Synthesis of Trisaccharide of Incanosides from Caryopteris incana

Recent evidence has accumulated suggesting that free radicals are involved in many deterioration processes. They attack the unsaturated fatty acids in the biomembranes resulting in membrane lipid peroxidation, which is strongly connected with aging, carcinogenesis and atherosclerosis.[1] Free radicals also attack DNA and cause mutation leading to cancer.[2] Thus it is desirable to look for effective radical scavengers. In 1999, Gao et al.[3] isolated incanosides C, D and E from the whole plant of Caryopteris incana (THUNB.). These natural products were proved to exhibit good radical scavenging activities against DPPH radical and inhibitory activities against the oxidation of linoleic acid.[4] Herein, for the first time we report the synthesis of trisaccharide phenyl 2,3,4,6-tetra-O-acetyl-β-D-glucopyranosyl-(1→2)-3,4-di-O-benzoyl-α-L-rhamno-pyranosyl-(1→3)-2-O-acetyl-4,6-O-benzylidene-1-thio-β-D-glucopyranoside (1), which is the common carbohydrate moiety of incanosides C, D and E.     

Synthesis of the Precursor of Tetrasaccharide from Laminin

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Synthesis of Enantionpure tert-Butylsulfinamide from tert-Butylsulfinyloxazolidinone

As a versatile chiral ammonia equivalent, chiral tert-butylsulfinylamide (6) (TBSA) is a very useful auxiliary due to the characteristics of highly stereoselectivity in asymmetric induction and the sulfinyl group being easily removed compared with other amine auxiliaries since its introduction as a stable compound by Ellman in 1997.[1] Considering the importance of TBSA 6, search for efficient methods for the preparation of enantiopure TBSA (6) is the great interesting topic in synthetic chemistry. There were only three methods for the preparation of enantiopure TBSA (6) reported in the literature.[2] In this paper, we report an alternative three-step procedure to synthesize enantiopure TBSA (6) with a key step being the formation of tert-butylsulfinyloxazolidinone (4).     

Azetidine iminosugars from the cyclization of 3,5-di-O-triflates of α-furanosides and of 2,4-di-O-triflates of β-pyranosides derived from glucose

Primary amines with either 3,5-di-O-ditriflates of α-furanosides or 2,4-di-O-triflates of β-pyranosides form bicyclic azetidines in high yield.     

Alkaloids from stems of Ervatamia yunnanensis

Six indole alkaloids were isolated from the stems of Ervatamia yunnanensis. Among them, yunnanensine (I) is new. The other five are known alkaloids, namely: 19,20-E-vallesamine (II), 19s-heyneanine (HI), ibogaine (IV), ibogamine (V), coronaridine (VI). The structural elucidation of the alkaloids was based on spectral means.     

Preparation of dehydromorpholines from β-cyanoethyl ethers of acetylenic alcohols

Summary A method has been developed for the synthesis of dehydromorpholines from-cyanoethyl ethers of acetylenic alcohols.     

Antioxidant Activity of Ecdysteroids from Serratula strangulata

One new ecdysteroid,(24R)-24-(2-hydroxyethyl)-20-hydrox-yecdysone(3),as well three known ecdysteroids,has been isolated from Chinese herb serratula strangulata and these compoundsd 1-4 showed effective antioxidant activity on AAPH-induced hemolysis of human RBC and Fe^2 cysteine-induced lipid peroxidation of liver microsome.     

Quantification of acetone emission from pine plants

Acetone emission from pine plants (pinus sylvestris) is measured by continuously stirred tank reactor. Under a constant light intensity, acetone emission rates increase exponentially with leaf temperature. When leaf temperature is kept constant, acetone emission increases with light intensity. And acetone emission in darkness is also detected. Acetone emitted from pine is quickly labeled by 13C when the plants are exposed to air with 630 mg/m313CO2. However, no more than 20% of acetone is 13C labeled. Acetone emission from pine may be due to both leaf temperature-controlled process and light intensity-controlled process. Based on these understandings, an algorithm is used to describe the short term acetone emission rates from pine.     

Copper-catalyzed synthesis of α-ketothioamides from ketones

In this paper, the conversion of acetophenone to α-ketothioamide was reported in the presence of CuI as the catalyst and S₈/DMF as the coupling partners. The presence of both KF and NaOH was found to be necessary to achieve the high yield of the product. Propiophenone and butyrophenone also reacted in the presence of phenylboronic acid as an additive. Willgerodt-Kindler products were not observed in these reactions.     

Synthesis of Isoquinoline Derivatives from β-Hydroxyarylethanamides

A simple and efficient protocol for the construction of medicinally important substituted isoquinolines through intramolecular cyclization of β-hydroxyarylethanamides using acetic anhydride and phosphorous pentoxide in dioxane has been described. The chemo- and regioselectivities due to the influence of different catalysts were investigated and optimized for good to excellent yields. All the synthesized compounds have been characterized by NMR and mass spectral analyses.     

Polyoxypregnanes from the stems of Marsdenia tenacissima

From the stems ofMarsdenia tenacissima two new polyoxypregnanes were isolated, their structures were elucidated by 1D, 2D-NMR as 11α,12β-di-O-tigloyl-tenacigenin B （1） and tenacigenoside E （2）.     

Synthesis of 6β-Halogenodeoxyneopine from Neopine

(-)-Neopine (1), the Δ^8,14 isomer of codeine, occurs as one of the minor constituents in opium from Papaver somniferum L¹. In opium alkaloids of the morphine group the hydroxyl group in position 6 is readily converted with p-toluenesulfonyl chloride or methanesulfonyl chloride into the respective 6α-O-sulfonyl derivatives². The latter in turn form starting materials for the preparation of other derivatives. Thus, with lithium halides, via a S_N2 mechanism³ the 6β-halogen compounds are formed. It is found that, as a result of the allylic system, under slightly changed reaction conditions codeine itself can also yield the 8β-chloro derivative⁴.     

Syntheses of a new type of chiral phosphines from glucose

Methyl 3-deoxy-3-(diphenylphosphino)-4,6-O-benzylidene-α-D-altropyranoside (1) and methyl 2-deoxy-2-(diphenylphosphino)-4,6-O-benzylidene-α-D-altropyranoside (2) were prepared from methyl 2,3-anhydro-4,6-O-benzylidene-O-D-mannopyranoside and methyl 2,3-anhydro-4,6-O-benzyl-idene-α-D-allopyranoside,respectively,via regioselective and stcreospecific ring-opening reactions in high yields.Compounds 1 and 2 were oxidized to give the corresponding phosphine oxides (3 and 4).     

Xanthones from the bark of Garcinia Xanthochymus

Two novel xanthones, 1,6-dihydroxy-4,5-dimethoxyxanthone (1) and 1,5,6-trihydroxy-7,8-di(3-methyl-2-butenyl)-60,60- dimethylpyrano(20,30:3,4)xanthone (2) were isolated from the bark of Garcinia xanthochymus by normal phase and reverse phase silica gel column chromatography. Their structures were elucidated by spectroscopic methods, especially 2D-NMR techniques.     

Alkaloids from the Roots of Saccopetalum prolificum

In recent years, an increased interest in the phytochemistry of the Annonaceae has beensparked by the isolation of the antileukemic Annonaceous acetogenin'. Saccopela/umprolificllm (Chun el How) Tsiang (Allnonaceae) is an evergreen tree distributed inHainan Province, P. R. China. The ethanolic extract of the plant exhibited cell growthinhibitory activity (20 ig/ml) against LIZ10 lymphocytic leukemia. A new alkaloid,prolifine (l), was isolated from the roots of S. proldicum, in addition t…     

Synthesis of Antipyrine Derivatives Derived from Dimedone

Coupling of dimedone with the diazonium salt of 4-aminoantipyrine afforded 2,3-dimethyl-4-[2-（5,5-dimethyl- 2,6-dioxocyclohex-2-ylidend）-hydrazino]-5-oxo-1-phenylpyrazoline （3）. Reaction of 3 with excess phenylhydrazine gave the mixed trishydrazone derivative 4. Treatment of 3 with hydroxylamine produced the bisoxime 5 which upon dehydrative cyclization with acetic anhydride gave the corrsponding tetrahydrobenzo[d][1,2,3]triazole derivative 7. A one-pot synthesis of 7 was done by reacting 3 with hydroxylamine hydrochloride in pyridine, followed by heatment with acetic anhydride.     

Determination of enthalpy of ionization of water from 250 to 350° C

The enthalpy changes at zero ionic strength (H°) for the ionization of water (H₂O=H⁺+OH^–) were determined by flow calorimetry from the heats of mixing of aqueous NaOH and HCl solutions in the temperature range 250 to 350°C. Pitzer ion-interaction models developed by other workers were used to calculate enthalpies of dilution of aqueous NaOH, HCl, and NaCl solutions for the extrapolation of H values from the conditions of the experiment to infinite dilution. Equations are derived for thermodynamic quantities (log K, H°, S°, C _p ^° and V°) for the ionization of water using the H° values determined in this study from 250 to 350°C and literature log K and H° values from 0 to 225°C. Smoothed values of log K, H°, S°, C _p ^° , and V° are presented at rounded temperatures from 0 to 350°C and at the saturation pressure of water for each temperature. The equations in the present study provide a better representation of experimental thermodynamic data from 0 to 350°C than the Marshall-Franck equation.     

Synthesis of 2-En-l-one-ebelactonyl Benzoates of Territrem B Analogues from Jujubogenin

Two series of territrem B analogues (10a-10c and 18) have been designed and synthesized from jujubogenin 5a which was prepared from jujubogenin glycosides 5b obtained from the leaves of Zizyphusjujuba. The structures of the new compounds were confirmed by 1H-,13C-NMR and MS data. Compounds 10c and 18 showed weak inhibitory effect on AChE at 10^-4 mol/E.     

Structural Features of Fructans from the Root of Cyathula officinalis Kuan

Three fructans (CoPS1, CoPS2 and CoPS3) were isolated from the root of Cyathula officinalis Kuan, a traditional Chinese medicine. The structures of the fructans were determined by methylation, reductive-deavage method combined with GC-MS analysis, and 13C NMR spectroscopy. These results show that the fructans (CoPS1, CoPS2 and CoPS3) are graminan type fructans, and comprised of (2→t)- and (2→6)-linked β-D-fructofuranosyl backbone residues containing high branches.     

One-Pot Synthesis of Substituted Cyclohexanes from Condensation of Aldehyde and Methylketone

Six-carbonringsareusuallypreparedfromDiels-Alder[2rr 4tt]cyclicaddition,DieckmanncondensationorintramolecularMichaelcondensati0n.H0wever,inmostofthecases,thepreparati0nofsubstitUtedcyclohexaneshastounderg0areacti0nsequence.Toreachthisbyaone-stepreaction,sofar,isstillapr0bleminsyntheticorganicchehastry.ThisletterintendstogiveapreliminaryrePortonanewmethodtosynthesizesubstitUtedcyclohexanesthroughsingle-stepintermolecularcondensation0fanaldehydeandamethylketoneinthepresenceofanalkali.Thereact…