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1.
[reaction: see text]. Tetramethoxy-p-tert-butylcalix[4]arene reacts readily with n-butyllithium to give a putative monolithiated intermediate that is substituted with alkyl halides and carbon dioxide to give in 60-75% yield conformationally mobile calix[4]arenes monosubstituted at the methylene bridge (2-position). 2-Alkyl- and 2-benzyl-substituted tetramethoxycalix[4]arenes are converted in 62-68% overall yield to the corresponding tetrahydroxy-p-tert-butylcalix[4]arenes by treatment with boron tribromide. The tetrahydroxy-p-tert-butylcalix[4]arenes exist in the cone conformation at room temperature in CDCl3 as judged by NMR spectroscopy. 相似文献
2.
[reaction: see text] The first example of palladium-catalyzed cycloisomerization of (Z)-2-en-4-yne-1-thiols 1 to give substituted thiophenes 2 is reported. Cycloisomerization reactions are carried out under nitrogen at 25-100 degrees C in N,N-dimethylacetamide as the solvent in the presence of catalytic amounts of PdI2 in conjunction with KI to give the corresponding thiophenes in 43-94% yield. 相似文献
3.
The three-component reactions (TCRs) involving quinoline or isoquinoline, dialkyl acetylenedicarboxylate and β-trifluoroacetyl vinyl ethyl ether were investigated. The reaction proceeded smoothly under ambient temperature in DMSO to give the 4-trifluoroacetyl substituted benzo[c]quinolizine derivatives in moderate yields. However, under the same reaction condition, isoquinoline afforded the 2-trifluoromethyl substituted 1-oxa-(11H)-benzo[a]dihydroquinolizine or 4-trifluoroacetyl substituted benzo[a]dihydroquinolizine products. The possible reaction pathways were proposed. 相似文献
4.
Brian H. KirkDaniel H. Ess 《Tetrahedron letters》2011,52(12):1245-1249
The Diels-Alder reaction of substituted cyclohexadienes with substituted phenylacetylenes offers an attractive alternative for the synthesis of biaryl compounds via a two-step cycloaddition/cycloelimination pathway. Quantum mechanical calculations using B3LYP and M06-2X density functional methods for the reaction of 2-chloro-6-nitrophenylacetylene with 1-carbomethoxy-cyclohexadiene show the reaction proceeds by a stepwise diradical [4+2] cycloaddition followed by concerted [2+4] cycloelimination of ethylene. [2+2] cycloadducts are also the result of stepwise addition. [2+2] cycloadducts isomerize to [4+2] cycloadducts via diradical pathways, which involve the same diradical intermediate in cycloaddition. There is also a competitive conrotatory ring opening followed by trans-cis double bond isomerization pathway of the [4.2.0] bicycle (the [2+2] cycloadduct) to give the cis,cis,cis-1,3,5-cyclooctatriene. 相似文献
5.
Mohamed M. El-Kerdawy Said M. Bayomi Ihsan A. Shehata Richard A. Glennon 《Journal of heterocyclic chemistry》1987,24(2):501-504
A convenient route is reported for the synthesis of substituted 1,3,4-thiadiazolo[3,2-a]-1,3,5-triazine-5,7-diones and isoxazolo[2,3-a]-1,3,5-triazines. Condensation of the appropriately substituted 2-amino-1,3,4-thiadiazole and 3-aminoisoxazole with phenoxycarbonyl isocyanate provides the desired target compounds in fair yield. 相似文献
6.
Acylation of substituted 4-(furyl-2)-4-arylaminobut-1-enes with maleic anhydride provided 2-allyl-6-carboxy-4-oxo-3-aza-10-oxatricyclo[5.2.1.01,5]dec-8-enes in high yield under mild reaction conditions. The Diels-Alder adducts are formed via an initial amide formation followed by a stereoselective intramolecular [4+2] exo-cycloaddition reaction. Treatment of the tricyclic compounds with phosphoric acid at high temperatures (70-120 °C) promoted cyclic ether opening, intramolecular cyclization and aromatization to give the corresponding tetracyclic compounds, 5,6,6a,11-tetrahydro-10-carboxyisoindolo[2,1-a]quinolines, in moderate yields. The influence of the acid and the reaction temperature on the cyclization reactions are also discussed. 相似文献
7.
Wu CY Lin YC Chou PT Wang Y Liu YH 《Dalton transactions (Cambridge, England : 2003)》2011,40(14):3748-3753
Intermolecular [2+2+2] cycloaddition reaction employing an air-stable ruthenium perchloro-cyclobutenonyl complex as a catalyst is reported. A series of internal alkynes were incorporated with dimethyl acetylene-dicarboxylate in a ratio of 1:2 to give various substituted benzenes in high yield and high chemoselectivity. 相似文献
8.
G. G. Danagulyan L. G. Sahakyan G. A. Panosyan 《Chemistry of Heterocyclic Compounds》2000,36(2):185-189
The condensation of substituted 2-benzyl-4-hydrazinopyrimidines with phenylpyruvic acid gave the corresponding hydrazones, which cyclize upon the action of POCl, to give derivatives of pyrimido[6,1-c][1,2,4]-triazine. The substituted 2-benzylpyrimidinylhydrazides of some carboxylic acids react with POCl, to give 1,2,4-triazolo[4,3-c]pyrimidines. The reaction of 7-benzyl-5-methyl-l-phenyl-1,2,4-triazolo[2,3-c]pyrimidine with sodium ethylate leads to rearrangement and formation of 7-benzyl-5-methyl-2-phenyl-1,2,4-triazolo[2,3-c]pyrimidine.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 225–229, February, 2000. 相似文献
9.
An efficient method for the cocyclotrimerization of bicyclic alkenes and benzynes catalyzed by palladium phosphine complexes to give the corresponding norbornane anellated 9,10-dihydrophenanthrene derivatives is described. Bicyclic alkenes 1a-i undergo [2 + 2 + 2] cocyclotrimerization with benzynes generated from precursors 2a-d [2-(trimethylsilyl)phenyl triflate (2a), 4,5-dimethyl-2-(trimethylsilyl)phenyl triflate (2b), 6-(trimethylsilyl)-2,3-dihydro-1H-5-indenyl triflate (2c), 4-methyl-2-(trimethylsilyl)phenyl triflate (2d)] in the presence of PdCl(2)(PPh(3))(2) in acetonitrile at ambient temperature to yield anellated 9,10-dihydrophenanthrene products 3a-r in moderate to excellent yields. The [2 + 2 + 2] cocyclotrimerization products from oxa- and azabicyclic alkenes can be applied for the synthesis of polyaromatics, substituted benzo[b]triphenylenes (8a-f), via a simple Lewis acid mediated deoxyaromatization in good yields. In addition the [2 + 2 + 2] products undergo retro Diels-Alder reaction readily, providing a new method for the synthesis of substituted phenanthrenes and for generating isobenzofurans. A plausible mechanism is proposed to account for the catalytic [2 + 2 + 2] cycloaddition reaction. 相似文献
10.
The carbonylation of a phenyllithium containing an oxazoline group at the ortho position, followed by quenching with water, afforded a tricyclic compound, 3,3-dimethyl-2,3-dihydrooxazolo[2, 3-a]isoindol-5(9bH)-one, in 91% yield. This reaction proceeded via an intramolecular cyclization of the aroyllithium species, to give the tricyclic dienolate. Treatment of the tricyclic dienolate with electrophiles, such as alkyl halides, aldehydes, ketones, and epoxides gave the substituted oxazolo[2,3-a]isoindolinones in good yield. 相似文献
11.
[reaction: see text] Densely substituted styryl sulfone 20 is shown to undergo double annulation with phthalide 21 to give, in one-pot operation and in excellent yield, the benzonaphthopyranone scaffold 22 of gilvocarcins. 相似文献
12.
《Tetrahedron letters》1986,27(11):1281-1284
Ethyl cyclopropylidene acetate and analoges are prepared in good yield by an acid catalyzed Wittig reaction. They are used as equivalents of senecioic acid esters in the aprotic double Michael reaction to give spirocyclopropyl substituted bicyclo[2.2.2] octanes. 相似文献
13.
Buta-2,3-dienoate reacts with vinyl ketenimine to give the corresponding substituted aniline through a Diels-Alder cycloaddition. Besides the expected Diels-Alder adduct 3a, the aniline 3b was also obtained in a ratio of 91:9. The observed (13)C exchange is explained on the basis of a reversible [2 + 2] cycloaddition competing with the [4 + 2] process. This is supported by B3LYP DFT computations, as a stepwise pathway lies very close in energy to the [4 + 2] concerted one. [reaction: see text] 相似文献
14.
George Bosah Okide 《Journal of heterocyclic chemistry》1992,29(6):1551-1555
1-Chloro-1,3-bis(dimethylamino)-3-phenyl-2-azaprop-2-en-1-ylium perchlorate obtained from the reaction of phosphorus oxychloride-N,N-dimethylbenzamide complex and dimethylcyanamide reacts with 2-amino-4-methylpyridine to yield 8-methyl-4-dimethylamino-2-phenylpyrido[1,2-a]-1,3,5-triazinium perchlorate ( 8 ). The structure is established by X-ray crystallography. Various suitably substituted pyridines react similarly to afford the corresponding pyrido[1,2-a]-1,3,5-triazinium salts. The intermediates obtained from several secondary amides give identical products when treated with the same pyridines. The limitations of this procedure are investigated. 相似文献
15.
[Chemical reaction: See text] Starting from methyl 5-oxo-6-trifluoromethanesulfonyloxy-1,2,3,5-tetrahydroindolizine-8-carboxylate, obtained by a Rh(II)-catalyzed 1,3-dipolar cycloaddition reaction of 1-(2-benzenesulfonyl-2-diazoacetyl)pyrrolidin-2-one and methyl acrylate, several indolo- and furano-fused indolizinones were efficiently prepared. In the first case, a palladium-mediated C-N coupling of the triflate with a variety of substituted anilines provided the desired methyl 5-oxo-6-(arylamino)-1,2,3,5-tetrahydroindolizine-8-carboxylates in high yield. Methyl 6-(2-bromophenylamino)-5-oxo-1,2,3,5-tetrahydroindolizine-8-carboxylate as well as its decarboxylated analogue, 6-(2-bromophenylamino)-2,3-dihydro-1H-indolizin-5-one, were synthesized in excellent yield and were found to undergo an intramolecular Heck cyclization to give 1,2,3,6-tetrahydroindolizino[6,7-b]indol-5-ones. To prepare furano-fused indolizinones, methyl 6-hydroxy-5-oxo-1,2,3,5-tetrahydroindolizine-8-carboxylate was etherified with different allyl halides, and the resultant allyl ethers were subjected to a thermal Claisen rearrangement to give the corresponding methyl 7-allyl-6-hydroxy-5-oxo-1,2,3,4-tetrahydroindolizine-8-carboxylates. Cyclization under Wacker oxidation conditions afforded methyl 2-methyl-8-oxo-5,6,7,8-tetrahydro-1-oxa-7a-aza-s-indacene-4-carboxylates in near-quantitative yield. 相似文献
16.
[reaction: see text] A new synthetic route to 2-aryl-N-tosyl azetidines has been developed starting from N-tosylarylaldimines in two steps in an overall yield of 63-70%. A formal [4 + 2] cycloaddition of these 2-aryl-N-tosylazetidines with nitriles in the presence of BF3.OEt2 has been described for the synthesis of substituted tetrahydropyrimidines. It is proposed that the reaction proceeds in Ritter fashion. 相似文献
17.
An efficient two-step method was described for the synthesis of chromeno[3',4':5,6]pyrano[2,3-b]indole derivatives. The three-component reaction of 4-hydroxycoumarin, variously substituted benzaldehydes and indolin-2-one was promoted by P2O5 in refluxing ethanol to give trimolecular adducts, which were then cyclized in 1,2-dichloroethane under reflux using POCl3. 相似文献
18.
H. M. Moustafa 《Phosphorus, sulfur, and silicon and the related elements》2013,188(7):1397-1412
2,4-Bis(4-methoxyphenyl)-1,3,2,4-dithiadiphosphetane-2,4-disulfide (Lawesson's Reagent, LR, 1 ) reacts with cycloalkylidenecyanothioacetamides ( 2 and 3 ) to give 5'-cyano-2'-(4-methoxyphenyl)spiro [cyclopentane(cyclohexane)-1,6'-perhydro-[1,3,2]thiazaphosphixane]-2',4'-disulfide ( 4 and 5 ). The reaction of compounds 4 and 5 with f -halo compounds led to the formation of the substituted thio-compounds 6a-e and 7a-e , respectively, these compounds, upon treatment with sodium ethoxide, produce the corresponding thienothiazaphosphixine derivatives 8a-e and 9a-e respectively. Compounds 8a-e and 9a-e react with LR under different reaction conditions to give polyfused heterocyclic compounds 10a-d and 11a-d respectively. Treatment of compounds 8b and 9b with CS 2 and (CH 3 ) 2 SO 4 gave the corresponding dithiocarbamate methyl ester derivatives 12 and 13 , respectively, which on treating with hydrazine hydrate yielded compounds 14 and 15 respectively. Compounds 14 and 15 reacted with LR to yield compounds 16a , b and 17a , b respectively. 相似文献
19.
20.
Martine Croisy-Delcey Emile Bisagni Christiane Huel 《Journal of heterocyclic chemistry》1993,30(1):55-60
4-Chloroquinoline-5,8-dione ( 8a ) and 6-bromo-4-chloroquinoline-5,8-dione ( 8b ) were reacted with homophthalic anhydride to give tetracyclic compounds 10 and 11 respectively. The 6,11-dihydroxy derivative 12 was prepared in low yield by photochemical addition of benzocyclobutenedione to 4-chloroquinoline-5,8-dione ( 8a ) and in better yield through a Friedel-Crafts reaction of phthalic anhydride with 4-chloro-5,8-dimethoxyquinoline ( 7a ). Whereas 4-chloro-6-hydroxynaphtho[2,3-g]quinoline-5,12-dione ( 11 ) was substituted by amines in the usual way to the corresponding 4-amino-substituted derivatives, 4-chloro-11-hydroxynaph-tho[2,3-g]quinoline-5,12-dione ( 10 ) led to a mixture of 4-amino derivatives and the unexpected 2,6-disubstituted-imidazo[4,5,l-I-j]naphtho[2,3-g]quinolin-7-ones, 13a-b . 相似文献