Total Synthesis of the Analogue of Icogenin

It was well known that furostan saponin was a kind of natural products with a broadrange of promising pharmaceutical properities1. Structurally, furostan saponins usuallyhave bidesmosidic sugar moieties substituted at 3-OH and 26-OH position2. However,fur…     

Studies on the Synthesis of Preverecynarmin

Prev~n1,acembranopditerpenoid,wasfirstisolatedfromsoftcoral(VeretilIumcoporium)inl99(),anditSmCtUrwasehablishedas(+)-(lE,3E,7E,llE)-cembra-l,3,7,ll-tetraen6-olaeetate[l].SofarasweknOW,thetotalSynthsisof1hasnobeenrePOrtedyet.Herein.wewishtodescribethetotalpeisoftheprecursor(9),theSynthhcroutewasouthnedbelowfa)HBr.80%;b).CH3C02Na.CH3CO2H,75%,c).Se02-I-Bu00H,70%,d).CCl',PPh3,83%,e).NaSQPh.DMF.9O%,O.K=CO3.MeOH,95%,g).DHP,Ts0H.8O%,h),TBAB,5O%NaOH,aq.,5%;i).Li-Effez.M,70%;j…     

Synthesis of the diastereoisomeric Yingzhaosu D

Yingzhaosu D (1), coexisting with Yingzhaosu A (2) which is an antimalarial principlein a traditional Chinese herbal medicine Yingzhao (Artabotrys uncinatus L. Merr.), has shownto be a new polyhydroxy sesquiterpene. We have previously reported the synthesis of Ying-zhaosu A (2) and shown that the configuration at C-4 is S. It is therefore reasonable to as-sume that the corresponding carbon atom in Yingzhaosu D has the same absolute configura-tion. Herein we report an effective method to prepare Yingzhaosu D and its three stereo-     

Studies on the Synthesis of Villosol

TheindoidsxillosoIandt4llosolsidewereisolatalinl985frOmPatriDiavi11osa,atradihonalChineseherbmedicineusedfortreatofconunoncoldandparohhsmUInPS.PhannacologicalstUdieshaveestablishedthattheyshowanti-inflannnatOryachvihes.BasedonspeCtraldata,chenucaltransformationsandanalysisOfCDbehaviorofthelactonering,x-illosolsideandvillosolhavebeengivensmictUresland2respeCtively.[']Itisinterestingthatthesenot-eltridoidshat,ereversedstereocheAnsto'atC5andC9junCtUreSwith5Q,9Qinsteadoftheusuall}'found5…     

Synthesis of the Precursor of Tetrasaccharide from Laminin

ＳｙｎｔｈｅｓｉｓｏｆｔｈｅＰｒｅｃｕｒｓｏｒｏｆＴｅｔｒａｓａｃｃｈａｒｉｄｅｆｒｏｍＬａｍｉｎｉｎＸｉａｏＸｉａｎｇＺＨＵ；ＰｉｎｇＹｕＤＩＮＧ；ＭｅｎｇＳｈｅｎＣＡＩ（ＤｅｐａｒｔｍｅｎｔｏｆＯｒｇａｎｉｃＣｈｅｍｉｓｔｒｙ，ＳｃｈｏｏｌｏｆＰ...     

Chiral Synthesis of the Key Intermediate of Diterpenoids

(-)-Methyl(4R,5SloR)-l4-methoxyPodocmpa-8,ll,l3-triene-l9-oate(I)isthekeyintermediateforsynthesesofditerpenoidssuchaskaurenoicacid(3),kaur-l6-en-l9-ol(4),monoginol(5)('),aswellasC,,-diterpenealkaloidssuchasveachine(6),garryine(7)andatisine(8)(=).TheracemicsynthesisofthisintermediatewasdonebyK.Morietar'),butthechiralsynthesishasnotbeenreported.Herewepresentthechiralsynthesisofthiskeyintermediatefrom(R)-(+)-2-methyl-2-(2'-nitrovinyl)-5-vaierolactone(2).2wassynthesizedaccordingtoliterattirmeth…     

Studies Towards the Total Synthesis of Methyl Isosartortuoate： The Synthesis of a Cyclic Precusor of the Diene Unit

The preparation of the key intermediate 4 of the methyl isosartortuoate is described. The macrocyclization was completed through an intramolecular [ 2,3]-Wittig ring contraction. The four necessary stereogenic carbons were established by Sharpless asymmetric AE and AD reaction.     

Synthesis of the scalemic form of alkaloid (−)-dipthocarpamine

The scalemic form of active alkaloid (−)-dipthocarpamine was synthesized by asymmetric oxidation ofN-isopropyl-N′-(methylthiohexyl)urea with hydrogen peroxide in the presence of vanadium(IV) complexes with chiral Shiff's bases. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 564–565, March, 2000.     

Synthesis of the 8,19-Epoxysteroid Eurysterol A

We report the first chemical synthesis of eurysterol A, a cytotoxic and antifungal marine steroidal sulfate with a unique C8−C19 oxy-bridged cholestane skeleton. After C19 hydroxylation of cholesteryl acetate, used as an inexpensive commercial starting material, the challenging oxidative functionalization of ring B was achieved by two different routes to set up a 5α-hydroxy-7-en-6-one moiety. As a key step, an intramolecular oxa-Michael addition was exploited to close the oxy-bridge (8β,19-epoxy unit). DFT calculations show this reversible transformation being exergonic by about −30 kJ mol⁻¹. Along the optimized (scalable) synthetic sequence, the target natural product was obtained in only 11 steps in 5 % overall yield. In addition, an access to (isomeric) 7β,19-epoxy steroids with a previously unknown pentacyclic ring system was discovered.     

New Routes to the Synthesis of Mes

New　Routes　to　the　Synthesis　of　Mes...     

Synthesis of 1,3-Diols: Its Application to the Synthesis of α-Lipoic Acid

1,3-diols have been prepared from monosubstituted olefins, and the utility of this method in the synthesis of α-lipoic acid has been described.     

Synthesis of the Active Stilbenoids by Photooxidation Reaction of trans-e-Viniferin

Introduction It was reported that stilbene monomers showed multi-faced biological activities, such as antioxidation, antimutagen, antibacterial, antifungal activities.1 Espe-cially, isorhapontigenin and resveratrol showed potent inhibition on biosynthesis of leukotriene and its receptor antagonist.2 Some oligostilbenes exhibited more potent bioactivities than their monomers.3 In recent years, a number of oligostilbenes were isolated from natural sources, but a few of studies on their pharmacol…     

Studies on the Synthesis of Pyridine Analogs of the Natural Product3,5,4''''-Trimethoxystilbene

3,5,4'-Trimethoxystilbene is the methoxy precursor of a natural product 3,5,4'-trihydro- xystilbene (resveratrol)1 , which was reported to have many biological activities2. 3,5,4'-trimethoxystilbene itself is also a natural product2. We have synthesized 3,5,4'-trimethoxystilbene. In the screening of its anti-tumor activity using three different human cancer cell lines, 3,5,4'-trimethoxystilbene was found to have an IC50 5.91 mol/L for KB, 5.82 mol/L for A2780, 7.08 mol/L for HCT-8, respe…     

Investigation of the By-products Formed during the Catalytic Synthesis of 4,4＇-Methylenedimethyldiphenylcarbamate

The structures of the by-products formed during the catalytic synthesis of 4,4＇-methyldiphenylcarbamate （MDC） by the reaction of 4,4＇-methylenedianiline （MDA） with dimethyl carbonate （DMC） were identified and then the mechanisms of their formation were proposed.     

Effect of pH on the Hydrothermal Synthesis of BN Nanocrystals

Boron nitride (BN) has been synthesized using hydrothermal synthesis method. The experimental results showed that the pH value of the reaction solution has an important effect on the yield and phases of BN samples. As the pH value decreased, the content of cBN increased and the yield improved. The increase in cBN content is resulted from the conversion of oBN into cBN under hydrothermal condition, and the growth of cBN nanocrystals may due to the decrease in the reaction speed, thus the crystalline perfection of BN improved when the pH value decreased.     

A Facile Synthesis of Tetracycles of the γ-Lycorane Type

When an attempted application of the general scheme of alkaloid synthesis, based on the partial hydrogenation of 1 -alkyl-3-acylpyridinium salts and acid-induced cyclization of the resultant 2-piperideines,² to the construction of an Amaryllidaceae alkaloid system failed in the cyclization step, i.e. the transformation of dihydroisoquinoline 4a (prepared by the treatment of ester 2a ³ with 5-bromo-2 -pentanone ethylene ketal, followed by hydrogenation of the salt over palladium-charcoal) into a tricyclic ketal ester,⁴ an alternate, route of synthesis still utilizing a previously prepared isoquinoline precursor (3b) was investigated. The initial observation of the easy conversion of 3b into N-methyl (1a) and O-ethyl products (2b) was helpful in this connection.     

Synthesis of the reported structure of trans-africanan-1α-ol

A trisubstituted cyclopentane chiron has been prepared by dynamic kinetic reduction of a pulegone-derived β-keto ester. This chiron served as the starting material for the synthesis of the reported structure of the tricyclic sesquiterpene trans-africanan-1α-ol. The synthetic material was not congruent with the natural product.     

Synthesis of the D-Galactopyranoside Derivative of C_(60)

ThefascinatingsbocturesandpropertiesoffullereneshaveoPeneduPanewfieldofchendstry.Inparticular,F.Wudletal.l'2haveshownthatwatersofubleC6ocomPoundsinhibittheHITVen-zymesprotease(HIVP)andreversetranscriPtase(HIVRT).IthasbeenafocusofstUdytoinvestigatethebiologicalactivitiesofthesenovelsubstances.Fortheirpossiblemedicaluses,tolinkC6omoleculetonaturalProductssuchassugars,pephdes,amioacides,andsoonisanimPortantmethodinthisfield.Vasella3reportedthefirstglucosidederivativeofC6o'InthispaPer,w…     

Study on the Synthesis of Metabolite CM2 of Clausenamide

Synthesis of the optically active metabolite of clausenamide cm2(3,5-dihydroxy-5-(α-hydroxylbenzyl)-1-methyl-4-benzylpyrrolidin-2-one)from 3-O-acetyl-clausenamide was described.     

A New Route to the Synthesis of Ninhydrin

邻苯二甲酸二丁酯同乙酰乙酸乙酯的钠盐反应得到１，３－二酮氢化茚，再经二氧化硒氧化合成出较高收率的茚三酮。