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1.
A preparative route to cis- and trans-1,2-dibromocyclopropane () was developed via the Hunsdiecker reaction of silver cyclopropane-1,2-dicarboxylate (). Cis- and trans- gave the same ratio of cis- and trans- (1:3.2). The mechanism of this reaction is briefly discussed. 相似文献
2.
Masatoshi Asami 《Tetrahedron letters》1985,26(47):5803-5806
cis-4-t-Butyldimethylsiloxy-2-cyclopenten-1-ol and cis-4-tetrahydropyranyloxy-2-cyclopenten-1-ol were obtained with high enantiomeric excesses (ee) by the reaction of cis-3,4-epoxycyclopentan-1-ol derivatives with chiral lithium amide. An application to the syntheses of both ()- and ()-4-hydroxy-2-cyclopentenone was demonstrated. 相似文献
3.
Reactions of C7F15Br with elemental fluorine at 0°C have produced perfluoro--heptylbromine(V) tetrafluoride (-C7F15BrF4). This derivative of BrF5 was characterized by IR, 19FNMR, mass spectroscopy and elemental analysis. The reactions of C7F15BrF4 with 1,2-dichlorohexafluorocyclopentene-1 (C5F6Cl2) and 1,2-dichlorooctafluorocyclohexene-1 (C6F8Cl2) were used to demonstrate in the fluorinating ability of C7F15BrF4. 相似文献
4.
Treatment of the di-lithium derivative of 1,2-diethynyl-benzene () with -xylene-α,α′-diol di--toluenesulphonate () in tetrahydrofuran led to 5,12-dihydronapthacene () as the only identifiable product. This reaction presumably involves 5,12-dihydro-6,11-didehydronaphthacene () as an intermediate, and this was confirmed by the formation of 5,12-dihydro-6,11-dideuterio-naphthacene when the reaction was carried out in tetrahydrofuran-8. 相似文献
5.
2β-Fluoro-1α-hydroxyvitamin D3() was prepared from 1,2α-epoxy-cholest-5-en-3β-yl tetrahydropyranyl ether( via 2β-fluorocholest-5-ene-1α, 3β-diol(). 相似文献
6.
The photochemical behavior of -1,2-dihydrophthalide () and its 1,2-trimethylene derivative () was studied. Besides bicyclo[2.2.0]hexene formation in both cases, () transforms into its isomer () whereas () undergoes a 1,2-shift to (). 相似文献
7.
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
8.
Felix H. Cano Concha Foces-Foces Manuel Bernabe Jesus Jimenez-Barbero Manuel Martin-Lomas Soledad Penades-Ullate 《Tetrahedron》1985,41(18):3875-3886
X-Ray and 1H N.M.R. studies on pyranoid rings 1,2--fused to dioxolane rings in acetylated -gluco- and --galactopyranose derivatives demonstrate that the configuration of the dioxolane ring influences the conformation of the pyranoid ring in the -gluco but not in the -galactopyranose series. The crystal structure of 3,4,6-tri--acetyl-1,2--(R)--(l-cyano-ethylidene)-α--glucopyranose () and 3,4,6-tri--acetyl-1,2--()-(1-cyano-ethylidene)-α--galactopyranose ()have been determined by X-ray analysis. Lattice parameters for are a=20.6021 (11), b=8.0438 (2), c=5.5541 (1) Å and β= 95.588 (3)° for a cell with P21 symmetry. These parameters for are a=20.3361 (7), b=10.0907 (2), c=18.9115 (5) Å, β =112.399 (2)°, C2, with two crystallographycally independent molecules. The conformation of the pyranoid ring in both compounds can be described as flattened 4C1 and that of the dioxolane ring as distorted E1. The importance of the torsion angles for describing problems of configuration is remarked and the use of relative configurational angles is stressed. The 1H N.M.R. spectra of and and 3,4,6-tri--acetyl-1,2-O-(S)- and (R)-ethylidene-α--glucopyranose ( and ), 3,4,6-tri-O-acetyl--1,2-O-(S)- and ()-ethylidene-α--galactopyranose ( and ), and 3,4,6-tri--acetyl-1,2--()-and ()-benzylidene-α--glucopyranose ( and ) have been analyzed by using iterative computer methods and N.O.E. measurements. The results indicate that the major solution conformation of the pyranoid ring of the derivatives in the -gluco series , and may be described as flattened 4C1 and that of and as 25. The major solution conformation of the pyranoid ring in all compounds in the -galacto series (,,,) may be described as flattened 41. 相似文献
9.
Saturated and benzylic organomagnesium compounds are shown to readily undergo addition reactions with the conjugated enynes HCHCH2R′, with R′ = alkyl, OH, OC4H9, NHC25, N(C2H5)2, by refluxing for several hours in benzene or toluene.This reaction leads to both υ-acetylenic compounds (1,2-addition) and β-allenic compounds (1,4-addition). 相似文献
10.
《Tetrahedron》1987,43(20):4565-4568
Diastereomers of 2,2-disubstituted-5,6-tri- and 5,6-tetramethylenetetrahydro-1, 3-oxazin-4-ones () were synthesized from cis-2-hydroxycyclopentane and -cyclohexanecarboxamides () by condensing them with 2-butanone, 3-methyl-2-butanone, 3,3-dimethyl-2-butanone or acetophenone. The stereoselectivity of the ring closure depends on the steric requirements of the C-2 geminal substituents, although the predominant conformation (-) remains the same in both sets of the heterocycles. 相似文献
11.
Through the insertion of a carbon dioxide molecule, the oxazolidin-2-ones () and () were prepared by treataent of the salts () and () with carbonate anion on polymeric support. The hydrolysis under basic conditions of () and () afforded the erythro-3-amino-1,2-diols () and () which were fully acetylated: the 2-amino-2-deoxyerythritol derivative () was obtained in 91% yield. 相似文献
12.
Oxidation of benzotropylium () fluoborate with Na2O2 and KO2 gives the benzotropones, and , as the major products with no naphthalene () or other ring contracted products formed. Oxidation with -chloroperoxybenzoic acid produces a small amount of naphthaldehydes ( and ) and even less naphthalene, a long with the benzotropones, while oxidation with H2O2 and -butyl peroxyacetate gives slightly more of the ring contracted naphthaldehydes than benzotropones, in addition to a small quantity of naphthalene. All reactions produce some 1,2-benzotropilidene () 相似文献
13.
A novel heterocyclic sulfur ylide, 2-t-butyl-3-methyl-1-phenylbenzothiazolinium ylide () was generated as an intermediate in the reaction of 2-t-butyl-3-(nethy1benzothiazoline () with benzyne. The S-ylide underwent a novel intermolecular [1,2] shift to give 2-t-butyl-3-methyl-2-phenylbenzothiazoline (). 相似文献
14.
The dianion of dimethyl, cyclohex-4-ene-1,2-dicarboxylate () can be annelated with ethyl 4-bromobutyrate () to give cis-dimethyl 1,2,3,5-tetrahydro-1-oxo-4a(4H), 8a (8H)-naphthalenedicarboxylate (), which is readily transformed into , a synthetic intermediate for a number of sesquiterpene syntheses. 相似文献
15.
Acid-catalysed ring opening of the spirodienones () and () using p-toluene-sulphonic acid affords the styrène derivatives () and (), while treatment with acetic anhydride/H2SO4 affords the furan derivatives () and (). 相似文献
16.
T. Tanaka N. Okamura K. Bannai A. Hazato S. Sugiura K. Manabe S. Kurozumi 《Tetrahedron letters》1985,26(45):5575-5578
(5)-Prostaglandin E2 methyl ester was synthesized from ()-4--butyldimethylsiloxy-2-cyclopentenone by 2-alkenyloxycarbonylation of the organocopper conjugate-addition adduct followed by intramolecular palladium-catalyzed decarboxylative 2-alkenylation. A ()-2-butenylated cyclopentanone derivative was obtained from either 2-[()- or ()-2-butenyloxy-carbonyl]cyclopentanone derivative under the similar reaction condition. 相似文献
17.
Reaction of HCl with 3-phenylpropyne () afforded 1,2-dichloro-2- phenylpropane() among other products. The reaction proceeds by a 1,2-phenyl shift to the 5-phenyl-1-propene-2-yl cation (). 相似文献
18.
Methods of substituting pyridine by perhalogenomethylmercapto groups are discussed. The side chain chlorination of 2-(methylmercapto)pyridine leads gradually to 2-(trichloromethylmercapto)pyridine hydrochloride () and 2-(trichloromethylmercapto)pyridine (). Neither a direct reaction of pyridine with CF3SCl nor the way over a Grignard reaction or a sulfenylcarboxylate lead to CF3S-substituted products. Reactions of pyridine and bromopyridines with Hg(SCF3)2 yield 1:1-adducts () only. Lithium tetrakis(1,2-dihydro-1-pyridyl)aluminate (LDPA) reacts with CF3SCl to give 3-(trifluoromethylmercapto)pyridine (); in addition a disubstituted product can be identified massspectroscopically. 1H- and 19F-NMR-spectra are reported. 相似文献
19.
Electron-deficient aromatics, such as 2,5-bis(trifluoromethylmercapto)thiophene () or (trifluoromethylmercapto)benzene (), react with F3CSCl in the presence of F3CSO3 as a catalyst to give mainly 3-chloro-2,5-bis(trifluoromethylmercapto)thiophen () and 1-chloro-4- or 2-(trifluoromethylmercapto)benzene (, respectively. This reaction competes with the one expected to result in 2,3,5-tris(trifluoromethylmercapto)thiophene () and 1,4- and 1,2-bis(trifluoromethylmercapto)benzene (,), respectively. Further reactions of deactivated aromatics with Cl3-nFnCSCl show that the chlorine substitution is in general catalysed by strong acids. Reaction mechanisms are proposed for both Substitutions. The Cl3-nFnCS group in aromatics exerts a -M-effect in the case of an attack of a positive ion, e.g. H⊕, the well-known +M-effect in the case of reactions with positively polarized molecules, e.g. CF3Sβ+Clβ-. 相似文献
20.
Reaction of trans-1,2-dideuterioethene oxide () with carbon dioxide, using copper and nickel catalysts, and subsequent analysis of the product ethene carbonate-d2 () by microwave spectroscopy, shows that the copper-catalyzed reaction is stereo-specific (retention) whereas the nickel-catalyzed reaction is non-stereospecific. 相似文献