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1.
A facile synthetic route for benzimidazoles, benzothiazoles and benzoxazoles comprising the reaction of corresponding o-phenylenediamine, o-aminothiophenol and o-aminophenol with various aldehydes using silica supported nano-copper (II) oxide as a catalyst has been described. The catalyst exhibited a clean reaction profile with excellent yields in a short reaction time. The catalyst can be recycled effectively after use.  相似文献   

2.
It was found that lanthanum metal caused the dehalogenation of o-dihalogen substituted arenes and α,α′-dihalogen substituted o-xylenes to generate the corresponding benzynes and o-quinodimethanes. When o-dihalogen substituted arenes were allowed to react with lanthanum metal in the presence of dienes, the Diels-Alder products between benzyne and dienes were formed in moderate to good yields. Similarly, the Diels-Alder adducts of o-quinodimethane with dienophiles were obtained, in the reaction of α,α′-dibromo-o-xylenes with lanthanum metal in the presence of dienophiles.  相似文献   

3.
The oxidation of benzidine, o,o′-tolidine, and o,o′-dianisidine by manganese dioxide was studied in an acidic medium. It has been shown that the studied substances are quantitatively oxidized by the reagent to the corresponding quinonediimines and that this reaction can be utilized for the indirect titrimetric determination of benzidine and o,o′-tolidine, based either on ferrometric titration of unconsumed manganese dioxide or on ascorbinometric titration of the quinonediimine formed.  相似文献   

4.
The Knudsen-cell mass-spectrometric method has been used to study reactions of the type: M(g)+Li(g) = MLi(g) and M(g)+Li2(g) = MLi(g)+Li(g), where M = Sm, Eu, Tm or Yb. The dissociation energies (in kJ mol?1) of the gaseous lithide molecules determined from the measured reaction enthalpies are: Do0(SmLi) = 45.3±4.5. Do0(EuLi) = 63.2±3.0. Do0(TmLi) = 65.1±3.5 and Do0(YbLi) = 33.4±3.0.  相似文献   

5.
A commercially available collection of β-amino alcohols have been converted to their corresponding β-(o-diphenylphosphino) benzoyloxy(o-diphenylphosphino) benzamides and have been employed in the Tsuji–Trost asymmetric alkylation reaction with 1,3-diphenylpropenyl acetate. The best ligand was derived from l-tert-leucinol and when applied to the asymmetric allylic alkylation reaction, yielded the product in an enantiomeric ratio of 99.5:0.5 favoring the (S)-enantiomer.  相似文献   

6.
5-(4-Methylpiperidino)methyl-2-thiouracil (1) has been obtained via the Mannich reaction between 2-thiouracil, paraformaldehyde, and a cyclic secondary amine such as 4-methylpiperidine (4-MP) in ethanol. New S,N(1)-di-o-(m- and p-)bromo-(nitro-) benzyl-substituted derivatives have been synthesized successfully in the reactions of 1 with the corresponding o-(m- and p-)bromobenzyl bromides or o-(m- and p-) nitrobenzyl chlorides in DMF solution in the presence of K2CO3. The opposite method of synthesis, that is, the reaction between 2-o-(m- and p-)bromobenzylthio-1-o-(m- and p-)bromobenzyluracils and 2-o-(m- and p-)nitrobenzylthio-1-o-(m- and p-) nitrobenzyluracils (8), with paraformaldehyde and 4-methylpiperidine in ethanol failed, indicating the important role of the enol form of 2-thiouracil for the Mannich reaction to be successful.  相似文献   

7.
The oxidation of benzidine, o-tolidine, and o-dianisidine with chloramine T and N-bromosuccinimide was studied, the stoichiometry was established, and a mechanism was proposed. An extraction-photometric determination of these diamines was developed, based on the reaction with excess chloramine T or N-bromosuccinimide and the measurement of the absorbance of the N,N′-dihalogeno-diphenoquinonediimines formed, after their extraction into chloroform.  相似文献   

8.
The reaction of dimethyl(methylthio)sulfonium trifluoromethanesulfonate (DMTST) with o-allylphenol gave 2-methylthiomethyl-2,3-dihydrobenzofuran in 97% yield. The reaction of DMTST with N-tosyl-o-isopropenylanilide followed by the addition of aq sodium carbonate afforded N-tosyl-3-methylindole in 88% yield, whereas N-tosyl-o-vinylanilide afforded N-tosylindoline in 85% yield.  相似文献   

9.
The well-known failure of the Hammett Ho function to describe the prototropic reaction isotherms of aromatic carboxamides can be corrected by taking account of the hydration requirements of the prototropic reactions of the carboxamides relative to the hydration requirements of the dissociations of the primary amines used as indicators to establish the Ho scale. This approach has been successfully applied to benzamide and the naphthamides. For up to a 4:1 molar ratio of water to sulfuric acid, the amide acidity scale, HA and the Ho scale are simply related by HA = Ho — 2 log aw , where aw is the activity of water.  相似文献   

10.
A convenient procedure has been proposed for the synthesis ortho-vinylbenzyl-substituted ethers, amines, and sulfides via reaction of o-(2-bromoethyl)benzyl bromide with various nucleophiles.  相似文献   

11.
《Tetrahedron》2003,59(36):7189-7201
The title reaction, carried out in DMF in the presence of triethylamine or potassium carbonate, has furnished the ‘expected’ 3-amino-2-nitrobenzo[b]thiophenes 2o together with the ‘unexpected’ 2-amino-3-nitrobenzo[b]thiophenes 3o, thus recalling the situation observed with other weak nucleophiles in the presence of non-nucleophilic bases. The effects (electronic as well as steric) of the ortho-substituent (OH, NH2, OMe, Me, Et, F, Cl and Br) on the course of the reaction have been investigated, determining their influence on yields and product ratios (2o/3o). An analysis of 13C NMR and MS spectra of 2o and 3o has been carried out. Ab initio computations on 2of, 2oi, 3of and 3oi at DFT level have furnished informations on their geometry and stability in the gas phase, thus allowing to assign a role to their stability on the course of the reaction as well as on some EI-MS results.  相似文献   

12.
In the present study, new benzimidazole, benzoxazole and benzothiazole derivatives were prepared and screened for antimicrobial activity. The structure of 4,4′-((6-(4-(diethylamino)phenyl)-1,3,5-triazine-2,4-diyl)bis(oxy))dibenzaldehyde (DIPOD) 5 was established from p-hydroxy benzaldehyde 4 and 4-(4,6-dichloro-1,3,5-triazin-2-yl)-N,N-diethylaniline 3. The reaction of DIPOD 5 with different o-phenylenediamine or o-amino phenol or o-amino thiophenol in ethanol gave benzimidazole, benzoxazole and benzothiazole 7. Novel heterocycles showed excellent broad-spectrum antimicrobial activity against bacterial strain (Escherichia coli, Staphylococcus aureus) and fungal strain (Candida albicans, Aspergillus niger) cultures. Activity data was compared with standard Streptomycin and Fluconazole drug. Photophysical and thermal properties of synthesized compounds were also studied.  相似文献   

13.
Systems consisting of metal (Al, Ti, Zr) tert-butylate and tert-butyl hydroperoxide oxidize 3,6-di-tert-butyl-o-benzoquinone under mild conditions (room temperature, benzene). With (t-BuO)3Al and (t-BuO)4Zr, the major reaction products are 5-hydroxy-3,6-di-tert-butyl-2,3-epoxy-p-benzoquinone, and with (t-BuO)4Ti, 2-hydroxy-3,6-di-tert-butyl-p-benzoquinone. Under the conditions of this reaction, 3,6-di-tert-butylpyrocatechol initially transforms into 3,6-di-tert-butyl-o-benzoquinone. The reactions involve metalcontaining peroxides.  相似文献   

14.
A rhodium complex Rh2(OAc)4 catalyzed the reaction of nitrobenzenes and diphenylphosphine oxide HP(O)Ph2 giving o-(diphenylphosphinoyloxy)anilines predominantly, which were accompanied by small amounts of the p-isomers. Nitorobenzenes possessing a bulky o-substituent, particularly o-(t-butyl)nitrobenzenes, underwent the reaction in high yields. The reaction is considered to involve the reductive formation of O-phosphinoyl-N-arylhydroxyamines from nitrobenzenes, and o-phosphinoyloxylation by the rearrangement.  相似文献   

15.
Fan Yang  Junli Zhang  Yangjie Wu 《Tetrahedron》2011,67(16):2969-2973
An efficient and facile synthesis of isoquinolines has been described via a tandem reaction of imination of o-halobenzaldehydes with tert-butyl amine and subsequent palladacycle-catalyzed iminoannulation of internal alkynes. This tandem reaction could be carried out successively in one pot without any special operation, and the annulation step could afford isoquinolines derivatives in moderate to good yields with high regioselectivity. In addition, the simple synthesis of indoles was realized by palladacycle-catalyzed annulation of o-iodoaniline or o-bromoanilines with internal alkynes.  相似文献   

16.
The o-halogenophenylacetylenes o-iodophenylacetylene,o-bromophenylacetylene and o-chlorophenylacetylene can be prepared by regiospecific reaction of iodine, bromine, and hexachloroethane respectively with the dianion of phenylacetylene.  相似文献   

17.
A [4+3] annulation of o-phenylenediamines with primary nitroallylic acetates affords nitrobenzodiazepines (NBDZs) in good to excellent yield. The reaction which proceeds in MeOH at room temperature in the absence of any base or catalyst involves a cascade SN2 N-nitroallylation-intramolecular aza-Michael addition sequence. In the case of mono-N-arylated o-phenylenediamines and o-aminobenzamides, the reaction stops at the SN2 stage affording nitroallylic amines. On the other hand, reaction of o-aminobenzamides with secondary nitroallylic acetates delivers SN2′ products. Formation of stable SN2 and SN2′ products provides insights into the reactivity of primary and secondary nitroallylic acetates and also the mechanism of formation of nitrobenzodiazepines.  相似文献   

18.
Condensations of o-halo-substituted benzenesulfonyl chlorides with 2-aminopyridines and amidines may give the corresponding 1,2,4-benzothiadiazine-1,1-dioxides under mild, non-catalytic conditions in nearly quantitative yields. The successful one-pot cyclization depends on three factors: (i) the nature of the o-halogen, (ii) the electronic character of the benzene ring substituent, and (iii) the steric load around the amidine unit. O-Fluorobenzenesulfonyl chlorides bearing methylcarboxyl- or nitro-group and o-chloro- and o-bromobenzenesulfonyl chlorides bearing nitro-group are reactive enough to give the desired 1,2,4-benzothiadiazine-1,1-dioxides in a one-pot base-promoted reaction. In all other cases, open-chain sulfonylated amidine intermediates are isolated. The latter are converted to the title compounds either in the presence of potassium carbonate or upon the addition of a copper(I) catalyst.  相似文献   

19.
Formation of both sila-functional and carbo-functional phenoxasilins from diphenyl ether and o,o′-dibromodiphenyl ether precursors is described. Tricyclic oxasilepins are formed from o,o′-dibromobenzylphenyl ether by metallation with n-BuLi followed by reaction with dichlorosilanes as well as by ring expansion of an appropriate phenoxasilin. Reactions at the silicon center and at the ring methylene carbon of the oxasilepins are reported, as well as attempts to generate oxasilocins.  相似文献   

20.
On the basis of the reaction of ethynediylbisphosphonates and chloroethynylphosphonates with classical donor alka-1,3-dienes, a general strategy for synthesis of o-bisphosphanylbenzenes and o-chlorophosphanylbenzenes, which includes two consecutive steps: Diels-Alder condensation → aromatization of the carbocyclic phosphonate (bisphosphonate) formed → reduction of the phosphonate groups, was developed. Convenient procedures are devised for aromatization of phosphorus-containing cyclohexa-1,4-dienes and for reduction of o-phenylenebisphosphonates and o-clorophenylphosphonates to primary phosphines. A series of new alkylsubstituted phosphonic chlorides were prepared, and a possibility of functionalization of methylsubstituted o-phenylenebisphosphonates and o-clorophenylphosphonates by the methyl groups is demonstrated.  相似文献   

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