo[4.3.0]nona-4,9-diene-7,8-dicarboxylate (XI) as sole products. Selectivity of the photorearrangement of isoxazolines IV to enaminoaldehydes XI is due to a stabilization of the biradical VII by the overlap of the radical-electron with π-electrons of the C=C double bond and by two benzene rings. Quantum yields of the photorearrangement, established from the deficit of the starting IV, were found to be greater than those for the analogous oxabicyclic derivatives XVI. The reaction mechanism is proposed and the dependence on various solvents is pointed out; this reaction sequence, viz. the 1,3-dipolar cycloaddition followed by a photochemical rearrangement provides a new method for obtaining derivatives of tetrahydro-2H-pyridine from the well available cyclopentadiene.

π-Facial Selectivity in 1,3-Dipolar Cycloaddition Reactions of α-Methylidene-γ-lactone Substituted by 4-Methyl-2,6,7-trioxabicyclo[2.2.2]octan-1-yl Group in γ-Position

2002 ◽  
Vol 67 (3) ◽  
pp. 353-364 ◽  
Author(s):  
Petr Melša ◽  
Ctibor Mazal
Keyword(s):  
Double Bond ◽  
Carboxylic Acid ◽  
Nitrile Oxide ◽  
Dipolar Cycloaddition ◽  
Cycloaddition Reactions ◽  
Enantiomerically Pure ◽  
Nitrile Imine ◽  
Facial Selectivity ◽  
Excellent Selectivity

Diastereoselectivity of 1,3-dipolar cycloaddition reactions of benzyl azide, diazomethane, a nitrile oxide and a nitrile imine to α-methylidene-γ-lactone dipolarophile was effectively controlled by a bulky γ-substituent, 4-methyl-2,6,7-trioxabicyclo[2.2.2]octan-1-yl in γ-position of the dipolarophile. The dipoles added from the less hindered face of the double bond with an excellent selectivity. Enantiomerically pure dipolarophile was prepared from the easily available (S)-5-oxotetrahydrohydrofuran-2-carboxylic acid.

Ozonolysis of Derivatives of Labda-8(17),14-dien-13-ol (Manool) and Their Conversion Into Large Ring Unsaturated Lactones

1988 ◽  
Vol 41 (5) ◽  
pp. 711 ◽  
Author(s):  
PK Grant ◽  
KL Chee ◽  
JS Prasad ◽  
MY Tho
Keyword(s):  
Double Bond ◽  
Good Yield ◽  
Spatial Relationship ◽  
Hydroxyl Group ◽  
Exocyclic Double Bond ◽  
Large Ring ◽  
Unsaturated Lactones ◽  
Derivatives Of

Dehydration of the unstable hydroperoxy ethers (4) and (6) formed on ozonolysis of the manool derivatives (2) and (5) resulted in the formation of the ten- membered unsaturated lactones (11) and (12) in good yield. The results of an investigation into the nature of the hydroxyl group and its spatial relationship to the exocyclic double bond in lactone formation are reported for other manool derivatives.

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