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.

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.

Intramolecular Cycloaddition Approach to Fused Pyrazoles: Access to 4,5-Dihydro-2H-pyrazolo[4,3-c]quinolines, 2,8-Dihydroindeno[2,1-c]pyrazoles, and 4,5-Dihydro-2H-benzo[e]indazoles

Synthesis ◽  
2017 ◽  
Vol 50 (07) ◽  
pp. 1511-1520 ◽  
Author(s):  
Chinmay Chowdhury ◽  
Moumita Jash ◽  
Bimolendu Das ◽  
Suparna Sen
Keyword(s):  
Reaction Mechanism ◽  
Dft Calculations ◽  
Functional Groups ◽  
Efficient Method ◽  
Diazo Compound ◽  
Dipolar Cycloaddition ◽  
Reaction Sequence ◽  
Intramolecular Cycloaddition ◽  
Aromatic Substrate ◽  
Fused Pyrazoles

A straightforward and efficient method for the synthesis of pyrazoles fused with 1,2,3,4-tetrahydroquinoline, 2,3-dihydro-1H-indene­, or 1,2,3,4-tetrahydronaphthalene involves the formation of the tosylhydrazone from an aromatic substrate carrying aldehyde and acetylenic functionalities at appropriate positions, followed by base-promoted generation of the diazo compound and subsequent intramolecular 1,3-dipolar cycloaddition. A number of functional groups were found to be compatible for this reaction sequence and yields were moderate to very good (44–95%). A plausible reaction mechanism supported by DFT calculations has been provided to explain the formation of products.

An unusual tert-butylamine mediated conversion of 6-aryl-7-formyl-2,4,5,8-tetrahydro-1,3-dioxa-5-azocines to 1,2,3,6-tetrahydropyrimidine derivatives

1990 ◽  
Vol 55 (10) ◽  
pp. 2502-2509 ◽  
Author(s):  
Ladislav Štibrányi ◽  
Lubor Fišera ◽  
Rastislav Káčer ◽  
Vladimír Oremus ◽  
Martina Mihulová
Keyword(s):  
Membered Ring ◽  
Dipolar Cycloaddition ◽  
Reaction Sequence ◽  
Pyrimidine Derivatives ◽  
Reaction Conditions ◽  
Photochemical Rearrangement ◽  
Tert Butylamine

An unexpected contraction of the 8-membered ring to a 6-membered one occurring when 6-aryl-7-formyl-2,4,5,8-tetrahydro-1,3-dioxa-5-azocines II were treated with tert-butylamine afforded 4-aryl-5-formyl-1-(1,1-dimethylethyl)-1,2,3,6-tetrahydropyrimidines III. Reaction conditions for the photorearrangement of chlorophenyl-substituted condensed isoxazolines I to II were worked out. The reaction sequence: 1,3-dipolar cycloaddition, photochemical rearrangement, treatment with tert-butylamine constitutes a new route to pyrimidine derivatives from 2H,4H,7H-1,3-dioxepine.

An unusual effect of exo-endo configuration on the quantum yield Φ of photochemical rearrangement of 4-R-substituted 8-phenyl-3,5,10-trioxa-9-azabicyclo-[5,3,0]-8-decenes

1986 ◽  
Vol 51 (10) ◽  
pp. 2158-2166 ◽  
Author(s):  
Lubor Fišera ◽  
Vladimír Oremus ◽  
Hans-Joachim Timpe ◽  
Ladislav Štibrányi ◽  
Peter Zálupský
Keyword(s):  
Quantum Yield ◽  
Dipolar Cycloaddition ◽  
Tert Butyl ◽  
Photochemical Rearrangement ◽  
Unusual Effect ◽  
Derivatives Of

The dependence has been found of the quantum yield Φ of photochemical rearrangement of the title compounds (where R means ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, 2-furyl, 2-thienyl) on the exo(I) or endo (II) arrangement of the R substituent. The endo derivatives exhibit higher Φ values (0.020-0.041) than the exo derivatives (0.007-0.019). The photochemical rearrangement gives the derivatives of 2-R-6-phenyl-7-formyl-2,4,5,8-tetrahydro-1,3-dioxa-5-azocine as the single products in good yields. The 2-furyl derivative gives polymeric products. The title compounds have been prepared by 1,3-dipolar cycloaddition of benzenenitriloxide to the respective substituted 1,3-dioxep-5-enes.

1,3-Dipolar cycloaddition of N-allyl substituted polycyclic derivatives of isoindole-1,3-dione with nitrones and nitrile oxides: An experimental and theoretical investigation

Tetrahedron ◽  
2020 ◽  
Vol 76 (15) ◽  
pp. 131104 ◽  
Author(s):  
Mariia M. Efremova ◽  
Alexander P. Molchanov ◽  
Alexander S. Novikov ◽  
Galina L. Starova ◽  
Anna A. Muryleva ◽  
...  
Keyword(s):  
Theoretical Investigation ◽  
Dipolar Cycloaddition ◽  
Nitrile Oxides ◽  
Derivatives Of

Preparation and photochemistry of 3-cyanosubstituted condensed isoxazolines containing an oxygen atom

1987 ◽  
Vol 52 (7) ◽  
pp. 1773-1779 ◽  
Author(s):  
Vladimír Oremus ◽  
Lubor Fišera ◽  
Ladislav Štibrányi
Keyword(s):  
Oxygen Atom ◽  
Quantum Yields ◽  
Dipolar Cycloaddition ◽  
Derivatives Of

The 1,3-dipolar cycloaddition of cyanonitrile oxide to 2,3- and 2,5-dihydrofurane, 7-oxabicyclo[2,2,1]-2-heptene and derivatives of 1,3-dioxep-5-ene is described. The condensed isoxazolines Ia, IIIa, Va, Vc, Vd thus prepared are rearranged on irradiation into cyanosubstituted heterocyclic enaminoaldehydes IIa, IVa, VIa, VIc. The quantum yields of the photorearrangement of cyanoderivatives are higher than those of the phenyl derivatives, being within the limits from 0·068 to 0·19. The reaction of II with hydrazine gives the derivative IX of oxazino[4,5-d]pyridazine.

Synthesis of Novel 1,2,3-Triazole Derivatives of Isocoumarins and 3,4-Dihydroisocoumarin with Potential Antiplasmodial Activity In Vitro

2020 ◽  
Vol 16 ◽  
Author(s):  
Lucas da Silva Santos ◽  
Matheus Fillipe Langanke de Carvalho ◽  
Ana Claudia de Souza Pinto ◽  
Amanda Luisa da Fonseca ◽  
Julio César Dias Lopes ◽  
...  
Keyword(s):  
Triazole Ring ◽  
Antiplasmodial Activity ◽  
World Health ◽  
Dipolar Cycloaddition ◽  
Terminal Alkynes ◽  
The World ◽  
Ic50 Values ◽  
Derivatives Of ◽  
Active Substances

Background: Malaria greatly affects the world health, having caused more than 228 million cases only in 2018. The emergence of drug resistance is one of the main problems in its treatment, demonstrating the urge for the development of new antimalarial drugs. Objective: Synthesis and in vitro antiplasmodial evaluation of triazole compounds derived from isocoumarins and a 3,4- dihydroisocoumarin. Method: The compounds were synthesized in 4 to 6-step reactions with the formation of the triazole ring via the Copper(I)-catalyzed 1,3-dipolar cycloaddition between isocoumarin or 3,4-dihydroisocoumarin azides and terminal alkynes. This key reaction provided compounds with an unprecedented connection of isocoumarin or 3,4-dihydroisocoumarin and the 1,2,3-triazole ring. The products were tested for their antiplasmodial activity against a Plasmodium falciparum chloroquine resistant and sensitive strains (W2 and 3D7, respectively). Results: Thirty-one substances were efficiently obtained by the proposed routes with an overall yield of 25-53%. The active substances in the antiplasmodial test displayed IC50 values ranging from 0.68-2.89 μM and 0.85-2.07 μM against W2 and 3D7 strains, respectively.

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.

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