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1.
Novel steroidal phosphoramidate conjugates of 3'-azido-2',3'-dideoxythymidine(AZT)and amino acid esterswere synthesized and determined by positive and negative ion electrospray ionization mass spectrometry.The MSfragmentation behaviors of the steroidal phosphoramidate conjugates have been investigated in conjunction withtandem mass spectrometry of ESI-MS/MS.There were three characteristic fragment ions in the positive ion ESImass spectra,which were the Na adduct ions with loss of steroidal moiety,amino acid ester moiety from pseudomolecular ion(M Na)~ ,and the phosphoamino acid methyl ester Na adduct ion by α-cleavage of the phosphora-midate respectively.The main fragment ions in negative ion ESI mass spectra were the ion(M-HN_3)~-,the ion(M-AZT-H)~-,and the ion(M-steroidal moiety-H)~- besides the pseudo molecular ion(M-H)~-.Thefragmentation patterns did not depend on the attached amino acid ester moiety. 相似文献
2.
The positive ion mass spectrum of allogibberic acid was examined and fragmentation routes involving the carbon skeleton are proposed on the basis of mass measurements and metastable ion observations. The results are compared with the mass spectra of 3-hydroxy-epiallogibberic acid, as well as gibberellin A3 (GA3), 3-epi-GA3, 3-dehydro-GA3 and iso-GA3, the latter compounds all being capable of undergoing aromatization of ring A giving a key ion corresponding to the molecular ions of the allogibberic acid and 3-hydroxy-epiallogibberic acid models, respectively. All the gibberellin derivatives investigated show the same fragmentation of the skeleton. Thus, the behaviour under electron impact of the GA3 type gibberellins follows a general pattern. 相似文献
3.
N. A. Pankrushina A. G. Druganov I. Yu. Bagryanskaya Yu. V. Gatilov M. M. Shakirov V. A. Raldugin 《Chemistry of Natural Compounds》1994,30(5):613-618
A mixture of gibberellin A3 derivatives with 1(10)-ene-2β,3β-diol and 1(10)-ene-2α,3β-diol (2:5) groups, readily obtained from gibberellin A3, has been used for a new and simple synthesis of gibberellin A8 and its esters. The hydrolysis of GA3 and the iodolactonization of a mixture of the 2-epimers was carried out in aqueous solution in a single flask, as also was a synthesis of GA56 from GA3 by a method that we have modified. The mixture of 1β-iodides of GA8 and GA56 was separated by chromatography on SiO2 in the form of methyl or p-bromophenacyl esters which were then deiodinated and the methyl or p-bromphenacyl ester of GA8 was isolated. Free GA8 was obtained by the dephenylation of the latter ester. By two-dimensional NMR spectroscopy we succeeded in assigning all the signals in the13C and1H NMR spectra of the methyl esters of GA8 and GA56. In an attempt to obtain GA5 methyl ester by the action of trimethylchlorosilane/sodium iodide on the 2α,3β-diol system in GA56 methyl ester, the 8,13-epimer of the latter was formed, the structure of its molecule being established from the results of X-ray structural analysis. 相似文献
4.
Conclusion A study was made of the photolytic opening of the epoxide ring in the methyl ester of the 1,2-epoxy-3-keto derivative of gibberellin A1, which led to the formation of the methyl ester of 1,3-dihydroxyepial-logibberic acid and the methyl ester of the 1-hydroxy-3-keto derivative of gibberellin A1.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 459–461, February, 1972. 相似文献
5.
CHEN Wei-zhu GAO Yu-xing BAI Yong-gang HAN Da-xiong ZHAO Yu-fen 《高等学校化学研究》2006,22(6):732-737
Amino acid methyl ester phosphates were synthesized and determined by using positive-ion mode dectrospmy ionization mass spectrometry(ESIMS) in combination with multistage tandem mass spectrometry. The fragmentation pathways were investigated, and it was observed that most fragment ions contained the phosphoryl group. It was interesting to observe that the fragmentation pathways of the protonated molecule show some differences when compared with those of the sodium ion adduct. The methoxy group of amino acid methyl ester can migrate from the carbonyl group to the phosphoryl group in the sodium ion adduct. 相似文献
6.
Summary In the mass spectrum of the 3 -epimer of the methyl ester of gibberellin As there is an increased intensity of the peaks connected with the elimination of the lactone ring. For the 3-keto derivatives of the gibberellin A1 series with substituents at C1 the formation of ions corresponding to the splitting out of the C1-C2-C3 fragment is characteristic.N. D. Zelinskii Institute of Organic Chemistry, Academy of Sciences of the USSR. M. M. Shemyakin Institute of Bioorganic Chemistry, Academy of Sciences of the USSR. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 486–490, July–August, 1975. 相似文献
7.
Ilpo O. O. Korhonen 《Journal of mass spectrometry : JMS》1982,17(11):553-557
The mass spectral fragmentations of methyl mono- and dichlorobutanates have been studied. Deutrium labelling and metastable ion analysis were used to elucidate the fragmentation mechanisms. The molecular ion peaks of the esters are weak and show only in the spectra of the monochloro isomers. A McLafferty rearrangement gives the base peaks in the spectra of methyl 2-chloro-, 4-chloro- and 4,4-dichlorobutanoate; α-cleavage, [COOCH3]+, in methyl 2,2- and 2,4-dichlorobutanoate; [M? Cl]+, in methyl 3-chlorobutanoate; [M? Cl? HCl]+, in methyl 3,4-dichlorobutanoate; [M? Cl? CH2CO]+, in methyl 3,3-dichlorobutanoate and [M? Cl? COOCH3]+˙, in methyl erythro- and threo-2,3-dichlorobutanoate. The mass spectra of the stereoisomers are nearly identical, the loss of a chlorine atom and the McLafferty rearrangement giving the higher peaks in the spectrum of the threo form. 相似文献
8.
《Angewandte Chemie (International ed. in English)》2017,56(47):15146-15149
Gas–liquid mass transfer of gaseous reactants is a major limitation for high space–time yields, especially for O2‐dependent (bio)catalytic reactions in aqueous solutions. Herein, oxygenic photosynthesis was used for homogeneous O2 supply via in situ generation in the liquid phase to overcome this limitation. The phototrophic cyanobacterium Synechocystis sp. PCC6803 was engineered to synthesize the alkane monooxygenase AlkBGT from Pseudomonas putida GPo1. With light, but without external addition of O2, the chemo‐ and regioselective hydroxylation of nonanoic acid methyl ester to ω‐hydroxynonanoic acid methyl ester was driven by O2 generated through photosynthetic water oxidation. Photosynthesis also delivered the necessary reduction equivalents to regenerate the Fe2+ center in AlkB for oxygen transfer to the terminal methyl group. The in situ coupling of oxygenic photosynthesis to O2‐transferring enzymes now enables the design of fast hydrocarbon oxyfunctionalization reactions. 相似文献
9.
The correct structure has been established for the compound obtained on the treatment of the methyl ester of gibberellin A3 with zinc in boiling acetic anhydride, to which the erroneous structure (II) was previously assigned. A mechanism of the formation of compound (II) is suggested which includes an intramolecular diene condensation between an acetate carbonyl group and the conjugated diene system in the intermediate mixed anhydride (V). 相似文献
10.
Ellis V. Brown Andrew C. Plasz Stanley R. Mitchell 《Journal of heterocyclic chemistry》1970,7(3):661-665
The mass spectra of all the aminoquinolines, the 2–, 3– and 4-amino-1,5-naphthyridines, some amino-1,6-naphthyridines, and two amino-1,8-naphthyridines with methyl substituents are reported. The major fragment in the aminoquinolines is formed by the loss of HCN from the molecular ion. The most abundant fragment in the aminonaphthyridines is formed by the loss of HCN from the molecular ion except in the 2-amino-1,5-naphthyridine isomer. In both 1,8-naphthyridine isomers investigated, the loss of C2H2 is an alternate fragmentation pathway of significance. In all of the compounds investigated, the loss of the primary amino group from the molecular ion was found to be an insignificant fragmentation. 相似文献
11.
Braulio M. Fraga Carlo BressaVictoria González-Vallejo Sergio SuárezRicardo Guillermo 《Tetrahedron letters》2011,52(52):7138-7140
The reaction of different 7-oxo-ent-kaur-16-ene derivatives with diacetoxyiodobenzene has been evaluated for the preparation of gibberellin analogues. Thus, the reaction of 7-oxo-ent-kaur-16-en-18-oic acid methyl ester (3) with this reagent afforded 4-epi-GA12 dimethyl ester (6). This reaction constitutes a good procedure for the preparation of this type of compounds. In some cases, alternative reactions that led to the introduction in the substrate of a conjugated 5,6-double bond or to the formation of a ketal at the 6-position were also produced. The formation of these compounds, or of gibberellin analogues, depends on the neighbouring group participation of the different C-18 and C-19 substituents at C-4. 相似文献
12.
Xueguang Lv Jiaxi Xu 《Phosphorus, sulfur, and silicon and the related elements》2013,188(10):1151-1160
Abstract The negative ion mass spectrometry of N-benzyloxycarbonyl and N-ethoxycarbonyl 1-aminoarylmethylphosphonic methyl, ethyl, and phenyl monoesters was investigated under electrospray ionization conditions. Their fragmentation pathways are proposed and supported by collisional activated dissociation product-ion spectrometry. All of the deprotonated molecules preferentially eliminate a molecule of benzyl alcohol or ethanol first to yield isocyanato-alkylphosphonate anions, which further generate phosphonate ions by the loss of carbon monoxide, phenol or alcohol, carbon monoxide plus arenes. The isocyanato-sulfonate anions can further cyclize to generate 3-aryl-2-phenoxy-1,2,4-oxaphosphazolidine-2,5-dione amide anions, which can undergo rearrangements by the loss of carbon dioxide, metaphosphorous acid phenyl ester, or carbon dioxide plus metaphosphorous acid phenyl ester, respectively, to give rise to nitrogen-containing anions. The title compounds show an obviously different fragmentation in the negative ion mode from that in the positive ion mode under the electrospray ionization conditions. 相似文献
13.
Exposure of ent-kaura-2,16-dien-19-ol (1) or its succinate (2) to resuspended mycelia of G. fujikuroi has produced a complex mixture of acids which after methylation gave the esters of two C19 (24) and (30) and five C20 gibberellins (4, 11, 20, 32 and 33). The triester (32) and the lactone ester (24) have been prepared before from the esters of gibberellin A13 (8) and gibberellin A4 (26) respectively. The structures of the other metabolites were assigned on spectroscopic data and by chemical transformations. Thus the lactone diester (4) has been converted to the known keto triester (6). The epoxide (11) has been related to gibberellin A14 (14) and the aldehyde (33) has been related to gibberellin A13 trimethyl ester (8) by way of the triol (34). Selective de-epoxidation of the 16,17-epoxy function in diepoxides has provided a route from the dienes (20 and 24) to the epoxides (11 and 30) respectively, but not from the ester of gibberellin A5 (23) to that of gibberellin A6 (29). On the other hand the latter can be obtained by epoxidation of gibberellin A5 methyl ester trifluoroacetate. Backfeeding experiments carried out with the epoxy diacid (12), the diene diacid (21) and the derived diol (39) indicate pathways connecting the various metabolites. The natural gibberellins A5 and A6 were shown to be formed in some of the backfeeding experiments. 相似文献
14.
V. P. Zvolinskii P. I. Zakharov S. G. Poshivalov V. K. Shevtsov V. G. Pleshakov T. S. Seitembetov N. S. Prostakov 《Chemistry of Heterocyclic Compounds》1977,13(10):1094-1098
The mass spectral behavior of five derivatives of the 4-azaphenanthrene series — 1,3-dimethyl-(I), 2,3-dimethyl-(II), 1,2,3,-trimethyl-(III), 1,2,3-trimethyl-8-nitro-(IV), and 1,3-dimethyl-6,7-dinitro-4-azaphenanthrene (V) — was studied. The stabilities of the molecular ions with respect to gragmentation (WM) are higher by a factor of two or more for the methyl-substituted I–III than for nitro derivatives IV and V. The intensity of the [M-H]+ ion peak in the mass spectra of I–V does not depend on the number of methyl groups but only on their positions: the presence of a CH3 group in the 2 position leads to an [M-H]+ ion that is 1.5 times more intense than when there is a methyl group in the 1 position. The molecular ions of I–V do not eliminate HCN molecules; this constitutes evidence for the absence of randomization of their methyl groups. The presence of a CH3 substituent in the 1 or 2 position does not affect the intensity of the [M-CH3]+ ion peaks, while the simultaneous presence of CH3 groups attached to the C1 and C2 atoms increases the intensity of the [M-CH3]+ fragment peak by a factor of two. In the mass spectra of nitro derivatives IV and V, [M-O]+, [M-OH]+, [M-NO]+, and [M-NO2]+ fragments are observed in the first step of the fragmentation of the M+ ion, whereas the [M-CO]+ ion peak characteristic for the dissociative ionization of 1-nitronaphthalene is also observed for 8-nitro-substituted IV.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1365–1369, October, 1977. 相似文献
15.
N. A. Pankrushina A. G. Druganov I. Yu. Bagryanskaya Yu. V. Gatilov M. M. Shakirov V. A. Raldugin 《Chemistry of Natural Compounds》1995,30(5):613-618
A mixture of gibberellin A3 derivatives with 1(10)-ene-2,3-diol and 1(10)-ene-2,3-diol (2:5) groups, readily obtained from gibberellin A3, has been used for a new and simple synthesis of gibberellin A8 and its esters. The hydrolysis of GA3 and the iodolactonization of a mixture of the 2-epimers was carried out in aqueous solution in a single flask, as also was a synthesis of GA56 from GA3 by a method that we have modified. The mixture of 1-iodides of GA8 and GA56 was separated by chromatography on SiO2 in the form of methyl or p-bromophenacyl esters which were then deiodinated and the methyl or p-bromphenacyl ester of GA8 was isolated. Free GA8 was obtained by the dephenylation of the latter ester. By two-dimensional NMR spectroscopy we succeeded in assigning all the signals in the13C and1H NMR spectra of the methyl esters of GA8 and GA56. In an attempt to obtain GA5 methyl ester by the action of trimethylchlorosilane/sodium iodide on the 2,3-diol system in GA56 methyl ester, the 8,13-epimer of the latter was formed, the structure of its molecule being established from the results of X-ray structural analysis.Novosibirsk Institute of Organic Chemistry, Siberian Division of the Russian Academy of Sciences. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 663–669, September–October, 1994. 相似文献
16.
The kinetic method was used to determine the proton affinities of methyl esters of several saturated fatty acids. Decompositions of the proton-bound dimers of the methyl esters, AHB+, were observed under different conditions with two instruments. The proton affinities (PAs) of the methyl esters increase continually with increasing carbon number in the acid. Equilibrium and initial rate experiments were performed with a Fourier transform ion cyclotron resonance mass spectrometer on the methyl ester of the C22 saturated acid (methyl behenate). These experiments give values for PA (methyl behenate) that are perhaps slightly lower than those obtained with the kinetic method. The PAs of the methyl esters of the fatty acids could be correlated with the equation: PA (ester) = (40.0 ± 2.5)*log(n) + (784.7 ± 3.9) kJ/mol or PA (ester) = (864 ± 2) − (479 ± 41)/n, wheren = number of atoms in the molecule. Proton affinities of smaller sets of 1-alkylamines and 1-alkanols can be fit to similar equations. 相似文献
17.
Nobutaka Takahashi Noboru Murofushi Saburo Tamura Nobuhide Wasada Hiroko Hoshino Toshikazu Tsuchiya Shin-Ichi Sasaki Tetsumi Aoyama Eiji Watanabe 《Journal of mass spectrometry : JMS》1969,2(7):711-722
Based on the element maps of twenty-two gibberellin methyl esters fragmentations are discussed, which are characteristic of the common structural features as well as structural modification in gibberellin homologues. 相似文献
18.
Fatty acids with a hydroxyl moiety at the C-3 position are found widely in bacterial lipids, but only rarely in mammalian lipids. The mass spectra of the methyl ether derivative of these hydroxy acids exhibit an intense ion at m/e 75, rather than the rearrangement ion at m/e 74 more typical of fatty acid methyl esters. The mass spectrometric behavior of several 3-methoxy fatty acid methyl esters were studied, and the origin of the unique ion at m/e 75 was established using 18O and 2H labeled analogs and metastable ion transitions. this ion was shown to arise from the loss of ketene from the 3,4 cleavage ion at m/e 117. 相似文献
19.
Aldo Ferretti Vincent P. Flanagan John M. Roman 《Journal of mass spectrometry : JMS》1994,29(7):360-365
The EI mass spectra of six n-butylboronate ester derivatives of the major metabolite of prostaglandins F1α and F2α (PGF-M) are presented and discussed. Proposed ion assignments and fragmentation pathways are based on substituent shifts, on data from a deuterium-labeled methoxime derivative and on the analysis of collision-induced dissociation spectra of selected ions. Fragment ions suitable for identification and quantification of PGF-M in a biological matrix and diagnostically valuable ions for structure recognition are proposed. 相似文献
20.
S. P. Singh R. K. Vaid P. Dinakar Lukhvinder Singh 《Journal of mass spectrometry : JMS》1988,23(2):140-144
The fragmentation of 1-phenyl-, l-(2′-pyridyl)- and 1-(4′-methyl-2′-quinolyl)-4-acetoacetyI-3-methyIpyrazol-5-ols (compounds 1, 2 and 3, respectively) on electron impact has been studied and the major processes interpreted. The common feature in the mass spectra of these compounds is the loss of ketene, acetonyl radical, acetone and two molecules of ketene from the molecular ion. Whereas the ion generated after the last process, which corresponds to 1-substituted-3-methyIpyrazol-5-ols, loses methyl cyanide in the case of 1, similar ions in the case of 2 and 3 lose ?2HO moiety, necessitating an intramolecular hydrogen transfer followed by ring fission and subsequent loss of methyl cyanide. All these and other related processes have been substantiated with the help of accurate mass measurements of the fragment ions and B/E linked-scan spectra. 相似文献