RESUMO
In the title compound, C(16)H(14)Cl(2)O(3), the dihedral angle between the mean planes of the two benzene rings is 55.30â (5)°. The methyl ester group lies within the ring plane due to an intra-molecular O-Hâ¯O hydrogen bond [maximum deviation from the C(8)O(2) mean plane is 0.0383â (13)â Å]. In the crystal, mol-ecules are held together by rather weak C-Hâ¯O hydrogen bonds.
RESUMO
O,O'-3,3'-Di-tert-butyl-5,5'-dimethoxy-1,1'-biphenyl-2,2'-diyl phosphonate (1) is the hydrolysis product of several mono- and bis-phosphites used as ligands in industrial hydroformylation and other catalytic reactions. As a result of a tautomeric equilibrium, this pentavalent heteroatom-substituted phosphine oxide (HASPO) can rearrange to the corresponding trivalent phosphorus compound. The latter is able to react with typical rhodium-containing precursors frequently used for the generation of catalysts. The resulting species were characterised by NMR spectroscopy and X-ray structure analysis. Proof is given that a rhodium complex of 1 forms an active hydroformylation catalyst. Moreover, 1 can add to aldehydes, which are generated as products in the hydroformylation. Thus a broad range of subsequent reactions can be associated with the degradation of the original phosphite ligands, which has a strong influence on the overall outcome of the hydroformylation reaction.
RESUMO
The synthesis and structure of a dimeric aluminium hydroxide complex containing the novel chelating 1,4-disiloxide ligand [CH(2){Me(Me(3)Si)(2)Si}(2)SiO](2)(2-) (2)-2H is reported. [CH(2){Me(Me(3)Si)(2)Si}(2)SiO](2)AlOH (4) was prepared by careful hydrolysis of [CH(2){Me(Me(3)Si)(2)Si}(2)SiO](2)AlMe·THF (3).
RESUMO
1-Hydroxy-3,5-dimethyl-2,4-benzodioates (4-hydroxyisophthalates) were prepared by [3+3] cyclocondensation of 1,3-bis(silyloxy)-1,3-butadienes with 3-ethoxycarbonyl-4-trimethylsilyloxy-3-penten-2-one which is synthesized from (symmetrical) ethyl 2-acetylacetoacetate. The [3+3] cyclization of 1,3-bis(silyloxy)-1,3-butadienes with 3-alkoxy-2-alkoxycarbonyl-2-en-1-ones, readily available by reaction of beta-ketoesters with trialkyl orthoformiates, provide a convenient and regioselective approach to a great variety of 3-substituted 1-hydroxy-2,4-benzodioates that are not readily available by other methods.
Assuntos
Álcoois/química , Butadienos/química , Catálise , Compostos Bicíclicos com Pontes/química , Ciclização , Hidrogenação , Silanos/química , EstereoisomerismoRESUMO
The formal [3+3] cyclization of 1,3-bis(silyloxy)-1,3-butadienes with readily available 2-arylsulfonyl-3-ethoxy-2-en-1-ones resulted in regioselective formation of 4-(arylsulfonyl)phenols.
RESUMO
N-glycosides of 6H-indolo[2,3-b]quinoxalines were prepared and structurally characterized. The synthesis relies on the cyclocondensation of isatine-N-glycosides with 1,2-diaminobenzenes. Some products exhibit weak cytotoxic activity against human ceratinocytes (HaCaT).
Assuntos
Glicosídeos/síntese química , Glicosídeos/toxicidade , Indóis/química , Queratinócitos/efeitos dos fármacos , Quinoxalinas/química , Glicosídeos/química , HumanosRESUMO
A variety of functionalized 3,4-benzo-7-hydroxy-2,9-diazabicyclo[3.3.1]non-7-enes were prepared by one-pot cyclizations of 1,3-bis(silyl enol ethers) with quinazolines. The mechanism of the cyclization was studied by B3LYP/6-31G(d) density functional theory computations. The products could be functionalized by Suzuki cross-coupling reactions. The reaction of 1,3-bis(silyl enol ethers) with phthalazine afforded open-chain rather than cyclization products.
RESUMO
Densely functionalized azoxabicyclo[3.3.1]nonanones were prepared by regio- and diastereoselective condensation of 1,1-bis(silyloxy)ketene acetals with isoquinolinium and quinolinium salts and subsequent regioselective and stereospecific iodolactonization.
Assuntos
Acetais/química , Compostos Azabicíclicos/síntese química , Isoquinolinas/química , Quinolinas/química , Compostos de Trimetilsilil/química , Compostos Azabicíclicos/química , Ciclização , Etilenos/química , Formiatos/química , Cetonas/química , Estrutura Molecular , EstereoisomerismoRESUMO
The first indirubin-N'-glycosides were prepared based on reactions of isatin-N'-glycosides with indoxyls. The products show a significant anti-proliferative activity against various human cancer cell lines. Good results were observed for an indirubin-N'-mannoside which was shown to have medium to high anti-proliferative activity against all investigated cell lines. The highest activities and selectivities against the MCF-7 breast cancer cell line were observed for indirubin-N'-rhamnosides.
Assuntos
Antineoplásicos/síntese química , Antineoplásicos/farmacologia , Glicosídeos/síntese química , Glicosídeos/farmacologia , Antineoplásicos/química , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Cristalografia por Raios X , Relação Dose-Resposta a Droga , Ensaios de Seleção de Medicamentos Antitumorais , Glicosídeos/química , Humanos , Indóis/química , Modelos Moleculares , Conformação Molecular , Estereoisomerismo , Relação Estrutura-AtividadeRESUMO
To understand the contradictory results on the structure of the lipopolysaccharide isolated from a Yersinia enterocolitica O:3, both anomers of methyl 2-acetamido-2,6-dideoxy-d-xylo-hexopyranosid-4-ulose were prepared. The key steps of the synthetic pathway were the selective acetylation of the methyl 2-acetamido-2,6-dideoxy-alpha,beta-d-glucopyranosides, the oxidation of the 4-position to form the keto-sugars, and deacetylation to provide the target compound. Surprisingly, the last step was accompanied by a disproportionation to give methyl 2-acetamido-2,6-dideoxy-alpha- and beta-d-glucopyranosides and N-(5-hydroxy-6-methyl-4-oxo-4H-pyran-3-yl)acetamide as side-products.
Assuntos
Cetoácidos/síntese química , Cetoses/síntese química , Acetilação , Cetoácidos/química , Cetoses/química , Espectroscopia de Ressonância Magnética , Estrutura MolecularRESUMO
Functionalized dibenzo[b,d]pyran-6-ones were prepared by formal [3 + 3] cyclization of 1,3-bis(silyl enol ethers) with 3-silyloxy-2-en-1-ones or 1,1-diacetylcyclopropane to give functionalized salicylates, Suzuki cross-coupling reactions of the corresponding triflates, and subsequent BBr3-mediated lactonization. A second approach to dibenzo[b,d]pyran-6-ones relies on the [3 + 3] cyclization of 1,3-bis(silyl enol ethers) with 1-(2-methoxyphenyl)-1-(trimethylsilyloxy)alk-1-en-3-ones and subsequent BBr3-mediated lactonization.
Assuntos
Química Orgânica/métodos , Piranos/química , Silanos/química , Benzoatos/química , Éteres/química , Modelos Químicos , Conformação Molecular , Oxigênio/química , Piranos/síntese química , Salicilatos/químicaRESUMO
Starting from 1,2,4-tri-O-acetyl-3,6-anhydro-alpha-d-galactopyranose, 4-O-acetyl-3,6-anhydro-1,2-O-(1-cyanoethylidene)-alpha-d-galactopyranose (7) was synthesized by treatment with cyanotrimethylsilane. Additionally, 3,4-di-O-acetyl-1,2-O-(1-cyanoethylidene)-6-O-tosyl-alpha-d-galactopyranose was prepared from the corresponding bromide and both cyanoethylidene derivatives were used as donors in glycosylation reactions. The coupling with benzyl 2,4,6-tri-O-acetyl-3-O-trityl-beta-d-galactopyranoside provided exclusively the beta-linked disaccharides in approximately 30% yield. The more reactive methyl 2,3-O-isopropylidene-4-O-trityl-alpha-l-rhamnopyranoside gave with donors 3 and 7 the corresponding disaccharides in nearly 60% yield. Furthermore, the synthesis of 3,6-anhydro-4-O-trityl-1,2-O-[1-(endo-cyano)ethylidene]-alpha-d-galactopyranose, which can be used as a monomer for polycondensation reaction is described.
Assuntos
Cianetos/síntese química , Galactose/análogos & derivados , Dissacarídeos/síntese química , Galactose/química , GlicosilaçãoRESUMO
The dithionite-mediated addition of BrCF(2)Cl to 3,4-di-O-pivaloyl-D-xylal (1) generated preferably 1-CF(2)Cl-substituted products, that is, (2-bromo-2-deoxy-3,4-di-O-pivaloyl-beta-D-xylopyranosyl)-chlorodifluoromethane and (2-deoxy-3,4-di-O-pivaloyl-beta-D-threo-pentopyranosyl)-chlorodifluoromethane. Selected chlorodifluoromethyl-substituted monosaccharide derivatives were hydrodechlorinated or alkylated at the CF(2)Cl-group using tin reagents under radical reaction conditions. Thus, hydrodechlorinations of (2,3,4-tri-O-acetyl-6-deoxy-alpha-L-galactopyranosyl)-chlorodifluoromethane and of methyl 3,4-di-O-acetyl-2-C-chlorodifluoromethyl-2,6-dideoxy-alpha/beta-L-glucopyranoside are reported using tri-n-butyltin hydride initiated by AIBN. UV-initiated allylations are reported for reactions of (2-deoxy-3,4-di-O-pivaloyl-beta-D-threo-pentopyranosyl)-chlorodifluoromethane, (2,3,4-tri-O-acetyl-6-deoxy-alpha-L-galactopyranosyl)-chlorodifluoromethane, 1,3,4,6-tetra-O-acetyl-2-C-chlorodifluoromethyl-2-deoxy-alpha-D-glucopyranose, 1,3,4,6-tetra-O-acetyl-2-C-chlorodifluoromethyl-2-deoxy-alpha-D-mannopyranose and methyl 3,4-di-O-acetyl-2-C-chlorodifluoromethyl-2-deoxy-alpha/beta-D-rabinopyranoside with allyltri-n-butyltin.
Assuntos
Carbono/química , Cloro/química , Clorofluorcarbonetos de Metano/química , Monossacarídeos/química , Modelos Moleculares , Compostos de Trialquitina/químicaRESUMO
The attempted conversion, by treatment with CsF/TBFA in MeCN, of acetylated derivatives of 2-chlorodifluoromethyl-2-deoxyhexopyranoses into their corresponding 2-trifluoromethyl derivatives was always accompanied by an elimination reaction. Thus, representative educts with the D-gluco- and D-manno-configuration gave derivatives of 2,3-dideoxy-2-trifluoromethyl-D-erythro-hex-2-enopyranose and 1,5-anhydro-2-deoxy-2-trifluoromethyl-d-arabino-hex-1-enitol, respectively. X-ray analyses are given for 1,3,4,6-tetra-O-acetyl-2-chlorodifluoromethyl-2-deoxy-alpha-D-mannopyranose and 4,6-di-O-acetyl-2,3-dideoxy-2-trifluoromethyl-alpha-D-erythro-hex-2-enopyranose.
Assuntos
Carboidratos/química , Cianetos/química , Desoxiaçúcares/química , Fluorenos/química , Glicosídeos/síntese química , Metano/análogos & derivados , Piranos/química , Configuração de Carboidratos , Cromatografia , Cromatografia em Camada Fina , Hidrocarbonetos , Hidrogênio , Espectroscopia de Ressonância Magnética , Metano/química , Modelos Químicos , Modelos Moleculares , Raios XRESUMO
In a one step procedure, L-1-O-benzyl-2-O-methyl-chiro-inositol (1) was acetalized to the L-muco-inositol derivatives 2, 3 and D-2-O-benzyl-3-O-cyclohexylcarbamoyl-4-deoxy-4-(N,N'-dicyclohexylureido)-1-O-methyl-5,6-O-trichloroethylidene-chiro-inositol (4). Complete conversion of L-1-O-benzyl-6-O-cyclohexylcarbamoyl-3-O-formyl-2-O-methyl-4,5-O-trichloroethylidene-muco-inositol (3) into L-1-O-benzyl-6-O-cyclohexylcarbamoyl-2-O-methyl-4,5-O-trichloroethylidene-muco-inositol (2) is feasible by deformylation in boiling methanolic triethylamine. Furthermore, stepwise deprotection of 2 and 4 is described. Thus, compounds 5, 10, and 7 were obtained by decarbamoylation of 2, 4, and 6, respectively, with boiling methanolic sodium methoxide. The trichloroethylidene group of L-1-O-benzyl-2-O-methyl-4,5-O-trichloroethylidene-muco-inositol (5) was removed in a two step procedure (hydrodechlorination-deacetalization) via the ethylidene acetal 7 to give L-1-O-benzyl-2-O-methyl-muco-inositol (9). On refluxing D-chiro-inositol derivative 4 with 99% acetic acid, the ureido moiety was cleaved generating D-2-O-benzyl-4-cyclohexylamino-3-O-cyclohexylcarbamoyl-4-deoxy-1-O-methyl-5,6-O-trichloroethylidene-chiro-inositol (11). By contrast, cleavage of the ureido moiety of 10 was relatively difficult. The corresponding D-2-O-benzyl-4-cyclohexylamino-4-deoxy-1-O-methyl-5,6-O-trichloroethylidene-chiro-inositol (12) was only formed in small amounts. The structures of 1, 3 and 10 were confirmed by X-ray analysis.