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1.
As a kind of intermediates, a-oxo ketene dithioacetals I are important in organicsynthesis"'. In our recent studies, we found that the difference of dialkythio group canbestow various properties on these kinds of compounds"'. To exploit the reactivityadjusted by the dialkythio groups in l, a-oxo ketene dibenzylthioacetals 2 were chosenand studied. Some interesting new results were obtained in these experiments. Here wereport the new results.When studying the reaction of a-oxo ketene dibenzylt… 相似文献
2.
Asaversatilethree-carbonsynthon,a--oxoketenedimethylthioacetalsIhavebeenappliedinmanyfields'.Inourpreviousworks'-',someproperties,especiallyadditionselectivity,ofthearoxoketenecyclicdithioacetals2werefoundtobequitedifferentfromthoseof1.Herea--aroyl... 相似文献
3.
α-Oxo Ketene Dithioacetals Chemistry-A Facile Route to the Synthesis of Fused Heterocyclic Compounds
Q-Oxo ketene dithioacetals and related compounds are versatile synthons in organicsynthesis'-'. The substitution reaction of or-oxo ketene dimethylthio acetals with diamineis one of the impel'tant applications for the synthesis of corresponding a-oxo ketenecyclic N, N-acetals. Junjappa and co-workers described this reaction ill a review'.However, since some kinds of ketene dimethylthio acetals are not easy to prepare, themethod melltioned above is limited. Zhu and co-workers had successfully… 相似文献
4.
ac-oxo-ketenedithioacetalsandrelatedcompoundsareversatileSynhlonsinorghocsynthesis.'"Althoughtherehavebeennumerousreportsaboutmisfieldinrecentyears,l-6allofthestUdiescanberoughlydividedintotwoaspectsfoneistheapplicahonofac-oxo-ketenedithioacetalsinorganicsyntilesis,andtileoilleristilesindiesontilereachvityadjustCdbythedialkylthiogroupsinac-oxo-betenedi1illoacetals.WehavedevotCdoureffortstothelatter."82-(l,2-ethylenedithio)medlylene-3-oxo-5-aryl-4-pentenoacids3wereformedbycondonsahonofacylketC… 相似文献
5.
Intramolecular Induction of Asymmetric Darzen's Condensation of Aldehydes with Chiral α-Chloroacetates 总被引:1,自引:0,他引:1
《中国化学快报》1999,(6)
Inconvergentwithourinterestintheasymmetricsynthesisofnaturalproducts,intramolecularinductionofasymmetricDarzen'scondensationlofaldehydeswithQchloroacetatesofchiralalcoholswasstudies,asshowninScheme1.Scheme1.R*OH CICH,COCI~CICH,COOR*i(-)-menthol(450%)3( )-Jsomenthoi(i56%)5(-)-8-phenylmenthoi(74%)2( )-neomenthol(147%)4( )-f6nchol(478%)6(-)-8-11-naphthylmenthoi(99%)I-henumbersintileparenthesisilldicatedthece%oftilecorrcspondillgmethy13-pllcn}lgl}'cidatcobtainedh\'trallscstcrltiationBenza… 相似文献
6.
Aryl-substitutedpyrazolederivativeshavealreadyattractedwideattentioninrecentdecadesbecausetheywerereportedtoshowabroadspectrum0fbi0logicalactivities.Forinstance,severalsubstitutedpyrazolyIpyrazoIesdemonstratedhighpreemergentherbicidalactivityagainstawidevarietyofbroadleafweedspecies"'.Pyraz0lyl-pyrimidinesexhibiteds0mefungicidalactivity'.Fripronil(5-amino-3-cyan0-l-(2',6,-dichloro-4'-trifluoromethylphenyisanewpyrazoleinsecticidethatprovidesexcellentc0ntrolofmanysoilandf0liarinsects0nawidevari… 相似文献
7.
Under basic conditions,a series of 4,4-dialkylthio-1,2-diaza-1,3-butadienes were synthesized in good to excel-lent yields via a novel azo-coupling decarboxylation reaction by reacting α-carboxyl ketene dithioacetals witharyldiazonium salts in aqueous medium. 相似文献
8.
I. P. Lokot' F. S. Pashkovskii F. A. Lakhvich 《Chemistry of Heterocyclic Compounds》2001,37(6):707-714
A method is proposed for obtaining 3- and 5-alkyl-6-alkyl(aryl)tetrahydropyran-2,4-diones based on the condensation of the dianion of alkyl(dialkyl)acetoacetic ester with aldehydes and ketones. 相似文献
9.
It is reported that alkali-metal borohydrides(MBH4, M = Li, Na and K) are efficient catalysts for ring opening polymerization(ROP) of α-amino acid N-carboxyanhydrides(NCAs). Polypeptides are prepared in quantitative yields with relatively narrow molecular weight distributions(MWDs = 1.1~1.5) which depend on the reaction temperature. End groups of the produced polypeptide are studied in detail by MALDI-ToF MS, 1H-NMR, 13C-NMR, 1H-1H COSY and 1H-13C HMQC analyses. The results indicate that α-hydroxy-ω-aminotelechelic polypeptides are formed which are suitable for postpolymerization functionalization. 相似文献
10.
Microwaveirradiationhasf0undalotofapplicati0nsinrecentyears'".Thereactiontimecanbeshortenedgreatlyundermicrowaveirradiation,soitisanewandconvenientsyntheticmethod.Inprevi0uspapers"',wereportedtheethoxylationsofnitro-chlorobenzeneandreactionsofcarboxylicacidwithhalidesunderndcrowaveirradiation.a,6-Unsaturatedketonesareusefulcompounds,whosesynthesiswerenoteasybyconventionalways"9.Ontheotherhand,KF-Al2O3isanewkindofbasecatalyststhatcancatalyzemanyreactionsunderndldconditions,t0givehighcatalytic… 相似文献
11.
A new method for the synthesis of substituted thiophenes was through intramolecular aldol condensation of α-oxo ketene dibenzylthioacetals.All products were confirmed with IR,1H NMR and elemental analysis. 相似文献
12.
13.
Haifeng Yu 《中国化学》2012,30(2):367-371
Using 2‐[bis(alkylthio)methylene]‐3‐oxo‐N‐o‐tolylbutanamides 1 as odorless thiol equivalents, an efficient and odorless synthesis of thioethers has been developed. Promoted by NaOH in EtOH, the cleavage of 1 commences to generate thiolate anions, and the generated thiolate anions then react with halides to give various thioethers in good yield. It is noteworthy that only a very faint odor of thiols can be perceived during both the reaction and the workup. 相似文献
14.
Due to the chemoselective dehalogenation by SmI2, the addition of a-halomethylsulfones to carbonyl compounds afforded ,β-hydroxysulfones. Those reactions with α-bromomethylsulfones gave the products in moderate to good yields. The SmI2-mediated addition of gem-dihalomethylsulfones to ketones also afforded α-halo-β-hydroxysulfones in moderate yields. 相似文献
15.
α-Bromo chalcones containing 2-thiene ring were prepared in good yields by the condensation of 1-(thien-3-yl)ethanone with aromatic aldehydes, followed by bromination with bromine and selective dehydrobromination with triethyl amine at room temperature. 相似文献
16.
Lophenol, cholest-4α-methyl-7-en-3β-ol (1), obtained from Dracaena cochinchinensis (Lour.) S. C. Chen, was structurally modified. It was acetylated to protect 3β-hydroxyl group, and then oxidised by selenium dioxide in acetic acid to give cholest-4a-methyl-8-en-3β, Ta-diol diacetate (3). This compound 3 is unstable in chloroform solution or when heated and easily converted to a diene compound, cholest-4a-methyl-7,14-dien-3β-ol acetate (4). The structures of 3 and 4 were elucidated by means of IR, ^1H NMR, ^13C NMR and MS, and the absolute configuration of 3 was established by X-ray crystallography. The property of 3 was also discussed in this paper. Both 3 and 4 are new compounds and were reported for the first time. 相似文献
17.
A series of homoallyl β′,γ′-unsaturated amines were synthe sized via 1,2-addition of α,β-unsaturated imines with allylsamarium bromide in excellent yields under mild and neutral conditions. 相似文献
18.
A new approach to the synthesis of α,β-unsaturated ketones from 1,2,3-trimethyl benzimidazolium salt via the condensation reaction with aldehydes followed by the addition reaction of Grignard reagents with quaternary C=N bond was provided. 相似文献
19.
The cross-coupling reaction of trans-alkenylboronic acids with a-bromoacetic esters was firstly studied. It was found that using Pd(OAc)2 as catalyst, a bulky electron-rich phospine, (2-dicyclohexylphospino-biphenyl) as ligand, the reaction can be readily accomplished to give specific (E)-b,g-unsaturated esters in high yields. 相似文献