The synthesis of diketone 14 possessing the tricyclo[9.3.1.03,8]pentadecane (ABC) taxane ring system is described. This concise approach employs a Wacker oxidation, intramolecular aldol condensation-dehydration, and a highly exo-stereoselective intermolecular Diels-Alder reaction as key steps.
Raman and IR spectra of neat n-pentadecane were measured as a function of increasing hydrostatic pressure up to 56 and 54 kbar, respectively. The application of high pressure leads to drastic changes in the frequencies, intensities and band shapes of the CH stretching and CH bending modes. The p...
Treatment of hexacyclo[7.4.2.01,9.03,7.04,14.06,15]pentadecane-10,12-diene-2,8-dione with aqueous sodium cyanide produced 2,8-dihydroxy-hexacyclo[7.4.2.01,9.03,7.04,14.06,15]pentadecane-10,12-diene-2,8-lactam and with sodium cyanide, ammonium chloride and ammonium hydroxide, 2-amino-8-hydroxy-he...
New enantiomerically pure macrocyclic aminals (2R,7R)- and (2S,7S)-1,8,10,12-tetraazatetracyclo[8.3.1.1.8,1202,7]pentadecane (4a and 4b) were obtained by a three component reaction between their respective pure enantiomer of trans-1,2-diaminocyclohexane, ammonia, and formaldehyde. Additionally, ...
Efficient syntheses of phenyl/N-heterocycle fused 6,13-dioxa-2-aza-tricyclo[8.3.1.02,8]tetradecanes have been accomplished from 8-hydroxy quinoline derivatives under solvent-free condition, using basic alumina as the solid support. The methodology was successfully extended for the synthesis of c...
Cyclohexanones react with phenylacetylene in a KOH/DMSO suspension (80 °C, 1 h) to give unexpectedly phenylmethylidene dispirocyclic ketals, 15-[(Z)-phenylmethylidene]-7,14-dioxadispiro[5.1.5.2]pentadecanes, in 16–22% yields (along with the anticipated β,γ- and α,β-ethylenic ketones).
Electrochemical behaviour of triactivated thiopyrans has been investigated in protic medium. Electroreduction of 4-dimethylamino-2,3,5-trimethoxycarbonyl-4H-thiopyran I first led to 2,3, 5-trimethoxy-carbonyl-2H-thiopyran IV, with elimination of dimethylamine; further reduction at more negative ...
The behaviour of endo selective diene 4 in kinetically controlled hetero Diels-Alder cycloadditions is in marked contrast with that of its exo selective aza analogue 1.
The cycloaddition of 2- or 2,3-substituted 1-thia- and 1-thia-3-aza-4-dimethylamino-buta-1,3-dienes with various dienophiles in the presence of a Lewis acid provides a rapid and diastereoselective access to the 3,4-dihydro-2H-thiopyran and 5,6-dihydro-4H-[1,3]thiazine backbones. The generally ob...
The NaH-promoted tandem Michael addition/intramolecular Horner–Wittig reaction of bis(diphenylphosphinoylmethyl)sulfide with chalcones afforded 3,4-dihydro-2H-thiopyrans 3a–l in 78–88% yield.
The assignment of the cis and trans configuration of 3,4-dimethyl-6-t-butyl-5,6-dihydro-2H-thiopyran-S-oxides and S-Methyl cations is made by 13C and 17O NMR, and by force field calculations. It is shown that the preferred conformation of all compounds is the half chair and that a previous confi...
Highly diastereoselective synthesis of cis-β-lactams via [2+2] cycloaddition reactions of imines derived from a chiral bicyclic aldehyde and ketenes is described. The chiral bicyclic aldehyde as well as chiral acids were prepared from commercially available inexpensive isosorbide. The cycloaddi...
Under mild conditions, 1,4:3,6-dianhydro-D-glucitol is converted by boron trichloride mainly into 1,6-dichloro-1,6-dideoxy-D-glucitol, isolated as the 2,4-O-benzylidene and 2,4:3,5-di-O-benzylidene derivatives. 2,4-O-Benzylidene-1,6-dichloro-1,6-dideoxy-D-glucitol is converted by sodium methoxid...
Using a highly selective lipase from Pseudomonas sp. (SAM II) the isomerically pure title compounds 3 and 4 were prepared either by enzymatic hydrolysis (alcoholysis) of the diacetate 2 or by enzymatic esterification of the diol 1, respectively. They were futher converted into the pharmaceutical...
A new series of esters was prepared by esterification of 1,4:3,6-dianhydro-d-glucitol with long chain fatty acid chlorides. The experimental conditions prevented thermal degradation of the sugar and led to diesters with a high degree of purity. The final products were readily isolated and charac...
1,4:3,6-dianhydro-D-glucitol 2-acetate (4) and its isomeric 5-actetate (2) derivatives has been prepared on multigram scale using immobilized Pseudomonas sp. lipase mediated acylation/deacylation reactions in organic solvents. The acylation of 1,4:3,6-dianhydro-D-glucitol (1) occurred in ethyl a...
BackgroundIntrahepatic cholestasis of pregnancy (ICP), as a pregnancy-specific liver disorder, obtains increasing recognition due to a series of adverse outcomes. ICP is generally characterized by pruritus and jaundice, and closely related to abnormalities in the metabolism and disposition of bi...
BackgroundDysregulation of systemic bile acid homeostasis can lead to cholestatic liver diseases and metabolic syndromes. As important anti-inflammatory and immunosuppressive drugs, synthetic glucocorticoids (GCs) are used to treat several cholestatic disorders, including biliary atresia (BA), b...
Clinicians sometimes encounter difficulty in choosing a therapeutic strategy due to the uncertainty regarding the type of liver injury. In particular, cholestasis is difficult to diagnose by conventional markers at an early stage of disease. The aim of this study was to identify promising biomar...
Bile acid homeostasis is maintained by liver synthesis, bile duct secretion, microbial metabolism and intestinal reabsorption into the blood. When drug insults result in liver damage, the variances of bile acids (BAs) are related to the physiological status of the liver. Here, we established a m...
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