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1.
The reaction of phenyl lithium acetylide () with 2,6-diphenylpyrylium perchlorate () is solvent dependent. With diethyl ether as solvent, the isolated product differed from that previously reported and is reassingned as 2,6-diphenyl-4-phenylacetylenyl-4-pyran (). On the other hand, in THF the title compound () was obtained; its structure confirmed by single-crystal x-ray crystallography. 相似文献
2.
Gurjeet S. Phull Raymond G. Plevey John Colin Tatlow 《Journal of fluorine chemistry》1984,25(2):111-122
The nitro-group survived in the fluorination of pentafluoronitrobenzene by cobalt(III) fluoride at 135–150°, the major products being undecafluoronitrocyclohexane and nonafluoro-4-nitrocyclohex-1-ene. 2H- Tetrafluoronitrobenzene similarly afforded and -2H-1-nitrodeca- fluorocyclohexane and 5H/4-nitro-octafluorocyclohex-l-ene. Pentafluoro- benzaldehyde was fluorinated to give undecafluorocyclohexanecarbonyl fluoride and nonafluorocyclohex-3-enecarbonyl fluoride. Nonafluoro-4- nitrocyclohex-1-ene was oxidized to 3-nitroheptafluorohexan-1,6-dioic acid, and undecafluoronitrocyclohexane was hydrogenated over a palladium catalyst at low pressure to give decafluorocyclohexanone oxime and 1H-decafluoro- cyclohexanamine, accompanied by 1-aminononafluorocyclohex-1-ene. 相似文献
3.
A facile 1,5-migration of a -butyldimethylsilyl group and a new cleavage reaction of -butyldimethylsilyl ether to alcohol in prostaglandin intermediates are described. 相似文献
4.
Cycloaddition reactions between vinyl ethers 3 and -quinone methides 2, thermally generated from 2-hydroxybenzyl alcohols 1, have been studied. The structure and conformational preferences of the 4-substituted 2-ethoxy-(2,3)-dihydro-2-benzopyrans 4–9 obtained, which show new interesting features, are discussed together with competitive kinetic data. The cycloaddition process is concerted and involves -quinone methides in the -configuration. The OEt- transition state seems to be preferred with ethyl vinyl ether and -1-propenyl ethyl ether, whereas with -1-propenyl ethyl ether the stereoselectivity of the cycloaddition process depends on substituents on the methylene group of the starting alcohol 1. These results are discussed in terms of and preference of the propenyl ether methyl group. 相似文献
5.
Takehiko Nishio Katsuhiro Katahira Akira Kato Choji Kashima Yoshimori Omote 《Tetrahedron letters》1979,20(43):4211-4212
Irradiation of N-aryl-2(1H)-pyrimidin-2-ones (-) in a mixed benzene-alcohol solution afforded the products initiated by Type I cleavage, 1-(3-alkoxycarbonylamino-2-propene)-N-arylimines (-, , and ) in 45–51% yields. 相似文献
6.
A 4′-ene derivative of kanamycin B () was derived from the epoxide () by oxidative elimination of the 4′-phenylseleno group into the allylic alcohol (). The title compound, 0-(2,6-diamino-2,4,6-trideoxy-β-L-arabino-hexopyranosyl)-(1→4)-0-[3-amino-3-deoxy-α-D-glucopyranosyl-(1→6)]-2-deoxystreptamine () was obtained from by stereospecific hydrogenation followed by removal of the masking groups, changing the D-sugar moiety of the 4-0-glycoside portion into an L-sugar. 相似文献
7.
(1,5)-(-)-Karahana ether (8,8-dimethyl-2-methylene-6-oxabi-cyclo[ 3.2.1]octane) and (1,5)-(-)-karahana lactone (8,8-dimethyl-2-methylene-6-oxabicyclo [3.2.1]octan-7-one) were synthesized from ()-3-hydroxy-2,2-dimethylcyclo-hexanone. The natural karahana lactone was shown to be almost racemic (. 1.3 % e.e.). 相似文献
8.
Wojciech Dmowski 《Journal of fluorine chemistry》1980,15(4):299-313
Unlike unsubstituted perfluoropropene [1,2] 1-(2-tetrahydrofuryl)-pentafluoropropene reacts with sodium alkoxides in parent alcohol solutions to give 1-alkoxy-1-(2-tetrahydrofuryl)-tetrafluoropropenes as major products and 1-alkoxy-2H-1-(2-tetrahydrofuryl)-pentafluoropropanes as very minor products. The yield of adducts is, to some extent, increased by the reduced basicity of the alkoxide ion. Results are discussed in terms of the supposed properties of the carbanionic intermediates involved.N.m.r., m.s., and i.r. data for, and some chemical properties of compounds , viz., further reactions with sodium alkoxides and hydrolysis are described. 相似文献
9.
4-(N-Alkylimino)methyl-2,6-di--butylphenols (), Schiff bases of 3,5-di--butyl-4-hydroxybenzaldehyde can be oxygenated in the presence of Co(Salpr), a five coordinate Co(II)-Schiff base complex to give N-alkyl-3--butyl-5-formyl-2-hydroxy-2-pivaloyl-1,2-dihydropyridines ( as the main product together with 3-formyl-2,5-di--butyl-2,4-cyclopentadienone () and 2,6-di--butyl-4-formyl-6-hydroxy-4,5-epoxy-2-cyclohexenone (). These products result from dioxygen incorporation into the ortho position of . 相似文献
10.
1,3,7,9,11,12,14-Heptazapentacene-2,4,8,10 (14,3,9,12)-tetraones (mixed flavins) were prepared by the cyclization of 1,5-dihydro-8-[N-alkyl-N-(5-nitrouracil-6-yl)-amino-5-deazaflavins with Vilsmeier reagent. The mixed flavins oxidized alcohol under neutral condition in sunlight and a remarkable autorecycling was observed. 相似文献
11.
4-O-(2,6-diamino-2,3,4,6-tetradeoxy-3-C-methyl-β-L-arabino and lyxo-hexopyranosyl) and 4-O-(2-amino2,3,4,6-tetradeoxy-5-c-methyl-L-threo-hexopyranosyl-6-O-(3-amino-3-decxy-α-D-glucopyranosyl)-2-deoxystreptamine (, and ) were synthesized from a kanamycin B derivative () by regiospecific methylation and stereospecific hydrogenation followed by removal of masking groups, converting a D-sugar moiety (4-O-glycoside portion) into L-sugar. The usual conformation of and were determined as boat and skew by 250 MHz PMR spectra respectively. 相似文献
12.
E.G. Frandsen 《Tetrahedron》1977,33(8):869-873
The reaction of 4- and 5-aryl-3-methylthio-1,2-dithiolylium iodides with 4-hydroxy-6-methyl-2-pyran-2-one and 4-hydroxycoumarin has been studied. 4-Substituted salts yielded 3-aryl-7-methyl-2-thioxo-2,5-pyrano [3,2-c]pyran-5-ones and 3-aryl-2-thioxo-2H,5H-pyrano[3,2-c]benzo[e]pyran-5-ones, respectively, whereas 5-substituted salts gave rise to 3-(5′-aryl-1′,2′-dithiol-3′-ylidene)-6-methyl-2-pyran-2,4-diones and 3-(5′-aryl-1′,2′-dithiol-3′-ylidene)-2-benzo [b]-pyran-2,4-diones. 相似文献
13.
P. Molina A. Tárraga M.Lorenzo Peña E. Hurtado M.J. Vilaplana 《Tetrahedron letters》1982,23(29):2985-2986
A number of derivatives of the bicyclic 1,2,4-triazolo [1,5-a] pyridine () and pyrido [2,1-f][1,2,4] triazine ( and ) have been prepared by reaction of 2-methylthio- and 2-ethoricarbonyl-4, 6-diphenylpyrylium salts, respectively, with amidrazones. 相似文献
14.
The reactions of -2-methyl-2-pentene with activated methylene compounds such as acetylacetone, ethyl acetoacetate, benzoylacetonitrile, and benzoylmethyl perfluoroalkyl ketones in the presence of potassium fluoride were carried out. Each reaction proceeded smoothly in acetonitrile at room temperature by using ‘freeze-dried’ potassium fluoride as a condensing agent. Acetylacetone and ethyl acetoacetate gave both divinyl ether and pyran compounds, whereas other activated methylene compounds afforded only pyrans in good yields. 相似文献
15.
2,4,6-Triphenylpyrylium with thiosemicarbazide and thiocarbohydrazide, gives 2-pyrazolines and which undergo cyclization yielding pyrazolo(1,5-c]pyrimidine 5 and pyrazolo [2,3-d]-1,2,4-triazepine derivatives, respectively. Reaction of with phenacyl bromides gave 1,3-thiazolo[3,2-b]pyrazolo [2,3-d]-1,2,4-triazepin-4-iums . Compound on treatment with phenacyl bromides gave 1-(4'-aryl-thiazol-2'-yl)-2-pyrazoline derivatives . Compound reacts with acyl chlorides to give pyrazolo[1,5-c]pyrimidine derivatives , and with aromatic aldehydes giving the 2-(Δ2'1 pyrazolin-1-yl)-5-aryl-1,3,4-Δ2-thiadiazolines which were easily converted to the corresponding 2-(Δ2-pyrazolin-1-yl)-5-aryl-1,3,4-thiadiazoles . 相似文献
16.
The - and -2-amino-4-cyclohexene-1-carboxylic acids and react with imidates to give the condensed-skeleton, bicyclic - and -pyrimidin-4-ones and . The amino acids and were reduced to the -and -1, 3-aminoalcohoIs and , which were cyclized by means of imidates to the bicyclic tetrahydro-4-3,1-benzoxazines and , or were converted, the corresponding carbamates and into the tetrahydro-4-3,1-benzoxazin-2(1)-ones and . The 2-thioxo analogues and were prepared by cyclization of the dithiocarbamates obtained from the aminoalcohols and by treatment with carbon disulphide. The -aminoalcohol and its saturated analogue reacted with -chlorobenzaldehyde to furnish the hexahydro and octahydro-4-3,1-benzoxazine , respectively. 1H and 13C NMR studies showed that, similarly to the earlier-investigated analogues containing oxygen or unsubstituted nitrogen at position 1, the synthesized isomrs , , and occurred as the preferred conformer in the heterocyclic twist inverse form of -inside type ( C6-N bond) (B). In the isomers containing a saturated C-2 atom ( and ), H-2 and H-6 are in relative positions. 相似文献
17.
3H-1,2-Diazepines () give dinuclear complexes () on reaction with diiron nonacarbonyl. Complexation much reduces the rate of the [1,5] sigmatropic hydrogen shift across the diazepine ring and also reduces the activation energy for ring inversion. 相似文献
18.
The two C6, C7 substituted title compounds have been synthesized via stereoselective 5--Trig ringclosures starting from (E)-resp. (Z)-4-nonene-1-yl bromide and 3,5-morpholinedione. 相似文献
19.
Horst Prinzbach Klaus-Helmut Müller Clemens Kaiser Dieter Hunkler 《Tetrahedron letters》1980,21(36):3475-3478
-Dioxa,aza-tris-(8) and -oxa, aza-bis-σ-homobenzenes (21) have been synthesised. With activation barriers, which clearly support the concerted mechanism, they undergo [2+2+2]-cycloreversion yielding 7H-1,4,7-dioxazonines (9) and 4H-1,4-oxazocines (22), resp. 相似文献
20.
《Comptes Rendus Chimie》2002,5(6-7):517-523
Condensation of 4-hydroxy-6-methyl pyran-2-one 2 with 3-amino-1,2,4-triazole 1 in refluxing alcohol afforded 5-alkoxycarbonylmethyl-7-methyl-1,2,4-triazolo〚1,5-a〛pyrimidines and their isomers 5-alkoxycarbonylmethyl-7-methyl-1,2,4-triazolo〚4,3,-a〛pyrimidines 4. Reaction of hydrazine hydrate with compounds 4 and 5 yielded the corresponding hydrazid acids 6 and 7. Condensation of o-phenylenediamines 8 with esters 3(4) in refluxing xylol or with hydrazid acid 6(7) by melting reagents afforded 7(5)-〚benzimidazol-2-yl〛methyl-5(7)methyl-1,2,4-triazolo〚1,5-a〛(〚4,3-a〛)pyrimidines 9(10). The structures of the annealed compounds have been elucidated by their 1H, 13C NMR and Mass Spectroscopy data. 相似文献