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1.
Raf Bussels 《Tetrahedron》2005,61(5):1167-1174
In a novel two- or three-step synthetic route, S-(1,4-phenylenebis(propane-2,2-diyl)) bis(N-methyldithiocarbamate) is reacted at low temperature with various alkyl chloroformates to form various S-tert-alkyl-N,N-alkoxycarbonylmethyl-dithiocarbamate RAFT agents. Also an alternative and novel synthetic route towards S-(1,4-phenylenebis(propane-2,2-diyl)) bis(N-methyldithiocarbamate), is proposed.  相似文献   

2.
N,N-Diethyldithiocarbamate functionnalized 1,4-polyisoprenes were prepared from 1,4-polyisoprenes (natural or synthetic). The syntheses were performed by nucleophilic addition of N,N-diethyldithiocarbamate salts upon oxirane rings of epoxidized units according to a SN2 mechanism with ring opening. Studies on model molecules of epoxidized 1,4-polyisoprene units (1,2-epoxy-1-methylcyclohexane and 4,5-epoxy-4-methyloctane) were previously achieved to develop the procedure. The best yields were obtained at low temperature in polar medium, and more especially in water with sodium N,N-diethyldithiocarbamate (DEDT-Na) as reagent. A diastereospecific addition was noted when reaction was performed in water with DEDT-Na. Afterwards, the developed procedure was successfully generalized to epoxidized synthetic polyisoprenes and epoxidized natural rubber (in THF, then in latex medium). Excellent results were obtained in latex medium with epoxidized natural rubber (ENR) latices. As with the models, a diastereospecific addition of sodium N,N-diethyldithiocarbamate trihydrate onto epoxidized 1,4-polyisoprene units of ENR was observed at the condition to bring the latex medium to pH 8 before introduction of DEDT-Na. Influence of temperature, drc, and DEDT-Na concentration were successively examined to determine the best conditions of the addition on ENR latices.  相似文献   

3.
The Me3SiCl-promoted intramolecular aminomethylation of a novel type of N,O-acetals, which were prepared via a facile three-step synthesis from N-alkylaniline derivatives and N-alkyl-2-oxazolidinones that leads to the production of pharmaceutically useful 1,4-benzodiazepine skeletons with a variety of functional groups is described. This method was successfully applied to the facile preparation of both tricyclic benzodiazepine derivatives and a 1,4-benzoxazepine derivative via 7-exo-trig cyclization.  相似文献   

4.
Ashraf A Aly 《Tetrahedron》2003,59(32):6067-6073
Reaction of 4-arylidene-2-phenyl-5(4H)-1,3-oxazolones with benzyne afforded predominantly, 3-arylidene-7-hydroxy-7-phenyl-1,4(H)-benzoxazepine-2-ones in addition to their N-phenyl derivatives. However, the reaction of the target oxazolones with an excess of benzyne gave only the N-phenyl derivatives of 1,4(H)-benzoxazepine-2-ones in good yields. The reaction mechanism describing product formation is also explained. Arylation of 1,4(H)-benzoxazepine-2-ones with benzyne proceeded successfully to give the N-phenyl products.  相似文献   

5.
Sodium iodide in acidic media has been employed for the synthesis of N-arylformamides and N-arylacetamides. The NaI/acetic acid reagent system has also been extended for the synthesis of 1,4-benzodiazepine-2,5-diones, pyrrolo[2,1-c][1,4]benzodiazepine-5,11-diones, and fused [2,1-b]quinazolinones.  相似文献   

6.
An isomerization-ring-closing metathesis (RCM) strategy afforded N-substituted 4H-1,4-benzoxazines from the protected N-allyl-2-(allyloxy)anilines. In addition, RCM was used to synthesize the N-substituted, 8-membered benzo-fused heterocycles from the respective diallyl compounds: 1,2,5,6-tetrahydro-1,6-benzodiazocine, 5,6-dihydro-2H-1,6-benzoxazocine, 5,6,9,10-tetrahydropyrido[2,3-b][1,4]diazocine and 5,6-dihydro-2H-1,6-benzothiazocine 1,1-dioxide. The isomerization-RCM approach also afforded the 7-membered ring system, 2,5-dihydro-1,5-benzothiazepine 1,1-dioxide, from the protected N-allyl-2-(allylsulfonyl)aniline. Furthermore, the structure of 1,6-bis[(4-methylphenyl)sulfonyl]-1,2,5,6-tetrahydro-1,6-benzodiazocine was confirmed by a single crystal X-ray determination.  相似文献   

7.
Recent research has revealed the presence of asparagine (Asn)-linked (N-linked) glycoproteins in certain prokaryotes. In this paper, we describe the chemical synthesis of a novel N-glycan derived from Campylobacter jejuni, a heptasaccharide composed of Asn-linked bacillosamine (Bac), repeating GalNAc, and branching Glc, namely GalNAc-α(1,4)-GalNAc-α(1,4)-[Glc-β(1,3)-]GalNAc-α(1,4)-GalNAc-α(1,4)-GalNAc-α(1,3)-Bac. The synthesis started from a Bac-acceptor, which was consecutively glycosylated with 4-O-pentafluoropropionyl (PFP) protected donors to give heptasaccharide. Reduction of azide groups was followed by debenzylation to complete the synthesis of the target oligosaccharide.  相似文献   

8.
A new family of the end-capped 5-(N,N-dimethylamino)naphthylethynyl chains were synthesized, as terminal acetylenes or poly(yne) structures, by heterocoupling between 5-iodo-N,N-dimethylnaphthalen-1-amine and 2-methyl-3-butyn-2-ol or 4-(5-iodo-1-naphthyl)-2-methyl-3-butyn-2-ol, catalyzed by the palladium-copper system. Catalytic homocoupling of the terminal acetylenes, affords to 1,4-dinaphthyl-1,3-butadiyne nanostructures. X-ray diffraction analysis of 1,4-di(α-naphthyl)-1,3-butadiyne shows that the naphthalene rings are in the anti configuration along the acetylene axis. All the conjugated compounds show an important fluorescent emission radiation.  相似文献   

9.
Related to our research on structural modifications of pentalongin, the active principle of the medicinal plant Pentas longiflora Oliv., a new synthesis of N-protected 1,2-dihydrobenz[g]isoquinoline-5,10-diones and their 4-methyl derivatives, which represent a new class of compounds, is reported. In both cases, the benz[g]isoquinoline skeleton was constructed by an intramolecular Heck reaction of N-protected 2-((allylamino)methyl)-3-bromo-1,4-dimethoxynaphthalenes and N-protected 2-((allylamino)methyl)-3-bromo-1,4-naphthoquinones, respectively.  相似文献   

10.
Jan Bräckow 《Tetrahedron》2006,62(10):2395-2404
An unprecedented method for the preparation of 4,4-disubstituted 1,4-dihydropyridines is presented. It is based on the trapping reaction of 4-substitued N-silylpyridinium ions. When performed with dialkylmagnesium reagents, such as iPr2Mg, silyl protected 4,4-disubstituted 1,4-dihydropyridines were obtained in up to quantitative yields. High 1,4-selectivity was found for sterically demanding nucleophiles, whereas small nucleophiles (Me2Mg) tend to yield 1,2-addition-products. Grignard, dialkylzinc and organocopper reagents were found to give either no addition products or less favorable results. Reduction of the obtained 1,4-dihydropyridine with NaCNBH3 in the presence of HCl, followed by treatment with tert-butyl dicarbonate provided the corresponding N-Boc protected piperidines with high yields.  相似文献   

11.
Cong Li 《Tetrahedron》2004,60(26):5595-5601
A general one-step synthesis for tris N-alkylated cyclens with good yield and unprecedented selectivity is presented. Tris and 1,4-bis N-alkylated cyclens, as the only two major products are isolated. Furthermore, according to the single crystal X-ray structures of tris and 1,4-bis N-alkylated cyclen 1 and 1a, one nitrogen atom on the cyclen ring can be protonated under this reaction condition, which prevents its further alkylation, and gives rise to the regioselectivity ultimately.  相似文献   

12.
The synthesis of 1,2,3,4-tetrahydrobenz[g]isoquinoline-5,10-dione hydrochlorides is reported starting from 1,4-dihydrobenz[g]isoquinoline-3(2H)-ones or ethyl (3-aminomethyl-1,4-dimethoxynaphth-2-yl)acetates. A third strategy relies on the synthesis of the title compounds via an N-protected 2-(3-bromomethyl-1,4-dimethoxynaphth-2-yl)ethylamine. The synthesized 1,2,3,4-tetrahydro-benz[g]isoquinoline-5,10-diones are a new class of quinones, which have not been reported yet.  相似文献   

13.
The regioselectivity in the reactions of N-arylsulfonyl-2,6-dialkyl-1,4-benzoquinone imines with arenesulfinic acids (1,6-, 6,1-, or 6,3-addition) is determined by steric factor, while in the reactions of N-aroyl-1,4-benzoquinone imines electronic effect of substituents in the quinoid ring is crucial. The reactions of N-arylsulfonyl-3,5-dimethyl-1,4-benzoquinone imines with arenesulfinic acids follow mainly the 1,4-addition pattern. N-(N-Arylsulfonylbenzimidoyl)-1,4-benzoquinone imines are capable of reacting in a way similar to both N-arylsulfonyl and N-aroyl derivatives.  相似文献   

14.
As part of our research on 2-aza analogues of pentalongin, the active principle of Pentas longiflora Oliv., the first synthesis of 2,3-disubstituted benzo[g]isoquinoline-1,5,10(2H)-triones via 3,4-disubstituted 6-hydroxybenzo[g]furo[4,3,2-de]isoquinoline-2,5(4H)-diones as the key intermediates is reported. The latter compounds have been prepared by treating 2-methoxycarbonyl-1,4-naphthoquinone with N-substituted enaminoesters under acidic conditions. These reagents are easily accessible from readily available 1,4-dihydroxy-2-naphthoic acid, β-ketoesters and primary amines. Finally, a short synthesis of substituted benzo[g]isoquinoline-1,5,10(2H)-triones is achieved by an oxidative addition of N-substituted enaminoesters onto methyl 1,4-dihydroxynaphthalene-2-carboxylate.  相似文献   

15.
The thermal degradation reactions of seven aromatic amides which are structurally related to the commercial aramids Kevlar (poly(1,4-phenylene terephthalamide)) and Nomex (poly(1,3-phenylene isophthalamide) have been investigated in the temperature range 450 to 700°C by pyrolysis/gas chromatography/mass spectrometry. Benzanilide, N,N′-dibenzoyl-1,4-phenylenediamine, N,N′-dibenzoyl-1,3-phenylenediamine, N,N′-diphenylterephthalamide, N,N′-diphenylisophthalamide, N-(4-aminophenyl)-benzamide and N-(3-aminophenyl)benzamide all gave very low yields of carbon oxides and water. The structures of the higher molecular weight products were related to those of the parent compounds and their yields are presented quantitatively. The principal mechanism for thermal cleavage of the amide bonds in the N,N′-dibenzoylphenylenediamines is mainly heterolytic, while for the other compounds thermal cleavage of the amide bonds is homolytic. The relationship between the pyrolysis products of the model compounds and those of the corresponding aramids is discussed.  相似文献   

16.
Biologically important pyrazolylpyridines were synthesized in excellent yield by the oxidation of pyrazolyl 1,4-dihydropyridines (pyrazolyl 1,4-DHPs) using tetrapropylammonium perruthenate/N-methylmorpholine-N-oxide (TPAP/NMO) under mild conditions at 0 °C.  相似文献   

17.
A stereoselective synthesis of 1,4-dideoxy-1,4-imino-d-allitol 1 and formal synthesis of (2S,3R,4S)-3,4-dihydroxyproline was achieved via the addition of vinylmagnesium bromide to the benzylimine derived from (R)-2,3-O-isopropylidene glyceraldehyde followed by N-allylation, ring-closing metathesis (RCM), and dihydroxylation.  相似文献   

18.
《Tetrahedron letters》2004,45(4):719-722
A stereodivergent synthesis of 1,4-dideoxy-1,4-imino-d-mannitol I and d-allitol III from an (S)-glyceraldimine, which is easily prepared from d-mannitol, has been achieved with overall yields of 62% and 49%, respectively. The synthesis is based on the addition of vinylmagnesium bromide to N-benzylimine 1, derived from readily available (R)-2,3-O-isopropylideneglyceraldehyde, followed by N-allylation or N-acryloylation, ring-closing metathesis and asymmetric dihydroxylation.  相似文献   

19.
In the process of stabilization against the autooxidation of hydrocarbons, the more effective of the two title antioxidants, i.e. N-iso-propyl-N′-phenyl-1,4-phenylenediamine (Ia), is transformed into N-iso-propyl-N′-phenyl-1,4-benzoquinonediimine (IIa). The stability of (IIa) is reduced in an acid medium. In an inert atmosphere and in the presence of weak acids (IIa) reacts quickly with 2,6-di-tert-butylphenol, giving rise to 3,3′,5,5′-tetra-tert-butyl-4,4′-biphenyldiol (VI) and 2,6-di-tert-butyl-4-(4-phenyl-aminophenylamino)-2,5-cyclohexadiene-1-one (Va). In the presence of a relatively low amount of oxygen (Ia), 3,3′,5,5′-tetra-tert-butyldiphenoquinone (IV), (Va) and 2,6-di-tert-butyl-1,4-benzoquinone (VII) are formed. In this way, conditions for co-operative action between the two antioxidants are provided. In the absence of acids the reaction proceeds much more slowly and (Va) is not formed. The mechanism of formation of all the compounds is discussed. There is no pronounced synergism between (Ia) and 2,6-di-tert-butylphenol during the autooxidation of squalene (natural rubber model) in pure oxygen and in a neutral medium. In the presence of 1 vol. % of acetic acid the effectiveness of antioxidant (Ia) is strongly reduced, particularly at elevated concentrations. In a mixture of (Ia) with 2,6-di-tert-butylphenol, a pronounced co-operative effect can be observed.  相似文献   

20.
N-Aroyl-3,5-dimethyl-and N-[N-arylsulfonylbenz(acet)imidoyl]-3,5-dimethyl-1,4-benzoquinone monoimines react with hydrazoic acid according to the 1,4-addition pattern. N-Acyl-2,3,5,6-tetrachloro-1,4-benzoquinone monoimines take up hydrazoic acid at the double C=N bond (1,2-addition).  相似文献   

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