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1.
Ratna Dasgupta Pranab R. Kanjilal Swapan K. Patra Manish Sarkar Usha Ranjan Ghatak 《Tetrahedron》1985,41(23):5619-5625
The efficacy of a new acid-catalyzed intramolecular C-alkylation has been demonstrated by the synthesis of 1-methyl-4--methoxyphenylbicyclo [2.2.2] octan-2-one () and 4--methoxyphenylbicyclo [2.2.2] octan-2-one () from easily accessible starting materials. The carbinol , derived from , undergoes facile rearrangement leading to 1--methoxyphenyl-4-methyl bicyclo [3.2.1] oct-3-ene (), which has been transformed to -1--methoxyphenyl-4-methylbicyclo [3.2.1] octan-3-one (). 相似文献
2.
2-(Trifluoromethyl)imidazo[4,5-] and -[4,5-]quinoline have been prepared from 5(6),acetamido-2-(trifluoromethyl)benzimidazole and 7,8-diaminoquinoline respectively. These (trifluoromethyl)- quinolines like 2-(trifluoromethyl)imidazoles but unlike 2-(trifluoromethyl) benzimidazoles, undergo hydrolysis in dilute sodium hydroxide to give ultimately the corresponding imidazo[4,5-] and -[4,5-]- quinoline, respectively. 相似文献
3.
Sanae Maruyama Yoshinori Fujimoto Masuo Morisaki Nobuo Ikekawa 《Tetrahedron letters》1982,23(16):1701-1704
[24-2H]-, [25-2H]-, and [23,23,25-2H3]-24ξ-methylcholesterol as well as [23,23,25-2H3]-24-methylenecholesterol were metabolized in the silkworm to cholesterol containing zero, one, three and three deuterim, respectively. 相似文献
4.
《Journal of fluorine chemistry》1987,36(3):283-291
Product patterns can be altered in reactions of -nitrobenzotrichloride [VI] with [AHF]x·NH4F complex. Side-chain fluorination predominates under ‘mild’ conditions. In contrast. ‘forcing’ conditions affected unexpected - fluorination-reduction to give -aminobenzotrifluoride [V] in high yield [75%] and purity [99.6%]. - reduction is probably initiated by a combination of iron from the stainless steel autoclave and trace amounts of moisture. The transformation of [VI] to [V] represents another type of - fluorination-reduction nitroaromatics, e.g. nitrobenzene [VII] to -fluoroaniline [VIII]. -Nitrobenzotrichloride [XI] degraded under ‘forcing’ conditions with [AHF]x·NH4F. 相似文献
5.
The synthesis of a PGH2 analog 5-(2(Z), 6-(1E)-3-diazo-5-(7-hydroxy-2-heptenyl)-6-(3-hydroxy-1-octenyl)bicyclo[2.2.1]heptan-2-one 2 is described. 相似文献
6.
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
7.
3-(t-Butoxycarbonyl)-2-(trifluoromethyl)imidazo[1,2-]-pyridine, prepared from trifluoroacetonitrile and pyridinium t-butoxycarbonylmethylide, reacts smoothly with trifluoroacetic acid to provide 2-(trifluoromethyl)imidazo[1,2-]pyridine-3-carboxylic acid, which gives 2-(trifluoromethyl)imidazo[1,2-]-pyridine when heated. 3-Cyano-2-(trifluoromethyl)imidazo[1,2-]pyridine can be obtained treatment of trifluoroacetonitrile with pyridinium cyanomethylide, which is sufficiently reactive to effect nucleophilic displacement of fluorine from pentafluoropyridine under mild conditions [→pyridinium cyano(tetrafluoro-4-pyridyl)methylide]. 相似文献
8.
Claudio Fuganti Piero Grasselli Giuseppe Pedrocchi-Fantoni 《Tetrahedron letters》1979,20(26):2453-2454
Feeding experiments with (4) [5-3H;5-14C]-leucine () and with the (4) [5-3H;2-14C]-isomer () show that incorporation into the isoprenylated tryptophan derivative echinuline (), produced by , involves, to a large extent, loss of the fragment enbodying the carbon atom at position 2 of the fed amino acid. 相似文献
9.
As synthetic precursors of hexaaza-kekulene 1 the dibenzo[]= [1,10] phenanthroline systems 2, 3, 4, 5 and 6 were prepared. From 6 via 7 a product was obtained for which the dodecahydrohexaaza-kekulene structure 8 is suggested on the basis of 1H-NMR comparison with the dipyrido[3,2-;=2′,3′-]acridine (14) for which two syntheses are reported. 相似文献
10.
1,2-Dichloroethylene undergoes a stereospecific photoreaction with benzonitrile, the three tolunitriles, α,α,α-trifluorotoluene, fluorobenzene, and chlorobenzene to give substituted 6- 7- dichlorotricyclo[3,3,0,02,8]oct-3-enes which on treatment with base yield cyclised products or semibullvalenes: phenol yields dichlorobicyclo[3.2.1]oct-2-en-8-one with this ethylene photochemically. 相似文献
11.
Thomas J. Simpson 《Tetrahedron letters》1981,22(38):3785-3788
Incorporations of [1-13C]?, [2-13C]?, [1,2-13C2]-acetates and [13C]-methionine into anditomin, a metabolite of , indicate its formation by a mixed polyketide-terpenoid biosynthetic pathway similar to that elucidated for andibenin; observations are made on the possible biosynthetic relationship of the metabolites with austin and terretonin, mycotoxins recently isolated from and respectively. 相似文献
12.
13.
The synthesis of 7-(β--ribofuranosyl)-4-amino-5H-pyrrolo[3,2-]pyrimidine (9-deazaadenosine) is described. It involves base-catalyzed cyclization of N-carboethoxyenamine to give β- and α-ribosylated 3-amino-2-cyanopyrroles and , respectively, followed by a one-step conversion to the desired pyrrolo[3,2-]pyrimidine system. 相似文献
14.
1,2,3,4,7,7-Hexafluorobicyclo[2,2,1]hepta-2,5-diene gave 1,2,3,4-tetrafluorebenzene in at least 73% yield when heated to 450°C in a sealed tube; the CF2 bridge appeared, in part, as octafluorocyclobutane. Nucleophilic attack by sodium methoxide- methanol on the diene occurred exclusively at the CFCF bond, causing the formation of 1,2,4,7,7-pentafluoro-3-methoxybicyclo- [2,2,1]hepta-2,5-diene and a 1,4,5,6,7,7-hexafluoro-5-methoxybicyclo [2,2,1]hept-2-ene thought, on the basis of 19F nmr data, to be the 6--F,5--MeO isomer. Radical attack on 1,2,3,- 4,7,7-hexafluorobicyclo[2,2,1]hepta-2,5-diene by bistrifluoromethyl nitroxide took place at both olefinic sites, with a . 10:1 preference for the CFCF linkage; all three geometrical isomers of 5,6-bis(bistrifluoromethylamino-oxy)-1,4,5,6,7,7- hexafluorobicyclo[2,2,1]hept-2-ene were formed. 相似文献
15.
The 6-phenyl-dihydro-α-pyrone moiety of psilotin is formed from [2′,3′-13C2,1′-14C,-4-3H]phenylalanine in the plant with retention of all the isotopes. 相似文献
16.
- and -2-Methylamino and 2-benzylamino-3-hydroxymethylbicyclo [2.2.1]heptanes and the corresponding bicycio [2.2.1] heptenes ( -, -) were synthesized from β-amino acid esters containing the norbornane or norbornene skeleton (-). The aminoalcohols were converted to 5,8- methano -3,1-benzoxazines by reaction with formaldehyde. As established by 1H and 13C NMR spectroscopy, the predominant conformation is () for the , and () for the derivatives. 相似文献
17.
S-Alkylation of 1,2,4-triazine-6-thiones with 4-iodobutyne, followed by oxidation to the sulfoxide and intramolecular cycloaddition (at room temperature),gives 2,3-dihydrothieno[2,3-]pyridines, which are readily dehydrated with acetic anhydride to thieno[2,3-]pyridines. The same series of reactions carried out on 1,2,4-triazine-3-thiones leads to thieno[2,3-]pyridines. 相似文献
18.
Two novel nucleosides, mycalisines A and B, have been isolated from a marine sponge and their structures elucidated as 4-amino-5-cyano-7-(3--methyl-5-deoxy-β-D--pent-4-enofuranosyl)-pyrrolo[2,3-]pyrimidine and 5-cyano-7-(3--methyl-5-deoxy-β-D--pent-4-enofuranosyl)-pyrrolo[2,3-]pyrimidine-4-one, respectively. Both compounds inhibit cell division of fertilized starfish eggs. 相似文献
19.
The 1H and 13C nmr spectra of , -9-oxobicyclo[3.3.1]nonane-2,4-dicarboxylic acid, 3, in DMSO-d6 or alkaline D2O, clearly show that it exists in a --conformation with carboxyl groups, thus being the first case of - preference of a bicyclo[3.3.1] nonan-9-one due to the presence of ,-2,4- substituents. 相似文献
20.
The hydrogenation of -6-methylenebicyclo[2,2,2]octan-2-ol catalysed by a range of rhodium and iridium complexes has been investigated. Unlike the corresponding -alcohol, reduction is highly stereoselective leading to 95 – 99.7% of -exo-6-methylbicyclo[2,2,2]octan-2-ol. Selectivity is much less pronounced for the corresponding methyl ether. Rhodium catalysts promote a competitive isomerisation of the double bond to -6-methyl-bicyclo[2,2,2]oct-5-en-2-ol, of which an authentic sample was reduced in high yield to pure - product. Reduction of both -hydroxy substrates by iridium complexes is rapid and highly selective.NMR studies employing europium shift reagents played a central part in defining the stereochemical interrelationships of 2,6-disubstituted bicyclo[2,2,2]octanes. 相似文献