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1.
《Tetrahedron》2011,67(29):5304-5318
Di-, tri- and tetra-alkenylindoles were prepared by palladium(0)-catalyzed Heck cross-coupling reactions of di-, tri- and tetrabromo-N-methylindoles. The reactions were carried out at 90 °C using a novel biaryl monophosphine ligand developed by Buchwald and co-workers. 1,2-Dihydrocarbazoles were formed by a domino ‘twofold Heck/6π-electrocyclization’ when the reaction was carried out at higher temperature. The regioselectivity of the Heck reaction of 2,3,6-tribromo-N-methylindoles was in favour of carbon atoms C-2 and C-3. The 1,2-dihydrocarbazoles were transformed, by Pd/C-catalyzed dehydrogenation, into the corresponding carbazoles in high yield. 相似文献
2.
Russian Chemical Bulletin - 2,3-Difluoronaphthalene (1) was selectively converted into 1-methyl-, 1,4-dimethyl-, 1-acetyl-, 1-acetyl-4-methyl-, 1-formyl-, and 1-carboxyl-substituted... 相似文献
3.
Synthesis of 2,6-diaryl-1,2-dihydropyridines through a 6π-electrocyclization of N-sulfonylazatrienes
The development of an efficient synthetic method toward substituted 1,2-dihydropyridines from cinnamylideneacetophenones is reported. The key intermediates N-sulfonylazatrienes were synthesized through a TiCl4-mediated direct condensation of primary sulfonamides with the substituted (E,E)-cinnamylideneacetophenones. The 6π-electrocyclization of these intermediates, catalyzed by a Lewis acid, selectively afforded the desired products in good yields. 相似文献
4.
3-Oxo-3-phenyl-2-(p-tolylhydrazono)propanal (1a) undergoes condensation with ethyl cyanoacetate in acetic acid in the presence of ammonium acetate to yield either 2-hydroxy-6-phenyl-5-p-tolylazonicotinic acid ethyl ester (6a) or 2-amino-6-phenyl-5-ptolyl-azonicotinic acid ethyl ester (8), depending on the reaction conditions. Similarly, other 3-oxo-3-aryl-2-arylhydrazonopropanals 1a,b condense with active methylene nitriles 2c,d to yield arylazonicotinates 6b,c. In contrast, 2-[(4-nitrophenyl)-hydrazono]-3-oxo-3-phenyl-propanal (1c) reacts with ethyl cyanoacetate to yield ethyl 6-(4-nitrophenyl)-2-oxo-2,6-dihydropyrido[3,2–c]cinnoline-3-carboxylate (11), via a novel 6π-electrocyclization pathway. Finally, 3-oxo-2-(phenylhydrazono)-3-p-tolylpropanal (1d) condenses with 2a-c to yield pyridazinones 13a-c. 相似文献
5.
The reaction of simple β-ketoesters and propargylamines under gold(III) catalysis leads to the formation of the elusive 2,5-dihydropyridine system. This new reaction provides the synthesis of potentially bioactive compounds in moderate to high yields. 相似文献
6.
Three approaches to the synthesis of β2-homophenylalanine derivatives using Negishi cross-coupling reaction are reported. In the first two approaches, two protected α-iodomethyl-β-amino esters are each converted into the corresponding organozinc iodides, which then undergo Pd-catalysed cross-coupling with aromatic halides to give β2-homophenylalanine derivatives, and the X-ray crystal structure of one product is reported. Alternatively, Negishi cross-coupling of the zinc reagent derived from N-benzyl 3-iodomethyl azetidin-2-one and aryl halides gave 3-benzylazetidin-2-ones, masked β2-homophenylalanine derivatives. The X-ray crystal structure of 1-benzyl-3-[(p-toluenesulfonyloxy)-methyl]-azetidin-2-one confirms the structural assignment. 相似文献
7.
The reactivity of a series of conformationally constrained bispropargyl sulfones with an ortho alkenyl moiety was studied. Under basic condition, these molecules underwent isomerization, first to monoallene followed by 6π-electrocyclization (6π-EC). Another cycle of isomerization and 6π-EC gave the bis naphthyl sulfones. No Garratt–Braverman (GB) Cyclization product could be isolated even on easing up the strain. Computations with DFT (at BP86-D3/def2-SVP level) indicated that, it is energetically more favorable for the initially formed monoallenic intermediate to undergo electrocyclization rather than isomerize to bisallene. This is in contrast to the acyclic unconstrained counterpart, where isomerization to bisallene is preferred and competing GBC/6π-EC of bisallenes results in mixture of products. 相似文献
8.
A. V. Aksenov I. V. Aksenova I. V. Borovlev A. A. Bumber A. F. Pozharskii Yu. I. Smushkevich 《Chemistry of Heterocyclic Compounds》1996,32(10):1196-1199
It has been shown that the reaction of 2, 3-biquinolyls with an excess of lithium in tetrahydrofuran leads to the formation of dianions, treatment of which with water or D2O gives 1, 4-dihydro-2, 3-biquinolyls or their 4-D derivatives in good yield. Oxidation of the latter leads to 4-D-2,3-biquinolyl. The reduction of 2, 3-biquinolyl has been studied.Stavropol State University, Stavropol 355009. Rostov State University, Rostov-on-Don 344090. Russian University of Chemical Technology, Moscow 125190. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1391–1394, October, 1996. Original article submitted September 10, 1996. 相似文献
9.
The palladium-catalyzed arylation of olefins (the Heck reaction) is one of the most versatile tools for C-C bond formation in organic synthesis. Phosphine ligands are generally used to stabilize the reactive palladium intermediates, the air-sensitivity of phosphine ligands, however, places significant limits on their synthetic applications. Recently, Yang1 and we2 have reported Heck and Suzuki reactions of highly active arenediazonium salts and halides catalyzed by air-stable monothiourea-Pd… 相似文献
10.
An expedient synthetic approach of naphthalenes was developed by the reaction of Morita-Baylis-Hillman bromides and arylacetylenes. The synthesis was carried out via a tandem copper-catalyzed alkynylation, propargyl-allenyl isomerization, and 6π-electrocyclization protocol. 相似文献
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13.
ZHANG Zhong-Biao HE Da-Yong CHI Guo-Chen CHEN Ru-YuState Key Laboratory of Elemento-Organic Chemistry Institute of Elemento-Organic Chemistry Nankai University Tianjin China 《中国化学》1997,15(6):548-552
A convenient procedure for the preparation of some new germasesquioxides containing phosphonyl groups carried by an intramolecular catalytic Mannich-type reaction is reported. 相似文献
14.
β-Alkoxyvinyl bromodifluoromethyl ketones 1a, 1b and 1c were synthesized by the reaction of bromodifluoroacetic anhydride with appropriate vinyl ethers in high yields. The acyclic enone 1a reacted with amines to give the corresponding β-aminovinyl bromodifluoromethyl ketones 2 in good yields. The reaction of 1a with electrophilic reagent ICl yielded α-iodoenone 4. The substitution reaction of the cyclic enones 1b and 1c with thio-nucleophiles gave the corresponding difluoromethylene thioethers 6. The three-component reactions of 2 with primary amines and formaldehyde gave multifunctional 1,2,3,4-tetrahydropyrimidine 3 in moderate yields. 相似文献
15.
N-((S)-1-Phenylethyl)halofluoroethanamides have been investigated as precursors to N-protected α-fluoro-α-amino amides by nucleophilic displacement of halide with nitrogen nucleophiles such as potassium phthalimide, sodium succinimide, sodium glutarimide, trimethylamine and sodium azide. With single diastereoisomers of the iodofluoroethanamide, clean inversion of configuration occurs at room temperature, but subsequent epimerisation may occur as a result of the liberated iodide. The α-fluoro-α-amino amides made underwent a wide variety of reactions depending on conditions, but in many cases the carbon-fluorine bond was compromised. However, reacting trimethylamine and N-((S)-1-phenylethyl)iodofluoroethanamide gave the corresponding α-fluorobetaine amide, and subsequent acidic hydrolysis led to α-fluorobetaine as the first example of an ‘unprotected’ α-fluoroamino acid. 相似文献
16.
A series of BiQuinazolinones bearing either double or triple bonds in their lateral chains have been synthesized. These compounds were then subjected to substrate-controlled reactions such as Diels-Alder, epoxidation and Pauson-Khand reactions. The stereoselective outcome observed in these transformations is very promising for the future application of BiQuinazolinones as chiral auxiliaries. 相似文献
17.
《Journal of organometallic chemistry》1986,316(3):271-279
1,1′-Diphenyl-3,3′,4,4′-tetramethyl-2,2′,5,5′-tetrahydro-2,2′-biphosphole obtained by reductive dimerization of the appropriate phosphole has been converted into the corresponding 2,2′-biphosphole by P-bromination followed by dehydrobromination of the resulting P,P′-tetrabromo compound with α-picoline. This 2,2′-biphosphole gives two isomeric P-sulfides upon reaction with sulfur, and a Mo(CO)4 chelate upon reaction with Mo(CO)6. Cleavage of the two P-phenyl bonds by lithium in THF yields the corresponding biphospholyl anion, which is converted into a mixture of two isomeric bis(η5,η5-2,2′-diphosphafulvalene)diirons by treatment with FeCl2. The reaction of Mn2(CO)10 in boiling xylene affords a mixture of three complexes, including a (η5,η5-2,2′-diphosphafulvalene)hexacarbonyldimanganese produced by thermal cleavage of the two PPh bonds. Under CO pressure there is a [1,5] P → C shift of the two phenyl groups, leading to formation of (η5,η5-3,3′-diphenyl-2,2′-diphosphafulvalene)hexacarbonyldimanganese. 相似文献
18.
A facile one-pot, multicomponent protocol for the synthesis of 1,4-dihydro-pyrano[2,3-c]pyrazole derivatives using a urea catalyst is reported. This transformation proceeds via a four-component reaction of ethyl acetoacetate, a hydrazine, 3-oxo-pentanedioic acid dimethyl ester, and malononitrile. The bifunctional nature of urea means that it catalyzes many steps in this transformation, including domino Knoevenagel condensation, Michael addition, and ring opening and closing reactions. This synthetic method has several advantages, including good yield, simple work-up, harmless by-products, and simple purification. 相似文献
19.
Novel β-aminocyclobutanecarboxylic acid derivatives were prepared via a sequential solvent-free aza-Michael addition of benzophenone imine across 3-halopropylidenemalonates and base-induced ring closure. These highly substituted cyclobutanedicarboxylic acid derivatives were subjected to a reactivity study which demonstrated the tendency of these donor-acceptor substituted four-membered rings to be converted into their corresponding ring-opened products. 相似文献
20.
The reactions of high-molecular-weight polydimethylsilane with metal chlorides in variable oxidation states at high temperature in the absence of a solvent afford mixtures of ,-dichloropermethyloligosilanes Cl(Me2Si)
m
Cl (m= 2—9). The influence of the reaction conditions (temperature, reaction time, and the reagent ratio) on the composition and yields of the reaction products was examined. 相似文献