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Journal ArticleDOI

Benzopyrans. 31. Reaction of 1,1-diacetyl-2-(6-methyl-4-oxo-4H-1-benzopyran-3-yl)ethylene with phenyldiazomethane

07 May 1993-Tetrahedron (Pergamon)-Vol. 49, Iss: 19, pp 4135-4140
Abstract: Phenyldiazomethane yields with the title alkene 1 a mixture of the trans -cyclopropane 6 , benzopyran 8 , pyrazole 9 , and cis -dihydrofuran 12 . The cyclopropane 6 thermally rearranges to a trans -dihydrofuran tentatively assigned the structure 4 .
Topics: Benzopyran (58%), Benzopyrans (57%), Enone (55%), Cyclopropane (54%), Pyrazole (53%)
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Abstract: The Chemistry and application of the title aldehyde and some simple derivatives thereof are reviewed.

40 citations

Journal ArticleDOI
09 Nov 2015-Chemical Science
TL;DR: TBA[Fe] catalyzes the rearrangement of vinyl and arylcyclopropanes under thermal or photochemical conditions.
Abstract: The base metal complex Bu4N[Fe(CO)3(NO)] (TBA[Fe]) catalyzes the rearrangement of vinyl and arylcyclopropanes both under thermal or photochemical conditions to give the corresponding vinyl or aryldihydrofurans in good to excellent yields. Under photochemical conditions the reaction is performed at room temperature. Spectroscopic investigations show that the metal carbonyl catalyst is not decarbonylated. The best performance was observed at a wavelength of 415 nm. icMRCI+Q analysis of the excited singlet and triplet states of the [Fe(CO)3(NO)] anion was performed and used to calculate the vertical excitation energies which are in good agreement with the experimental data. CASSCF analysis indicates that the Fe center in all excited states of the ferrate becomes more electrophilic while adopting a distorted tetrahedral configuration. Both aspects have a positive synergistic effect on the formation of the initial π-complex with the incoming organic substrate.

39 citations

Journal ArticleDOI
Abstract: Condensation 4-oxo-4H-chromene-3-carboxaldehydes (1a,b) with acid hydrazine-carbodithioic acid and/or thiocarbohydrazide afforded hydrazonecarbodithioic acid 2, monothiocarbohydrazone 3a,b and bisthiocarbohydrazone 4, respectively. Heterocyclization of 2–4 via reaction with oxygen, sulfur and/or halogen reagents in different media yielded pyridazinethione 5; 1,3-thiazoles 7; pyrazoles 9–12; 1,2,4-thiadiazoles 8,13,14, and 23; 1,2,4-triazolethiones 15–17; 1,2,4-triazinethiones 18–22; imidazolethione 24 and pyrimidinethione 25 derivatives. Antifungal activity was screened for some the new synthesized compounds. Formulations of all products have been deduced by elemental analysis and spectral data (IR, 1H NMR and Mass spectroscopy).

27 citations

Journal ArticleDOI
Abstract: Acceptor-substituted vinyl- (VCP) and arylcyclopropanes (ACP) are reactive substrates for nucleophilic activation using Bu4N[Fe(CO)3(NO)] (TBA[Fe]). In this account, the application of this catalytic strategy in traceless allylic substitution, [3+2]-cycloaddition, and Cloke-Wilson rearrangement will be presented. Additional information, derived from detailed spectroscopic and theoretical investigations, is discussed. These results not only lead to a deeper understanding of the reactivity of the catalyst in VCP and ACP activation, but also set the stage for a new type of catalyst activation using photochemical irradiation at 415 nm.

9 citations

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Journal ArticleDOI
Abstract: The thermal and photochemical conversion of (1R*,2R*,3S*), (1S*,2R*,3S*), and (1S*,2R*,3R*)-1-acetyl-1,2-dimethyl-3-phenylcyclopropane (1, 2, and 3) to cis- and trans-2,3,4-trimethyl-5-phenyl-4,5-d...

26 citations