Studies on Agarofurans Ⅳ. The Synthesis of 4-Substitutioned Agarofurans

Agarowoodoilwasfoundtobebioactiveinpharmacologicalscreeningforthenervoussysteminourinstitute.AgarofuransareonesmicturaltypeoftheimportantconstituentSofagarowoodoil.Q-Agarofuran(lh),oneofthemanyconstitUentsoftheoil,issuspectedofbeinganimportantcontributortothebioactivity.AlthoughseveralsynthesisofQ-agarofuran(fo)havebeendescribed'-',theyarenotsuitableforthesynthesisofitsanalogs.Thebioactivitiespromptedustodevelopanewroutetoa-agarofuran(fo)anditsanalogs.EarliersynthesisofQ-agarofuran(lb),with…     

Studies on Agarofurans VIII. Synthesis of the Metabolites of 4-Butyl-a-agarofuran

Agarofurans have been found to be active on the nervous system in our institute. 4-Butyl-a-agarofuran 1 is a promising drug candidate. In order to explore the pharmacokinetics of 1, the metabolism of 1 in vitro was studied with liver microsomes from rats. Five metabolites were isolated and structures were identified as compounds 2-6. But the absolute configuration of 2,4,5 and the position of carbonyl in 3 could not be unambiguously determined. Further determination was limited by the smal…     

Studies on Agarofurans Ⅰ. New Synthesis of Nor-Ketoagarofuran and 4-Hydroxydihydroagarofuran

Nor-ketmpofuran(1)and4hydroxydih~(2)areboofthehanoidsisoatedfrOIn~~oil,~nedfromthetwinfectedPlanAguiIboaagaIIOCaROxb(1).AlthoUgbtheSynthesisOfnor-ket-ran(1)hasthendescrind'),itishighlyrestriCtedtyitsPr~r,p-grofiiran.ThebiOaCtivityofmp-onthenervous-SystemhasbenfoundQ).Nor-ketOagarOfuran(1)InayalsoPOSSeSshi~vity,anditisaedintermAnatefOrfurthermedcation.Thusitwasdeemedwerth-chletOsearhfOrnewroUtestonor-ket~ran(1).Schemel.afM-CPBA,CH-2Cl2,btLmEtO,cfPCC,ChiCl2,d'LmAlC1$EtOOUr…     

Studies on Agarofurans Ⅱ.Stereoselective Synthesis of 1α-and 1β-Methyl Agarofuran

AgarOfuransPOssessbioactivityonthenervous-System('>.InordertoinvestigaetherelationbetWeenthesiteOfsubstituentsandthebioactivity,weplannedtointroducesubstitUentsontoseveralchosensites.HerewedescribetheSynthesisofla-andlp-methy1grofuran1and2,WhichhavenotbeenpreviouslyrePOrted.Thekeyintermediatesenroutetogrofuranland2wereenone3and4.OUrinitialroutewasreaCtionofdihydrocarvone(6)with3-pentene-2-one(1O)toaffordaAnxtUreof3and4withoutemPhasizingthestereochendStry(Schemel).ReduCtionofcarvone(5)…     

Studies on Agarofurans Ⅷ.Synthesis of the Metabolites of 4—Butyl—α—agarofuran

The structures of five metabolites (2-6) of agarofuran 1 were confirmed by synthesis. The configuration of the secondary hydroxyl in 7 was determined by Horeau′s method. The configuration of C-2 in compound 4 and 5 was determined by their stereochemistry and NMR.     

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…     

Studies on Synthesis of Diadenylyl Sulfites

Diadenylyl sulfites were obtained by the condensation of protected adenosines using O,O-bis (1-ben-zotriazolyl) sulfite as a coupling reagent.     

Studies on the Synthesis of Villosol

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

Studies on the Sulfinatodehalogenation Pt.30:Synthesis of Trifluorovinyl Compounds

Trifloorovinylcompoundswereusefulmonomersusedwidelyinthepolymerfield.Synthesisofsuchcompoundsattractsmuchattention.Functionalizedtrifluorovinylcompoundshaveuniquepropertiesasmonomersinpolymerizationandcanbeexpectedtoundergoselectivereactionsatthetrifluorovinyloratthefunctionalgroupsite.lHowever,fewpapershaveappearedonthepreparationofsuchcompounds.2'3InthecontinuingstudyonthesulfinatodehalogenationofBrCF2CFClR,aseriesoftrifluoroalkylcompoundswereobtained.Hereinwereporttheresults.Treatmentof…     

The Kornblum Reaction of α-Substituted 3-Benzyl-1,2-dihydro-2-oxoquinoxalines. Synthesis and Structure of 3-Benzoyl-2-oxo-1,2-dihydroquinoxaline

A method has been developed for the preparation of 3-benzoyl-2-oxo-1,2-dihydroquinoxaline by the reaction of 3-(-chlorobenzyl)-1,2-dihydroquinoxaline under Kornblum reaction conditions to the corresponding -azido derivative and then acid fission of the latter. The structure of the target ketone has been confirmed by X-ray analysis.     

Studies on The Application of The Paternò-Büchi Reaction to The Synthesis of Novel Fluorinated Scaffolds

In the context of new scaffolds obtained by photochemical reactions, Paternò-Büchi reactions between heteroaromatic, trifluoromethylphenyl ketone and electron rich alkenes to give oxetanes are described. A comprehensive study has then been carried out on the reaction of aromatic ketones with fluorinated alkenes. Depending on the substitution pattern at the oxetane ring, a metathesis reaction is described as a minor side process to give mono fluorinated alkenes. Overall, this last reaction corresponds to a photo-Wittig reaction and yield amid isosteres. In order to explain the uncommon regioselectivity of the Paternò-Büchi reaction with these alkenes, electrostatic-potential derived charges (ESP) have been determined. In a second computational study, the relative stabilities of the typical 1,4-diradical intermediates of the Paternò-Büchi reaction have been determined. The results well explain the regioselectivity. Further transformations of the oxetanes or previous functionalization of the fluoroalkenes open perspectives for oxetanes as core structures for biologically active compounds.     

Studies on Glycosides VI. Facile Synthesis of Alkyl α-and β-D-Glucopyranosides

A facile Method for the synthesis of alkyl α- and β-D-glucopyranosides using 1-0-trimethylsilyt-2,3,4,6-tetra-O-benzyl-α-D-glucopyranose by the promotion of BF₃ET₂O was reported. The mixture of α -and β-anomers, in which β-anomers predominated, was obtained in good yields.     

The Synthesis of Single Crystals of Manganese Aluminophosphate Molecular Sieve and Studies on Their Properties

Single crystals of the molecular sieve, MnAPO-5, were synthesized by hydrothermal synthesis in the presence of fluoride ions. It was shown by X-ray diffraction, infrared spectroscopy, electron paramagnetic resonance spectroscopy, electron probe analysis and chemical composition analysis that the structure of MnAPO-5 is of the A1PO-5 type, and manganese(Ⅱ) is incorporated into the framework. Adsorption properties, thermal stability and surface acidity were also investigated.     

A General Synthesis of α-Substituted Acrylonitriles

During a study of synthetic approaches to naturally-occurring sesquiterpene lactones, a new synthesis of the α-methylene-y-butyrolactone group was developed¹ and has subsequently been applied to the synthesis of various types of α-methylenecarbonyl compounds.² The synthetic scheme suggested that α-substituted acrylonitriles would also be available by this method.     

Chemical Studies on Decahydroacenaphthylene Compounds-Studies on the Synthesis of Hainanolide-Construction of Tricyclic Intermediate

Underthenamesofharrigtonolideandhainanolide,(I)wasobtainedindependentlybyButalandSunZfromdifferentspieces.Itwasdemonstratedsignificalltamivirusandantitumoractivityinvitroandvivotest3.ThecomplicateandnoveltypeofstructurewouldbeagreatchallengetostUdyitstotalsynthesis.Itcanbeobtainedfromhainanolidol(II),theanalogueof(I)isolatedfromCHainannesisL.,byPh(OAc).'.Aretro-syntheticschemethroughatricycliccompound(ill)hasbeendesigned.Inordertoobtaintheintermediate(lll),asyntheticrouteseemedtobereason…     

Studies on macrocyclic diterpenoids Ⅴ.Synthesis of(±)-sarcophytol-A benzyl ether

The title compound,sarcophytol-A benzyl ether has been synthesized through 13 stepsby employing acetone and geraniol as starting materials.The key steps in the synthesis weredouble bond migration reaction of allylic alcohols 5 and 6,phase transfer catalytic coupling(PTC)reaction of Ⅱ with 7 and the cyclization reaction of dicarbonyl acyclic precursor inducedby TiCl_3-AlCl_3(3:1)/Zn-Cu system.     

Studies on O-,N-Acylation of 3-Hydroxyisoxazole and Their Regioselective Synthesis(Ⅰ)——O-,N-acylation of 5-Methyl-3-hydroxyisoxazole with 2,2-Dimethyl 3-Substituted Cyclopropanecarboxylic Chlorides

The reactions of 5-methyl-3-hydroxyisoxazole with 2, 2-dimethyl, 3-substituted cyclopropanecarboxylic chlorides give O-acyl-5-methyl-3-hydroxyisoxazole and N-acyl-5-methylisoxazolin-3-one derivatives. The ratio of O-acyl to N-acyl product depends upon the acylation reagents. O-acyl derivatives can be converted to the N-acyl compounds by isomerization under acidic conditions or heating.     

Studies on Synthesis and Properties of Mg-Al-nitrate Layered Double Hydroxides

Layered double hydroxides (LDHs), or the so-called hydrotalcite-like compounds, are important clay materials owing to their intercalation ability of anionic species and other physicochemical properties for application as anion adsorbents, medicine stabilizers, ion-exchangers, ionic conductors, catalysts and catalyst supports 1-2. The general formula is, [MⅡ1-x MⅢx(OH)2]x+ [Xm-x/m·nH2O]x-, abbreviated by: [MⅡ-MⅢ-X]. The net positive charge, due to substitution of trivalent by divale…     

Studies on Atropo-Enantioselective Synthesis of the Natural Chiral Axial Biaryls

Ary-aryl bond formation plays an important role in modern organic synthesis. These bonds are very often occurred in natural products such as alkaloids as well as in numerous biologically active parts of pharmaceutical and agrochemical specialties. In addition, they are also the scaffolds of some of the most efficient and selective ligands for asymmetric catalysts, especially when atropisomery is possible. In this report, we report the structure and the enantioselective synthesis of some natura…     

L-Proline Catalyzed Solvent-Free Knoevenagel Condensation for the Synthesis of 3-Substituted Coumarins

L-Proline was utilized as an efficient organo-catalyst for the environmentally benign synthesis of 3-substituted coumarins by the Knoevenagel condensation of substituted 2-hydroxybenzaldehydes with reactive methylene compounds under solvent free conditions.