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Molecules, Volume 10, Issue 7 (July 2005) – 11 articles , Pages 747-832

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Article
Synthesis of 1,3,4-Thiadiazole, 1,3,4-Thiadiazine, 1,3,6-Thiadiazepane and Quinoxaline Derivatives from Symmetrical Dithiobiureas and Thioureidoethylthiourea Derivatives
Molecules 2005, 10(7), 822-832; https://doi.org/10.3390/10070822 - 31 Aug 2005
Cited by 17 | Viewed by 8022
Abstract
Reactions of N,N`-disubstituted hydrazinecarbothioamides 8a-c and substituted thioureidoethylthioureas 9a-c with 2,3,5,6-tetrachloro-1,4-benzoquinone (chloranil, 10a) and 2,3,5,6-tetrabromo-1,4-benzoquinone (bromanil, 10b) to form N,N`-disubstituted [1,3,4]thiadiazole-2,5-diamines 11a-c, 6,7-dichloro-3-substituted amino-1H-benzo[1,3,4]- thiadiazine-5,8-diones 12a-c, 2,3,7,8-tetrahalothianthrene-1,4,6,9-tetraones 13a,b, 5,6,8- trihalo-7-oxo-3,7-dihydro-2H-quinoxaline-1-carbothioic acid substituted amides 14a-c, 15a-c and 7-substituted imino-[1,3,6]thiadiazepane-3-thiones 16a-c are reported. Rationales for [...] Read more.
Reactions of N,N`-disubstituted hydrazinecarbothioamides 8a-c and substituted thioureidoethylthioureas 9a-c with 2,3,5,6-tetrachloro-1,4-benzoquinone (chloranil, 10a) and 2,3,5,6-tetrabromo-1,4-benzoquinone (bromanil, 10b) to form N,N`-disubstituted [1,3,4]thiadiazole-2,5-diamines 11a-c, 6,7-dichloro-3-substituted amino-1H-benzo[1,3,4]- thiadiazine-5,8-diones 12a-c, 2,3,7,8-tetrahalothianthrene-1,4,6,9-tetraones 13a,b, 5,6,8- trihalo-7-oxo-3,7-dihydro-2H-quinoxaline-1-carbothioic acid substituted amides 14a-c, 15a-c and 7-substituted imino-[1,3,6]thiadiazepane-3-thiones 16a-c are reported. Rationales for the observed conversions are presented. Full article
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Article
3-Formylchromones IV. The Rearrangement of 3-Formylchromone Enamines as a Simple, Facile Route to Novel Pyrazolo[3,4-b]pyridines and the Synthetic Utility of the Latter
Molecules 2005, 10(7), 809-821; https://doi.org/10.3390/10070809 - 31 Aug 2005
Cited by 16 | Viewed by 6672
Abstract
One-pot and facile preparations of 6-(2-hydroxy-5-R-benzoyl)-4-methyl-2-R1- pyrazolo[3,4-b]pyridines 4a-o are described, using the reaction of 3-formyl chromones 1 with 5-amino-1-R1-pyrazoles 2. An enamine-intermediate 2-ethyloxy-6-R-3-(3-methyl-1- phenylpyrazol-5-ylaminomethylene)chroman-4-one 3 was isolated at lower temperatures. Acyloxy-derivatives 5 of compounds 4 were obtained by acylation with acid chlorides or [...] Read more.
One-pot and facile preparations of 6-(2-hydroxy-5-R-benzoyl)-4-methyl-2-R1- pyrazolo[3,4-b]pyridines 4a-o are described, using the reaction of 3-formyl chromones 1 with 5-amino-1-R1-pyrazoles 2. An enamine-intermediate 2-ethyloxy-6-R-3-(3-methyl-1- phenylpyrazol-5-ylaminomethylene)chroman-4-one 3 was isolated at lower temperatures. Acyloxy-derivatives 5 of compounds 4 were obtained by acylation with acid chlorides or acid anhydrides. Coumarins 6 substituted at the 3- and 4-positions were prepared from the pyrazolo[3,4-b]pyridines 4 by condensation reactions and hydrazones 7 were formed from their reaction with 2,4-dinitrophenyl hydrazine. Reactions under microwave irradiation proceeded significantly faster and with high yields. Full article
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Article
Synthesis of Steroidal Thiadiazoles from Steroidal Ketones
Molecules 2005, 10(7), 803-808; https://doi.org/10.3390/10070803 - 31 Aug 2005
Cited by 5 | Viewed by 6040
Abstract
Syntheses of steroidal heterocycles containing a five-membered N,S- heterocycle attached at the 6,7 positions of the B ring are reported. 5α-Cholestane-6-one (1), its 3β-acetoxy- (2) and 3β-chloro- (3) analogues reacted with semicarbazide and aqueous sodium acetate in refluxing ethanol to yield 5α-cholestan-6-one-semicarbazone 1a [...] Read more.
Syntheses of steroidal heterocycles containing a five-membered N,S- heterocycle attached at the 6,7 positions of the B ring are reported. 5α-Cholestane-6-one (1), its 3β-acetoxy- (2) and 3β-chloro- (3) analogues reacted with semicarbazide and aqueous sodium acetate in refluxing ethanol to yield 5α-cholestan-6-one-semicarbazone 1a and its 3-β-acetoxy and 3β-chloro derivatives 2a and 3a, respectively. The reactions of 1a, 2a and 3a with thionyl chloride in dichloromethane at low temperature afforded the cyclized thiadiazole 4 and its 3β-acetoxy- and 3β-chloro analogues 5 and 6 in good yields. Full article
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Article
Chemical Constituents of Piper betle Linn. (Piperaceae) Roots
Molecules 2005, 10(7), 798-802; https://doi.org/10.3390/10070798 - 31 Aug 2005
Cited by 29 | Viewed by 9345
Abstract
Column chromatography of the alcoholic extract of Piper betle roots furnished aristololactam A-II and a new phenyl propene, characterized as 4-allyl resorcinol, while the petroleum-ether extract yielded a diketosteroid, viz. stigmast-4-en-3,6-dione. All these compounds were characterized by spectroscopic means. Isolation of these compounds [...] Read more.
Column chromatography of the alcoholic extract of Piper betle roots furnished aristololactam A-II and a new phenyl propene, characterized as 4-allyl resorcinol, while the petroleum-ether extract yielded a diketosteroid, viz. stigmast-4-en-3,6-dione. All these compounds were characterized by spectroscopic means. Isolation of these compounds from this source is being reported here for the first time. Full article
Article
An Efficient and Selective Solvent-free Oxidation of Alcohols by Shaking with Chromium Trioxide Supported on Aluminium Silicate
Molecules 2005, 10(7), 794-797; https://doi.org/10.3390/10070794 - 31 Aug 2005
Cited by 7 | Viewed by 6529
Abstract
A selective oxidation of primary alcohols to the corresponding aldehydes by shaking with chromium trioxide supported on aluminium silicate at room temperature under solvent free conditions is reported. This new procedure can also oxidise secondary alcohols. Full article
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Article
Highly Lipophilic Benzoxazoles with Potential Antibacterial Activity
Molecules 2005, 10(7), 783-793; https://doi.org/10.3390/10070783 - 31 Aug 2005
Cited by 52 | Viewed by 7205
Abstract
A series of lipophilic 2-substituted 5,7-di-tert-butylbenzoxazoles was prepared in average yields by the reaction of 3,5-di-tert-butyl-1,2-benzoquinone with amino acids and dipeptides bearing N-terminal glycine. Dipeptides having other N-terminal amino acids undergo oxidative deamination. 5,7-Di-tert-butylbenzoxazoles have shown activity against Mycobacterium tuberculosis and some nontuberculous [...] Read more.
A series of lipophilic 2-substituted 5,7-di-tert-butylbenzoxazoles was prepared in average yields by the reaction of 3,5-di-tert-butyl-1,2-benzoquinone with amino acids and dipeptides bearing N-terminal glycine. Dipeptides having other N-terminal amino acids undergo oxidative deamination. 5,7-Di-tert-butylbenzoxazoles have shown activity against Mycobacterium tuberculosis and some nontuberculous strains where isoniazid has been inactive. Antifungal activity was mediocre. Full article
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Article
Regioselective Synthesis of Vinylic Derivatives of Common Monosccarides Through Their Activated Stannylene Acetal Intermediates
Molecules 2005, 10(7), 772-782; https://doi.org/10.3390/10070772 - 31 Aug 2005
Cited by 9 | Viewed by 6009
Abstract
The regioselective C-2-O-acrylation and metacrylation of methyl 4,6-O-benzylidene-α-D-glucopyranoside and methyl 4,6-O-benzylidene-α-D-galactopyranosidethrough their corresponding organotin intermediates have been studied. Regioselectivitywas achived through the formation of a tin chelate of the 2,3-diols. Thus, methyl 4,6-O-benzylidene-α-D-glucopyranoside and methyl 4,6-O-benzylidene-α-D-galactopyranosidewere reacted with dibutylstannylene to give the corresponding [...] Read more.
The regioselective C-2-O-acrylation and metacrylation of methyl 4,6-O-benzylidene-α-D-glucopyranoside and methyl 4,6-O-benzylidene-α-D-galactopyranosidethrough their corresponding organotin intermediates have been studied. Regioselectivitywas achived through the formation of a tin chelate of the 2,3-diols. Thus, methyl 4,6-O-benzylidene-α-D-glucopyranoside and methyl 4,6-O-benzylidene-α-D-galactopyranosidewere reacted with dibutylstannylene to give the corresponding dibutylstannylene acetalintermediates that were then reacted in a regioselective manner with acryloyl chloride ormetacryloyl chloride in the presence of triethylamine (TEA) or pyridine to give thevinylic type monomeric compounds. The monomeric products containing glucose andgalactose units from each reaction were separated by column chromatography using agradient of n-hexane and ethyl acetate as eluant. The structure of the obtained compoundswere confirmed using 1H-, 13C- and 2D NMR spectroscopy. Full article
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Article
Structural Investigation of bis(4-Methyl-1-piperazineglyoximato)dipyridinato Cobalt(III) Chloro Dinitrate Trihydrate
Molecules 2005, 10(7), 767-771; https://doi.org/10.3390/10070767 - 31 Aug 2005
Cited by 2 | Viewed by 5804
Abstract
The crystal and molecular structure of the title compound,C24H36CoN10O4·2(NO3)·3(H2O)·Cl, have been determined by X-ray analysis: Cc (No: 9),a = 17.6920(4) å, b = 11.8163(2) å, c = 16.4752(4) å, ß = [...] Read more.
The crystal and molecular structure of the title compound,C24H36CoN10O4·2(NO3)·3(H2O)·Cl, have been determined by X-ray analysis: Cc (No: 9),a = 17.6920(4) å, b = 11.8163(2) å, c = 16.4752(4) å, ß = 91.679(1)°, Z = 4. The Co(III)ion is six-coordinated with octahedral geometry, the pyridine rings are planar and thepiperazine rings assume chair conformations. Full article
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Article
Pechmann Reaction Promoted by Boron Trifluoride Dihydrate
Molecules 2005, 10(7), 762-766; https://doi.org/10.3390/10070762 - 31 Aug 2005
Cited by 19 | Viewed by 5867
Abstract
The Pechmann reaction of substituted phenols 1a-e with methyl acetoacetate (2) can be activated by boron trifluoride dihydrate (3) to give the corresponding 4-methyl- coumarin derivatives 4a-e in excellent yield (98-99 %). Full article
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Article
Three-Component Synthesis of Polysubstituted Homoproline Analogs
Molecules 2005, 10(7), 755-761; https://doi.org/10.3390/10070755 - 31 Aug 2005
Cited by 5 | Viewed by 4375
Abstract
Tetrasubstituted pyrrolidines representing analogs of homoproline weresynthesized by three-component condensation of aryl(heteroaryl)aldehydes, asparagineand N-methylmaleimide (NMM). Compounds with (1S*, 3R*, 3aS*, 6aR*)-configurationat the corresponding carbon positions of the bicyclic pyrrolidine ring could be isolated ona preparative scale. Full article
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Article
Studies on the Synthesis and Reactivity of Novel Benzofuran-2-yl-[3-Methyl-3-Phenylcyclobutyl] Methanones and their Antimicrobial Activity
Molecules 2005, 10(7), 747-754; https://doi.org/10.3390/10070747 - 31 Aug 2005
Cited by 12 | Viewed by 5583
Abstract
Preparation in excellent yields of cyclobutyl benzofuran-2-yl- and naphthofuran- 2-yl-ketones, the corresponding ketoximes and thiosemicarbazones, ether derivatives of the ketoximes and thiazoles derived from the thiosemicarbazones are described. Two of the synthesized compounds have been tested against eight different microorganisms and found to [...] Read more.
Preparation in excellent yields of cyclobutyl benzofuran-2-yl- and naphthofuran- 2-yl-ketones, the corresponding ketoximes and thiosemicarbazones, ether derivatives of the ketoximes and thiazoles derived from the thiosemicarbazones are described. Two of the synthesized compounds have been tested against eight different microorganisms and found to be active against some of the species studied. Full article
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