The synthesis of diketones , and starting from diene by photochemical cyclization followed by RuO4 oxidation is described and stereochemistry of products is proposed. 相似文献
4-(N-Alkylimino)methyl-2,6-di--butylphenols (), Schiff bases of 3,5-di--butyl-4-hydroxybenzaldehyde can be oxygenated in the presence of Co(Salpr), a five coordinate Co(II)-Schiff base complex to give N-alkyl-3--butyl-5-formyl-2-hydroxy-2-pivaloyl-1,2-dihydropyridines ( as the main product together with 3-formyl-2,5-di--butyl-2,4-cyclopentadienone () and 2,6-di--butyl-4-formyl-6-hydroxy-4,5-epoxy-2-cyclohexenone (). These products result from dioxygen incorporation into the ortho position of . 相似文献
By appropriate choice of reaction conditions, the enantiomerically pure ()-(+)-2-(-tolylsulfinyl)cycloalkenone can be converted into an ()-or an ()-3-substituted cycloalkanone in good to excellent enantiomeric purity. 相似文献
Halogen cleavage reactions of -(-PhCHDCHD)Mn(CO)4, PEt3 () are studied in detail and are found to proceed either predominantly with retention or inversion, or non-stereospecifically, depending on reaction conditions. Reaction mechanisms involving SE2 (inversion), SE2 (retention) and SE (oxidative) processes are proposed, demonstrating that halogen cleavage reactions of straddle the mechanistic borderline between electrophilic substitution and oxidation processes of transition metal alkyl compounds. 相似文献
In contrast with the reaction of α-aminonitriles a, the corresponding -acylated α-aminonitriles b-f and oxalyl chloride do not yield pyrazinone derivatives, but 5-aminooxazoles - or 4(5)-imidazolones , the latter being converted in some cases into imidazo [2,1-]isoquinoline-2,5,6(3)-triones. Reactions of compounds b-f and ethyl chlorooxoacetate provide evidence for a 5(4)-iminooxazole intermediate , which aromatizes to yield 5-aminooxazoles -; however, unaromatizable īntermediates of type - isolable as 5(4)y-oxazolones after hydrolysis - undergo a catalyzed Dimroth-type rearrangement to give imidazolone derivatives . 相似文献
The title compound is the final product of the reaction between dimethylacetylene dicarboxylate and [(η5-C5H5)W(SMe) (CO)3 ]. Its molecular structure has been established by an -ray analysis based on 3301 diffractometric intensities. The crystals are monoclinic, space group 21/, with four molecules in a cell of dimensions = 10.323(2), = 16.016(2), = 10.437(2)», β = 103.56(2)°. After least-squares refinement = 0.036. The tungsten co-ordination is square-pyramidal, the apical site being occupied by the centroid of the cyclopentadienyl ring. The basal co-ordination sites contain two carbonyl groups and also the sulphur and σ-bonded carbon atoms of a chelating carbothiolic methyl ester ligand derived from the incoming alkyne and CO and SMe groups of the original complex. The W-S and σ-W-C bond lengths are 2.440(2) and 2.194(7)». 相似文献
En-route from the 5-aryl-3-hydroxy-4-nitro-cyclohexanones and , readily available from poly-enolates and 3.4-methylenedioxy-w-nitro-styrene, to dihydro-lycoricidine and to lycorine , respectively, the title compounds and are prepared in few steps. 相似文献
Calozeylanic acid has been isolated from the bark of three species: (= ), and . Its structure has been established as 2(R),3(R)-2,3-Dimetyl- 5-hydroxy-6-(3-methylbutanyl)-6-(3,7-dimethylocta-3,6-dienyl)-7-oxo-8- (2-carboxy-1-phenylethyl)-2,3,6,7-tetrahydrobenzo-4-pyrone. 相似文献
A stereoselectivity in an intramolecular cycloaddition of the olefinic -quinodimethanes 13 and 23 generated from the thermolysis of optically active 4β-[2-(4-methoxybenzocyclobutenyl)ethyl] -5α-methoxymethyl-3-phenyl-thio-methylenefuran-2-ones 12 and 22, respectively, is studied and a stereoselective synthesis of (+)--4,5-( 4-methoxybenzo) -1β,7aβ-(2α-methoxymethyl-5-oxofuro)hydrindane 1 is also described. 相似文献
Reaction of the amines (CF3)2NX (X=Cl,Br) with norbornadiene either in solvent (CH2Cl2) at ?78 °C in the dark or in the vapour phase at 20 °C in daylight gives a mixture of 3-halogeno-5-(-bistrifluoromethylamino)nortricyclene (, -and , -isomers) and -5-(-bistrifluoromethylamino)- -7-halogenonorbornene in quantitative yield formed halonium ion addition to the diene. The reaction of the amine (CF3)2NBr in solvent Me2O or Et2O at ?78 °C in the dark gives the same products in low yield, together with 3-bromo-5-alkoxynortricyclene (, - and , -isomers) and the amine (CF3)2NR (R=Me, Et) in high yield. 相似文献
The stereochemical correlation between the ene adducts 2 and 4a and their products of alkaline hydrolysis is reported. Starting from 2, by using a degradative sequence, a stereocontrolled approach to γ-amino-β()-hydroxybutyric acid (GABOB) 8f and ()-carnitine hydrochloride 8g is described. 相似文献
A new synthesis of (±)-ibogamine () and (±)-epiibogamine (), involving the intramolecular Michael addition of the keto unsaturated ester (), is described. 相似文献
The acid catalysed rearrangement of 8-methyl-pentacyclo(5.4.0.02,6.03,10.05,9)undecan-8-endo-o1 () to 3-methyl-(D3)-trishomocuban-4-o1 () provided the key step to the synthesis of the title compound (). 相似文献
The syntheses of FR-33289 (), originally isolated from a microorganism, and FR-32863 (), first designed on the basis of a biogenetic consideration and recently found to be also present in nature, are described. 相似文献
HC(SO2F)3 has been prepared and characterized. It turned out to be a strong acid, comparable to mineral acids. In aqueous solution the salts of the type Cs+C(SO2F)3? are formed. The anion, as found by crystal structure analysis contains planar CS3 configuration.Quite in contrast to these findings HC(OSO2F)3 is not even soluble in water.Derivatives of HC(SO2F)3 have been prepared so far CH3C(SO2F)3 FC(SO2F)3 ClC(SO2F)3 BrC(SO2F)3 JC(SO2F)3The heavier halogen derivatives ( Cl, Br, J ) are oxidizing agents (‘positive halogen’).A mixture of and (HO)2TeF4 is obtained if HOTeF5 and Te(OH)6 are melted together. The mixture of the isomeres have been transfered into the corresponding silylesters - and (R3SiO)2TeF4, which could be separated by fractional crystallisation and distillation.Without conformational change the pure silylesters have been reacted back to pure - (HO)2TeF4 and - (HO)2TeF4 by means of anhydrous HF. Both and (HO)2TeF4 have been reacted with ClF to give - and - (ClO)2TeF4, yellow liquids. The latter react with elemental bromine to the rather unstable and (BrO)TeF4, red liquids.Starting with -(HO)2TeF4 and XeF2 a polimer Xenon compound of the formula All materials have been characterized by melting point and vapour pressure, 19 F - nmv spectroscopy, vibrational spectroscopy, and elemental analysis. 相似文献
The principal (9, 27) and minor (17, 28) sex pheromone components of both, the Douglas fir tussock moth () and the peach fruit moth (), have been synthesized in four steps each, using the chain-lengtheningdifunctionalisation of Grignard reagents by reaction with ketenylidenetriphenylphosphorane as the key step. 相似文献
During the hydrogenation of the Δ3(3a)-4-hydrindenones or on Pd or Ni, we observe a shift of the double bond to Δ3a(7a)-4-hydrindenones and . The absolute configuration established for ketones and shows that the reaction is a suprafacial process. By deuteriation experiments, we observe that the reaction is irreversible and occurs with a molecular hydrogen exchange. 相似文献
(1,5)-(-)-Karahana ether (8,8-dimethyl-2-methylene-6-oxabi-cyclo[ 3.2.1]octane) and (1,5)-(-)-karahana lactone (8,8-dimethyl-2-methylene-6-oxabicyclo [3.2.1]octan-7-one) were synthesized from ()-3-hydroxy-2,2-dimethylcyclo-hexanone. The natural karahana lactone was shown to be almost racemic (. 1.3 % e.e.). 相似文献