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1.
R. Bacardit J. Cervell P. de March J. Marquet M. Moreno-Maas J. L. Roca 《Journal of heterocyclic chemistry》1989,26(5):1205-1212
New derivatives of dehydroacetic acid and triacetic acid lactone functionalized at both C-5 and at the methyl group at C-6 have been synthesized as intermediates for the preparation of thromboxane B2 analogues. 6-Mercaptomethyl-4-methoxy-2-pyrone and some derived thioethers have been also prepared. New thioether derivatives of O-alkyloximes of dehydroacetic acid have been synthesized and tested for herbicidal activity. 相似文献
2.
Triacetic acid lactone methyl ether, 4, can be lithiated at C-3 under kinetically controlled conditions. Further reaction with (E)-2-methyl-3-(4-nitrophenyl)propenal results in an unusual condensation at C-3. 相似文献
3.
Lafitte VG Aliev AE Hailes HC Bala K Golding P 《The Journal of organic chemistry》2005,70(7):2701-2707
[structure: see text] 2-Ureido-4-[1H]-pyrimidinones have been reported to dimerize via quadruple hydrogen bonding systems with dimerization constants >10(6) M(-1) in CDCl3. The dimerization constant, K(dim), is dependent on the solvent as well as the ring-substituents present, where previously alkyl (e.g., R1 = Me) and aromatic moieties (e.g., R1 = p-NO2C6H4, R1 = C6H2(OC13H27)3) have been incorporated at the C-6 position. To assess the influence of alternative, functionalizable, electron-donating groups on the dimerization motif and tautomeric distribution of isomers, the synthesis of compounds possessing aminophenyl functionality at the C-6 position has been achieved. NMR spectroscopy chemical shift analysis revealed that compound 2 (R1 = p-NH2C6H4, R2 = C6H13) existed as the 2-ureido-4-pyrimidinol dimeric DADA array in DMSO-d6, where a dimerization constant of 46 M(-1) was determined. This is the first time that a ureidopyrimidinone quadruple hydrogen bonding DADA array has been observed in pure DMSO, a highly polar solvent. The azo-derivative 5 of compound 2 was prepared which also adopted the pyrimidin-4-ol form in DMSO-d6. Compounds 7, 10 and 11 were then synthesized containing a more hydrophilic PEG unit in the lateral chain and the tautomeric distributions were determined. 相似文献
4.
P. De March M. Moreno-Maas R. Pi I. Ripoll F. Snchez-Ferrando 《Journal of heterocyclic chemistry》1985,22(6):1537-1542
Twenty-five different brominated derivatives of 4-hydroxy-6-methyl-2-pyrone (triacetic acid lactone) and 3-acetyl-4-hydroxy-6-methyl-2-pyrone (dehydroacetic acid) have been prepared. Fifteen derivatives have not been previously described and the preparations of a few known products have been improved. Bromination at C-3, C-5, methyl group at C-6 and deacetylations at C-3 have been the types of reactions used. 相似文献
5.
Hiroshi Hori Tatsuo Nakajima Yoshihiro Nishida Hiroshi Ohrui Hiroshi Meguro 《Journal of carbohydrate chemistry》2013,32(4):585-600
Photobromination and the succeeding deuteration with tri-n-butyltindeuteride were performed on eight l,6-anhydro-2,3,4-tri-O-benzoylhexopyranoses to give C-6 chirally deuterated hexopyranoses. The stereochemistry of these two reactions are discussed in terms of steric effects of substituents at C-2, C-3 and C-4 of 1,6-anhydrohexopyranoses. 相似文献
6.
Three different routes have been investigated for the preparation of 6-aryl-N-(1-arylethyl)thienopyrimidin-4-amines. First the possibilities of selective Suzuki reactions on 6-bromo-4-chlorothienopyrimidine were investigated. The preference for mono arylation at C-6 could be increased, in the case of Pd(PPh3)4 catalysis, by reducing the water content of the reaction, or by using less electron rich Pd-ligands. The highest selectivity was obtained with Pd(OAc)2 or Pd2(dba)3, while reactions with the more electron rich Pd(PPh3)4 and especially XPhos gave a lower mono- to dicoupled product ratio. Secondly, two alternative strategies avoiding this selectivity issue were tested. Suzuki reaction on C-6 of 6-bromothienopyrimidin-4(3H)-one (three examples) proceeded in 70-89% yield using Pd(PPh3)4 in dioxane/water. Similar conditions on 4-amino-6-bromo-thienopyrimidine (eight examples) gave 67-95% yield. The reaction could be performed with boronic acids containing nonprotected phenolic groups in the ortho, meta and para positions. By prolonging the reaction time, coupling with sterically crowded arylboronic acids was also efficient. Diarylation of 6-bromo-4-chlorothienopyrimidine gave the corresponding 4,6-diarylated derivatives in 71-80% yield depending on the nature of the arylboronic acid. 相似文献
7.
Hiroto Kubo 《Tetrahedron letters》2008,49(7):1203-1207
The 1,4-addition of the enolate generated from α-methylated acetoacetate incorporated at C-4 of methyl 6-deoxy-2,3-di-O-(tert-butyldimethylsilyl)-α-d-glucopyranoside to methyl vinyl ketone, followed by aldol condensation of the resulting 1,4-addition product under two base-mediated conditions, provided 4-O-functionalized d-glucose derivatives with high diastereoselectivity. These products install a 3-methyl-2-cyclohexen-1-one-4- (or -6-) carboxylic acid as the O-4 ester, in which C-4 or C-6 is an asymmetric quaternary carbon. Removal of the sugar template from those aldol condensation products provided synthetically useful 3,6-dimethyl-2-cyclohexen-1-one-6-carboxylic acid and 3,4-dimethyl-2-cyclohexen-1-one-4-carboxylic acid derivatives both in high enantioenriched forms. 相似文献
8.
Hassan Kefayati Maryam Fakhriyannejad Ali A. Mohammadi 《Phosphorus, sulfur, and silicon and the related elements》2013,188(7):1796-1804
New 3,4-dihydropyrimidin-2-ones having a phenyl moiety at C-5 and C-6 have been prepared by a microwave-assisted Biginelli–like reaction by a three-component, one-pot condensation of an aromatic aldehyde, deoxybenzoin and urea, or thiourea using TMSCl and Co(OAc) 2 .4H 2 O as an efficient Lewis acid catalyst. 相似文献
9.
4-Aryl-6-methyl-3,4-dihydro-2(1H)-pyrimidinone esters (DHPMs) readily undergo metalation at the C-6 methyl (vinylogous ester) position on treatment with lithium diisopropylamide at -10 degrees C. The resulting anion intermediates can be treated with electrophilic reagents to afford functionalized DHPMs that have been chemically elaborated mainly at the C-6 position. Di- and trianion formation is also possible at both the vinylogous methyl and NH positions when reactions are performed with excess equivalents of the base. 相似文献
10.
Tatjana Gazivoda Svjetlana Krištafor Mario Cetina Ante Nagl Silvana Raić-Malić 《Structural chemistry》2008,19(3):441-449
C-5 and C-6 disubstituted pyrimidine derivatives 2–7 were synthesized. Introduction of the aryl rings at C-5 of pyrimidine moiety in 5 and 6 was performed using palladium-catalyzed Stille cross-coupling reaction. The novel C-6 fluorophenylalkylated 5-phenylpyrimidine
derivative (7) was prepared by lithiation of 5-phenylpyrimidine (6) and subsequent reaction of thus obtained organolithium intermediate with p-fluoroacetophenone. The structures of 3, 4 and 6 were determined by X-ray crystal structure analysis. Both methoxy groups in these structures adopt a synperiplanar conformation with respect to the N1 and N3 atoms of the pyrimidine ring. The molecules of 3 and 4 are linked through weak Br···Br interactions into zig-zag chains. The molecules of 6 are assembled into layers by one C–H···O hydrogen bond, C–H···π and aromatic π···π stacking interactions. 相似文献
11.
Jairo Quiroga Jorge Trilleras Braulio Insuasty Manuel Nogueras Justo Cobo 《Tetrahedron letters》2008,49(39):5672-5675
A series of 6-aminopyrimidines are cyanoacetylated with a mixture of cyanoacetic acid and acetic anhydride. When pyrimidin-4(3H)-ones are used as substrates, the substitution occurs at C-5, however, when the substrates are substituted pyrimidines at the C-2 and C-4, the cyanoacetylation takes place at the exocyclic amino group. 相似文献
12.
S. Asghari Ahmed Peter W. Hickmott Maurice W. Cooper Ian A. Stenhouse 《Magnetic resonance in chemistry : MRC》1980,14(4):296-299
The 220 MHz 1H NMR spectra of 6-hydroxy-7-methyl-6-phenyladamantane-2,4-dione, 6-hydroxy-5,7-dimethyl-6-phenyladamantane-2,4-dione, and 6-hydroxy-7,9-dimethyl-6-phenyladamantane-2,4-dione have been determined and complete proton assignments carried out with the aid of multiple irradiation. The stereochemistry of the C-6 and C-9 chiral centres have been determined and some of the factors affecting the magnitude of the geminal, vicinal and W coupling constants are discussed. 相似文献
13.
H. ScheerH. Wolf 《Tetrahedron》1972,28(23):5839-5856
The diastereomeric 9-hydroxy pheophorbides 3a, b-1, 2 and 4a, b-1, 2 were prepared by reduction of the 10-alkoxy pheophorbides 1a, b and 2a, b with NaBH4. Their absolute configuration at C-10 was determined by NMR- and ORD/CD-measurements as well as chemical correlation, the configuration at C-9 by IR- and mainly NMR-spectroscopy. For this purpose, the NMR-spectra of the 9-hydroxy pheophorbides 3a, b-1, 2 had completely to be assigned with the aid of the selectively deuterated alcohols 5a, b-1, 2. The configuration at C-10 is stable under the conditions of the alkaline reduction while C-9 partially epimerizes. The acidic alcoholysis of 3a, b-1, 2, however, proceeds by equilibration at C-10 and almost complete retention at C-9. The H-bonds between the 9-OH group and the C-10 substituents (-COOCH3, -OCH3 were investigated by NMR and IR spectroscopy. 相似文献
14.
Thevis M Beuck S Höppner S Thomas A Held J Schäfer M Oomens J Schänzer W 《Journal of the American Society for Mass Spectrometry》2012,23(3):537-546
Structure elucidation of steroids by mass spectrometry has been of great importance to various analytical arenas and numerous
studies were conducted to provide evidence for the composition and origin of (tandem) mass spectrometry-derived product ions
used to characterize and identify steroidal substances. The common product ion at m/z 97 generated from androst-4-ene-3-one analogs has been subject of various studies, including stable isotope-labeling and
(high resolution/high accuracy) tandem mass spectrometry, but its gas-phase structure has never been confirmed. Using high
resolution/high accuracy mass spectrometry and low resolution tandem mass spectrometry, density functional theory (DFT) calculation,
and infrared multiple photon dissociation (IRMPD) spectroscopy employing a free electron laser, the structure of m/z 97 derived from testosterone was assigned to protonated 3-methyl-2-cyclopenten-1-one. This ion was identified in a set of
six cyclic C6H9O+ isomers as computed at the B3LYP/6-311++G(2d,2p) level of theory (protonated 3-methyl-2-cyclopenten-1-one, 2-methyl-2-cyclopenten-1-one
and 2-cyclohexen-1-one). Product ions of m/z 97 obtained from MS2 and MS3 experiments of protonated 3-methyl-2-cyclopenten-1-one, 2-methyl-2-cyclopenten-1-one, 2-cyclohexen-1-one, and testosterone
corroborated the suggested gas-phase ion structure, which was eventually substantiated by IRMPD spectroscopy yielding a spectrum
that convincingly matched the predicted counterpart. Finally, the dissociation pathway of the protonated molecule of testosterone
to m/z 97 was revisited and an alternative pathway was suggested that considers the exclusion of C-10 along with the inclusion of
C-5, which was experimentally demonstrated with stable isotope labeling. 相似文献
15.
Rauter AP Fernandes AC Czernecki S Valery JM 《The Journal of organic chemistry》1996,61(11):3594-3598
A five-step synthesis from 3 leading to a partially protected amipurimycin sugar moiety 14 in an overall yield of 47% is described and includes deoxygenation at C-4 and regio- and stereoselective construction of the branched chain. Deoxygenation at C-4 of 3 was possible by three different methods. Radical reduction with tri-n-butyltin hydride of the appropriate phenoxythiocarbonyl derivative afforded the desired deoxysugar 5 in 47% overall yield together with the secondary products 6 and 7 due to depivaloylation at C-2 and elimination of methanol. The most adequate deoxygenation procedure used the system Ph(3)P/I(2)/imidazole which led to the preparation of 5 in one step in 61% yield. When the system Ph(3)PBr(2)/Ph(3)P was tried, only 8 was formed due to elimination of methanol. The synthesis of 5 was then accomplished by reaction of 8 with methanol in the presence of triphenylphosphine hydrobromide in 37% overall yield. Branched-chain construction was accomplished by Wittig reaction of 5 with [(ethoxycarbonyl)methylene]triphenylphosphorane, followed by osmilation and reduction with lithium aluminum hydride. Isopropylidenation of 14 afforded 16 with a free hydroxy group at C-6 for chain elongation and further synthesis of amipurimycin. 相似文献
16.
Treatment of cis- and trans-4-methyl-5-phenyl oxazolidinones 2 and 3 with excess butyllithium at 0°C results in C-5 epimerisation, via a common intermediate N,C-5-dianion, generating after protonation a 1:4 mixture of 2:3. 相似文献
17.
We have previously reported on a series of 4-anilino-6,7-dialkoxy-3-quinolinecarbonitriles as potent inhibitors of MEK1 kinase. Herein, we describe our synthetic efforts toward a series of 4-anilino-6-alkoxy-7-amino-3-quinolinecarbonitriles. In the course of this work, we were able to rapidly construct a library of 4-anilino-6-alkoxy-7-amino-3-quinolinecarbonitriles by simultaneous or sequential SN2 (displacement) reactions on the C-6 chloroalkoxy moiety and SNAr (addition/elimination) reactions at C-7 with nucleophilic amines. 相似文献
18.
A series of novel d-glucose derivatives, functionalized at the C-2 or the C-6 position with an iminodiacetic acid moiety for transition-metal complexation, has been prepared. The sugar and the metal-chelating parts are separated by either propyl or octyl chains and were introduced by the reaction of bromoalkylamine. Either N-1-Boc-3-bromopropylamine (17) or N-(8-bromooctyl)phthalimide (19) reacted with methyl 3,5,6-tri-O-benzyl-alpha-beta-d-glucofuranoside (4) (C-2 position) and 1,2:3,5-(O-methylene)-alpha-d-glucose (11) (C-6 position), respectively, in the presence of sodium hydride in DMF at room temperature, affording the desired intermediates. For aminopropyl derivatives, yields varied between 57% and 65%, and for aminooctyl derivatives, yields varied between 40% and 71%. After deprotection of the amine functionality, the metal chelate was built up by dialkylation (6a-c and 13a,b) with methyl bromoacetate in the presence of triethylamine under reflux in THF. Yields varied between 56% and 69% for the glucose modified at the C-2 position and between 58% and 62% for the one modified at the C-6 position. All compounds were characterized by 1H or 13C NMR or both, IR, and mass spectroscopy. Final products were isolated as a mixture of alpha and beta anomers. 相似文献
19.
Synthesis of C-3' methyl taxotere (docetaxel) 总被引:1,自引:0,他引:1
Protected (3R,4S)-N-Boc-3-hydroxy-4-methyl-4-phenylazetidin-2-one has been synthesized stereoselectively and used to esterify protected 10-desacetylbaccatin III to give, following removal of the protecting groups, novel C-3' methyl taxotere (docetaxel). 相似文献
20.
Lakshman MK Hilmer JH Martin JQ Keeler JC Dinh YQ Ngassa FN Russon LM 《Journal of the American Chemical Society》2001,123(32):7779-7787
Suzuki-Miyaura cross-coupling of haloaromatic compounds with arylboronic acids provides a simple entry to biaryl systems. Despite its ease, to date, there are no detailed investigations of this procedure for deoxynucleoside modification. As shown in this study, a wide variety of C-6 arylpurine 2'-deoxyriboside (C-6 aryl 2'-deoxynebularine analogues) and C-2 aryl 2'-deoxyinosine analogues can be conveniently prepared via the Pd-mediated cross-coupling of arylboronic acids with the C-6 halonucleosides, 6-bromo- or 6-chloro-9[2-deoxy-3,5-bis-O-(tert-butyldimethylsilyl)-beta-D-erythro-pentofuranosyl]purine (1 and 2), and the C-2 halonucleoside, 2-bromo-O(6)-benzyl-3',5'-bis-O-(tert-butyldimethylsilyl)-2'-deoxyinosine (3). Although bromonucleoside 1 proved to be a good substrate for the Pd-catalyzed Suzuki-Miyaura cross-couplings, we have noted that for several C-6 arylations, the chloronucleoside 2 provides superior coupling yields. Also described in this study is a detailed evaluation of catalytic systems that led to optimal product recoveries. Finally, a comparison of the C-C and C-N bond-forming reactions of deoxynucleosides is also reported. On the basis of this comparison, we provide evidence that C-N bond formation at the C-6 position, leading to N-aryl 2'-deoxyadenosine analogues, is more sensitive to the ligand used, whereas C-C bond-forming reactions at the same position are not. In contrast to the ligand dependency exhibited in C-N bond formation at the C-6 position, comparable reactions at the C-2 position of purine deoxynucleosides proceed with less sensitivity to the ligand used. 相似文献