RESUMO
A cascade spiroannulation of 2-mercaptoquinoline-3-carbaldehydes with α,α-dicyanoalkenes as well as a cascade spiroannulation of 2-mercaptoquinoline-3-carbaldehydes aldehydes with α-bromocarbonyl compounds was investigated based on a synergistic strategy, providing a series of diverse spiro-fused heterocyclic compounds containing more different functional groups. The features of this strategy directed towards molecular complexity and diversity include step economy, mild conditions, and high bond-forming efficiency, but important polycyclic heterocyclic products, which could be transformed into potential biologically interesting heterocyclic structures.
RESUMO
Based on a novel umpolung strategy, an efficient and highly enantioselective cascade aldol/cyclization/tautomerization of the 2-(2-oxoindolin-3-yl)malononitrile to active carbonyl compounds with excellent diastereo- and enantioselectivity has been developed. Also, various enantio-enriched multifunctional dispiro[2-amino-4,5-dihydrofuran-3-carbonitrile]bisoxindoles with adjacent spiro-stereocenters were conveniently obtained by this novel methodology. Also, the dispiro[2-amino-4,5-dihydrofuran-3-carbonitrile]bisoxindoles were easily transformed into structurally complex molecules without any effect on the diastereo- and enantioselectivity.
RESUMO
An efficient, mild, and substrate/catalyst-controlled chemoselective reaction of o-isothiocyanato-(E)-cinnamaldehyde with amines has been established, producing three types of six-membered heterocycles: 2-(4H-benzo[d][1,3]thiazin-4-yl)acetaldehydes, 2-(2-thioxo-1,2,3,4-tetrahydroquinazolin-4-yl)acetaldehydes, and (E)-4-(2-methoxyvinyl)-4H-benzo[d][1,3]thiazines. The reaction scopes were quite broad and excellent yield was achieved. This method is extremely efficient and practical and can be conducted on a gram-scale with slightly inferior reactivity under catalyst-free conditions at low cost, making it an ideal alternative to existing methods.
RESUMO
A tandem Michael-Henry reaction of 2-mercaptoquinoline-3-carbaldehydes with nitroolefins using hydrogen-bonding-based cooperative organocatalysts for the highly diastereodivergent synthesis of chiral functionalized 3,4-dihydro-2H-thiopyrano[2,3-b]quinolines with three contiguous tertiary stereocenters has been developed.
RESUMO
An organocatalytic enantioselective domino α-amination/oxidative coupling/cyclization of thioamides to azodicarboxylates catalyzed by an easily available organic catalyst has been developed. The key step, oxidative coupling, is smoothly fulfilled in air. Optically active spiroannulated 1,2,3-thiadiazole derivatives are obtained with high yields and enantioselectivities for the first time.
RESUMO
An efficient, mild, and convenient method for the preparation of 2,3-dihydrothieno(2,3-b)quinolines and thieno(2,3-b)-quinolines via an unexpected domino aza-Morita-Baylis-Hillman/alkylation/aldol reaction has been developed. The plausible mechanisms for the unexpected reaction are also given.
RESUMO
A copper-catalyzed and microwave-assisted synthesis of fully substituted pyrroles has been developed. A series of pentasubstituted pyrroles, especially α-arylpyrroles, could be obtained in moderate to good yields (up to 93%) through a tandem propargylation/alkyne azacyclization/isomerization sequence from readily available ß-enamino compounds and propargyl acetates.
RESUMO
A formal thio [3+2] cyclization catalyzed by Takemoto's organocatalyst has been reported for the construction of optically active spiroannulated dihydrothiophenes in high yields with excellent regio-, chemo-, diastereo-, and enantioselectivities.
RESUMO
A series of spirooxindole tetrahydrofuran derivatives 3 were obtained in moderate to good yields via oxindole derivatives 1 and ß-arylacrylonitrile derivatives 2via base-mediated cascade [3 + 2] double Michael reactions under mild conditions and the application of this method in the synthesis of bioactive analogues, such as functionalized spirooxindole octahydrofuro[3,4-c]pyridine derivatives 4 which contain two new heterocyclic rings and two quaternary carbon centers, has also been developed. Subsequently, antifungal activities of all of the synthesized compounds were evaluated against five phytopathogenic fungi (Rhizoctonia solani, Fusarium semitectum, Alternaria solani, Valsa mali and Fusarium graminearum) using the mycelium growth rate method. The preliminary results showed that the spirooxindole octahydrofuro[3,4-c]pyridine derivative 4 showed higher growth inhibition of Valsa mali and Fusarium graminearum, than spirooxindole tetrahydrofuran derivatives 3. For example, spirooxindole octahydrofuro[3,4-c]pyridine derivative 4ab, having a bromine atom at the meta position of the benzene ring, was the best compound in inhibiting F. g. with an IC50 value of 3.31, in particular with inhibition of 4ab on F. g. being similar to that of the control cycloheximide (IC50 = 3.3 µg mL(-1)).
Assuntos
Antifúngicos/farmacologia , Compostos Heterocíclicos/farmacologia , Indóis/farmacologia , Compostos de Espiro/farmacologia , Alternaria/efeitos dos fármacos , Alternaria/crescimento & desenvolvimento , Antifúngicos/síntese química , Antifúngicos/química , Relação Dose-Resposta a Droga , Fusarium/efeitos dos fármacos , Fusarium/crescimento & desenvolvimento , Compostos Heterocíclicos/síntese química , Compostos Heterocíclicos/química , Indóis/síntese química , Indóis/química , Testes de Sensibilidade Microbiana , Oxindóis , Rhizoctonia/efeitos dos fármacos , Rhizoctonia/crescimento & desenvolvimento , Compostos de Espiro/síntese química , Compostos de Espiro/químicaRESUMO
The prohibition of antipsychotic drugs in animal foodstuffs has raised significant concerns. In this study, a novel matrix purification adsorbent comprising a polymer (polyaniline and polypyrrole)-functionalized melamine sponge (Ms) was employed for the high performance liquid chromatography-diode array detector (HPLC-DAD) detection of three phenothiazines (chlorpromazine, thioridazine, and promethazine), and a tricyclic imipramine in milk. The as-prepared functionalized Ms was characterized using scanning electron microscopy, Fourier transform infrared spectroscopy, and water contact angle measurements. Excellent linearity with a coefficient of determination (R2) of 0.999 was achieved for all drugs within the concentration range of 0.01-47.00 µg mL-1. The recoveries of the four analytes ranged from 92.1 % to 106.9 % at the three spiked levels. These results demonstrate the successful application of the proposed method for the determination of the four drugs. Cost-effective polymer-functionalized Ms is a viable alternative for matrix purification, enabling rapid determination of drug residues in diverse food samples.
Assuntos
Antipsicóticos , Leite , Triazinas , Animais , Leite/química , Cromatografia Líquida de Alta Pressão/métodos , Polímeros/química , Pirróis/análise , Extração em Fase Sólida/métodosRESUMO
A highly regio-, chemo-, diastereo- and enantioselective organocatalytic [4 + 1] annulation of 2-halo-1,3-dicarbonyl compounds with Morita-Baylis-Hillman adducts catalyzed by commercially available, low cost quinidine for the preparation of synthetically unique and medicinally multi-functionalized isoxazoline N-oxides with three stereogenic centers including adjacent quaternary and tertiary stereocenters has been developed. Notably, the unexpected product ethyl 2-((tert-butyldimethylsilyl)oxy)-2-(5,5-diacetyl-3-((methylsulfonyl)oxy)-4-phenylisoxazolidin-3-yl)acetate (8) bearing a quaternary stereocenter and two tertiary stereocenters was obtained from the undocumented 5,5-diacetyl-3-(2-ethoxy-1-hydroxy-2-oxoethyl)-4-phenyl-4,5-dihydroisoxazole 2-oxide (4ba).
Assuntos
Isoxazóis/química , Óxidos/química , Quinidina/química , Catálise , Isoxazóis/síntese química , Modelos Moleculares , Óxidos/síntese química , EstereoisomerismoRESUMO
A series of functionalized 2,3-dihydro-1,4-benzoxazines were obtained in moderate to excellent yields via domino [5 + 1] annulations of 2-halo-1,3-dicarbonyl compounds 2 with imines 1 under mild conditions and the application of this method in the synthesis of bioactive analogues, such as functionalized tetracyclic-1,4-benzoxazines which contain two new heterocyclic rings and one quaternary carbon center has also been developed.
Assuntos
Benzoxazinas/síntese química , Halogênios/química , Iminas/química , Benzoxazinas/química , Química Farmacêutica , Cristalografia por Raios X , Compostos Heterocíclicos/síntese química , Compostos Heterocíclicos/química , Estrutura MolecularRESUMO
α,α-Dicyanoolefins react with hydroxylamine to afford 2,3-dihydroisoxazoles (2,3-dihydroisoxazoles can be easily isolated by filtration) in excellent yields under mild and environmentally benign conditions. A one-pot reaction in tandem with an unexpected ring-opening of 2,3-dihydroisoxazoles has been developed as well.
Assuntos
Acrilamida/síntese química , Isoxazóis/síntese química , Água/química , Acrilamida/química , Isoxazóis/química , Estrutura MolecularRESUMO
The K(2)CO(3)-catalyzed domino reactions (Michael alkylation, Mannich alkylation, and aldol alkylation) of salicylic aldehyde derivatives (2-hydroxyaryl-α,ß-unsaturated ketones, 2-hydroxyarylnitroalkenes, 2-hydroxyarylimines, and salicylic aldehydes) and 2-halo-1,3-dicarbonyl compounds (diethyl α-bromomalonate, diethyl α-chloromalonate, ethyl 2-chloroacetoacetate, and 3-chloropentane-2,4-dione) were carried out under mild conditions to provide a series of functionalized 2,3-dihydrobenzofurans in moderate to excellent yields. The novel transformations simultaneously gave a series of clofibrate analogues, which possess various substitution patterns.
Assuntos
Benzofuranos/química , Carbonatos/química , Clofibrato/química , Potássio/química , Estrutura MolecularRESUMO
The asymmetric domino Michael-S(N)2 reaction of various 1,3-dicarbonyl compounds to α-bromonitroalkenes is described for the first time, employing readily available cinchona-derived bifunctional thioureas as organocatalysts. The novel transformations were highly regio-, chemo-, diastereo-, and enantioselective, which simultaneously gave the chiral tricyclic 2,3-dihydrofurans, bicyclic 2,3-dihydrofurans, and tetrasubstituted 2,3-dihydrofurans with two vicinal chiral carbon centers.
RESUMO
Efficient kinetic resolution of racemic 3-nitro-2H-chromenes by bifunctional thiourea afforded optically active (R)-3-nitro-2H-chromene derivatives with moderate to good enantioselectivities, which simultaneously gave the multifunctional 3,4-diphenyl-3a-nitrobenzopyrano-[3,4-c]-pyrrolidine-1,1-dicarboxylate derivatives with four vicinal chiral carbon centers.
Assuntos
Benzopiranos/química , Tioureia/química , Benzopiranos/síntese química , Catálise , Cristalografia por Raios X , Cinética , Modelos Moleculares , Estrutura Molecular , Estereoisomerismo , Tioureia/análogos & derivadosRESUMO
The diversely functionalized tricyclic tetrazoles were synthesised from readily available substrates via intramolecular 1,3-dipolar cycloaddition as the key step in good yields (53-78% yield for two steps) with high enantioselectivities (81-99% ee).
RESUMO
The one-pot synthesis of multisubstituted pyrazole derivatives was achieved via catalyst-free 1,3-dipolar cycloaddition of ethyl diazoacetate and nitroalkenes as the key step and elimination of the leaving group (NO(2) or Br) followed by intramolecular proton transfer with satisfactory yields.
Assuntos
Alcenos/química , Compostos de Diazônio/química , Pirazóis/síntese química , Catálise , Pirazóis/químicaRESUMO
The title compound, C(10)H(12)N(2)O(3), adopts a trans configuration with respect to the C=N bond. The dihedral angle between the benzene ring and the hydrazine carboxylic acid plane is 8.29â (7)°. Mol-ecules are linked into a three-dimensional network by N-Hâ¯O, O-Hâ¯O, O-Hâ¯N hydrogen bonds and C-Hâ¯π inter-actions.
RESUMO
The mol-ecule of the title compound, C(12)H(16)N(2)O(3), adopts a trans configuration with respect to the C=N bond. The dihedral angle between the benzene ring and the hydrazinecarboxyl-ate plane is 13.82â (6)°. In the crystal structure, mol-ecules are linked into centrosymmetric dimers by N-Hâ¯O and C-Hâ¯O hydrogen bonds, and the dimers are linked together by C-Hâ¯π inter-actions.