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1.
Ammonia-promoted fragmentation of 2-alkyl- and 2,4-dialkyl-3-iodo-1- oxocyclohexan-2,4-carbolactones
2-Alkyl- and 2,4-dialkyl-3-iodo-1-oxocyclohexan-2,4-carbolactones undergo ammonia-promoted fragmentation reactions to provide butenolides, gamma-butyrolactone, and/or beta,gamma-epoxycyclohexanones. Product distribution is governed by the relative size of the substituents at C-2 and C-4 of the cyclohexanones. Butenolide amide, the major product from the fragmentation, is further converted into their respective piperidinone and pyrrolidine derivatives. 相似文献
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Jun-ichi Matsuo Mizuki Kawano Kosuke Takeuchi Hiroyuki Tanaka Hiroyuki Ishibashi 《Tetrahedron letters》2009,50(17):1917-1919
Fragmentation of (2S,3S,4S)-2-allyl-3-iodo-1-oxocyclohexan-2,4-carbolactone to (4S)-2-allyl-4-hydroxycyclohex-2-en-1-one, a chiral building block of (−)-platensimycin, proceeded efficiently by using scandium(III) triflate in DMF-H2O (1:3) at 100 °C. 相似文献
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Björn Ringdahl 《Tetrahedron》1979,35(20):2413-2418
The sign of the Cotton effects near 320 and 400 nm in the CD spectra of the N-2,4-dinitrophenyl derivatives of chiral 1-alkyl-2-propynylamines and 1-alkyl-2-propenylamines correlates with their absolute configurations. The Cotton effects are generated by the coupled oscillator methanism and their sign is the same as the chirality (right-handed screw for positive chirality) of the interaction of the dominant oscillators of the 2,4-dinitrophenylamino chromophore with that of the amine moiety, the chirality of the interaction being deduced by conformational analysis. 相似文献
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Antonio SalgadoYves Dejaegher Guido VerniestMark Boeykens Christine GauthierChristelle Lopin Kourosch Abbaspour TehraniNorbert De Kimpe 《Tetrahedron》2003,59(13):2231-2239
Several 1-alkyl-2-methylazetidin-3-ones were prepared in good yield by the hydride-induced cyclization of the corresponding β-bromo-α,α-dimethoxyketimines, the resulting 3,3-dimethoxyazetidines being hydrolyzed by acid. Imination of these 1,2-disubstituted azetidin-3-ones, followed by alkylation under kinetic control conditions resulted in regioisomeric mixtures of 2,4- and 2,2-dialkylated compounds. Analytical samples of the major 2,4-disubstituted derivatives were obtained after extensive chromatographic separation. The cis stereochemistry of the major 2,4-dialkylated isomer was demonstrated on the basis of NMR data. 相似文献
6.
Bao J Baker RK Doss GA Kayser F Kotliar A Miao S Parsons WH Rupprecht KM 《Organic letters》2002,4(11):1871-1873
[reaction: see text] Pentacyclic triterpenoid natural product correolide (1) was converted to ketone 2 via ozonolysis. An unusual fragmentation reaction of ketone 2 with LiCl was discovered. This reaction is general among several similar substrates examined and appears to be specific for the correolide-type E-ring structure (ketone). A mechanism involving a retroaldol reaction, a nucleophilic opening of the epoxide, and a subsequent acetoxy elimination reaction was proposed. 相似文献
7.
R. R. Gataullin F. F. Minnigulov T. V. Khakimova A. A. Fatykhov L. V. Spirikhin I. B. Abdrakhmanov 《Russian Chemical Bulletin》2002,51(7):1329-1331
The reactions of 2-(cyclohex-2-enyl)-4,5-difluoroaniline or N-methyl-2-(cyclohex-2-enyl)aniline with I2 in CCl4 in the presence of NaHCO3 give 1-iodo-1,2,3,4,4a,9a-hexahydrocarbazoles, which isomerize in MeCN into the corresponding 3-iodo-2,4-propano-1,2,3,4-tetrahydroquinolines in quantitative yields. 相似文献
8.
2-Bromo-3-iodo- and 3-bromo-2-chlorothiophene react with magnesium in the presence of 1,2-dibrornoethane to give 2-halo-3-thiophene magnesium halide which opens a useful route to 2,3-disubstituted thiophenes having an electron-withdrawing group in the 3-position. 相似文献
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A novel approach for the synthesis of 2,4-dialkyl-3-hydroxybutanolides, having three successive stereogenic centers, by an acid-catalyzed ring-switch reaction of 2-(2-hydroxyalkyl)lactams is described. This transformation was applied to the synthesis of the key intermediates of teromerase inhibitor UCS1025A. 相似文献
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Denis S. Baranov Aleksey A. Ryabichev Victor I. Mamatyuk Yurii V. Gatilov Victor G. Kartsev Sergei F. Vasilevsky 《Mendeleev Communications》2012,22(2):114-116
Reaction between 2-alkyl-4-arylbut-3-yn-2-ols and guanidine in refluxing pyridine affords 2-amino-5,5-dialkyl-4-arylmethylidene-2-oxazolines. 相似文献
14.
Joseph J. Brophy Chang-Ming Sun Berhane Tecle Robert F. Toia 《Journal of mass spectrometry : JMS》1989,24(8):609-614
The detailed mass spectral fragmentation pathways of a series of both naturally occurring and synthetic 5-methyl-3-alkyl-2-aIkenylpyrazines have been elucidated with the aid of deuterium labels placed specifically in the alkenyl side-chain. The influence on the fragmentation pattern of the stereochemistry of the alkenyl group as well as the relative placement of the groups on the pyrazine nucleus have also been evaluated. This provides information of some diagnostic value in the assignment of structures by mass spectrometry to new compounds within this class. 相似文献
15.
Liquid and solid-state infrared spectra were obtained for 1-iodo-2-methylpropane and 1-iodo-3-methylbutane. The C-I stretching bands of the PC and PH' conformers of the propane were observed at 601 and 582 cm?1, respectively, and those of the PC and PH conformers of the butane were observed at 595 and 512 cm?1. Both conformers of each compound are present in the amorphous solid. Only the more sterically hindered PH' conformer is present in the crystalline solid of the propane, and only the PH conformer is present in the crystals of the butane. Vibrational assignments were made for both conformers of each compound with the aid of normal coordinate calculations. The increase in C-I stretching frequency of the PH' conformer of the propane from the normal value in alkyi iodides (from ca. 500 to 582 cm?1) is attributed to the increased contribution of C-C stretch and decreased contribution of C-I stretch. 相似文献
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Allen Ko Aaron Lam Jeffrey Li Edyta M. Greer David J. Szalda Sasan Karimi Gopal Subramaniam Keith Ramig 《Tetrahedron letters》2014
2,4-Diphenyl-3H-1-benzazepine is deprotonated with either LDA or KHMDS. The resulting anion is alkylated with alkyl halides or MeOTs, giving either products of alkylation at C3, or at N, or a mixture of both. The regioselectivity depends on the base, presence of the complexing agent HMPA, and the leaving group of the alkylating agent. Using MeI as alkylating agent gives exclusively the C3-methylated product, while using MeOTs gives exclusively the N-methylated product. The N-alkylated products show evidence of stereodynamic behavior in their NMR spectra. 相似文献
18.
O. Yu. Valiakhmetova S. A. Bochkor V. V. Kuznetsov 《Chemistry of Heterocyclic Compounds》2010,46(8):1006-1010
Computer modeling using the quantum-chemical empirical MM+ method and nonempirical RHF//6-31G(d), MP2//6-31G(d), and, in individual
cases, RHF//3-21G methods was employed to study the potential energy surface of 2,4-dialkyl-1,3,2-dioxaborinanes. The optimal
geometry and 1H NMR spectral data gave values for ∆G
0 of the methyl and hexyl substituents at C-4 of the heterocyclic ring equal to 0.6 and 1.6 kcal/mol, respectively. 相似文献
19.
L. M. Potikha A. R. Turelyk V. A. Kovtunenko 《Chemistry of Heterocyclic Compounds》2011,47(4):452-455
Cyclization of 1-alkyl-3-[(2Z)-2,4-diaryl-4-oxobut-2-en-1-yl]-1H-benzimidazol-3-ium bromides occurs in the presence of MeONa
at a reduced temperature of 5–10°C via a 1,5-electrocyclization mechanism to give 3a,4-dihydro-3H-pyrrolo[1,2-a]benzimidazoles. These are unstable under the reaction conditions and are readily converted to {1-[2-(alkylamino)phenyl]-4-phenyl-1H-pyrrol-3-yl}(phenyl)methanones. 相似文献
20.
V. P. Zhestkov V. G. Zabrodnaya A. I. Chernyshev 《Chemistry of Heterocyclic Compounds》1995,31(11):1302-1306
The reaction of the esters of N-alkyl-N-phenylhydrazinocarbonylpropionic acids with phosphorus oxychloride in dioxane or with phosgene in benzene leads to the formation of the esters of 1-alkyl-2-aminoindolyl-3-acetic acids and of the corresponding N-alkyl-N-phenylaminosuccinimides.All-Russian Center for the Safety of Biologically Active Substances (ARC BAS), Kupavna, Moscow Oblast 142450. Translated from Khimiya Geterots iklicheskikh Soedinenii, No. 11, pp. 1502–1506, November, 1995. Original article submitted September 2, 1995. 相似文献