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1.
Summary Direct resolution of four stereoisomers of the related compound of diltiazem hydrochloride, namely desacetyl diltiazem hydrochloride, was studied by both normal and reversed-phase chiral HPLC. The four stereoisomers were completely resolved on a Chiralcel OF column. The technique developed was applied to a chiral inversion study of desacetyl diltiazem hydrochloride. This inversion was observed neither in the solid state, in aqueous solution at 100°C for 3 h nor under visible light for 10h, but was observed in aqueous solution under UV irradiation.The (+)-(2S, 3S)-cis-desacetyl diltiazem hydrochloride degraded with a half-life of 1.9 h in aqueous solution under UV and epimerized to (+)-(2R, 3S)-trans-desacetyl diltiazem hydrochloride. Similarly, (+)-(2S, 3S)-cis-desacetyl diltiazem hydrochloride degraded about three times faster than diltiazem hydrochloride. Reverse epimerization of (+)-(2R, 3S)-trans-desacetyl diltiazem hydrochloride to (+)-(2S, 3S)-cis-desacetyl diltiazem hydrochloride was not observed.The overall degradation was the result of two competitive processes, the epimerization and the decomposition of the benzothiazepin ring. The degradation and epimerization rate of (+)-(2S, 3S)-cis-desacetyl diltiazem hydrochloride in solution under UV depended upon the solvent, the aqueous pH, and concentration.  相似文献   

2.
(+)-cis-Achillene ( 10 ) and (?)-trans-achillenol (7), two monoterpenes recently isolated [1] from the essential oil of Achilleafilipendulina, were synthesized, together with their stereoisomers (?)-(9) and (+)-(8), starting from (S)-(+)-2,6-trans-dimethylocta-1,3, 7-triene ( 1 ). The isomeric ß-hymen thereties ((?)- 3 and (+)-4), often quoted [2] [3] [4] but never isolated, were obtained as intermediates. The mode of synthesis chosen establishesis (R)-chirality for naturally occurring (?)-trans-achillenol (7) and (+)-cis-achillene ( 10 ) as well as for the purely synthetic 4, 7-diene derivatives described in this paper.  相似文献   

3.
An investigation of the conversion of Δ1-3,4-cis-THC 1a to Δ6-3,4-trans-THC 2a with BBr3 is described. By use of 1a of known optical purity it was determined that the main epimerization occurs at C-4. The small loss of optical purity observed during formation of 2a results from either competitive epimerization at C-3 or a racemization process. The conversion of 3,4-cis- to 3,4-trans-HHCs proceeds with exclusive C-4 inversion.  相似文献   

4.
The 6 R configuration of (+)-cis-γ-irone [(+)- 4 ] was established by chemical correlation with (—)-camphor. (+)-cis-γ-irone [(+)- 4 ] was converted into (+)-cis-α-irone [(+)- 1 ], (?)-trans-α-irone [(minus;;)- 2 ], and (+)-β-irone [(+)- 3 ], which therefore also have the 6 R configuration. The 2 S configurations of (+)-cis-α-irone [(+)- 1 ] and (+)-trans-α-irone [(+)- 2 ] were determined by comparison of their circular dichroism with that of R-α-ionone [(+)- 5 ]. The 2 S configuration of (+)-cis-γ-irone [(+)- 4 ] was established by chemical correlation with (+)-cis-α-irone [(+)- 1 ].  相似文献   

5.
Three syntheses of the hitherto unknown (±)-Δ6-3,4-cis-THC 4a and the first total synthesis of optically active Δ1- and Δ6-cis-THC's are described. These syntheses utilize a stereospecific intramolecular epoxide opening by phenolate anion; an acid catalyzed equilibration of Δ1- and Δ6-cis-THC acetates; and a kinetically controlled dehydration. The use of HPLC, GLC and NMR for the separation and identification of closely related THC's is discussed.  相似文献   

6.
The stereo cyclic siloxane compounds having tetra hydroxyl and tetra methyl group were synthesized by hydrolysis of tetrahydrido tetramethyl cyclosiloxane consisting of four stereoisomers. Among the stereo cyclic isomers, cis-trans-cis tetrahydroxyl tetramethyl cyclosiloxane (2) was separated by recrystallization and was used as a monomer species for preparation of ladder-like polymethylsilsesquioxane (PMSQ). The isolated isomer was directly polymerized in THF with potassium carbonate (K2CO3) by systematic ring condensation. The hydrolyzed stereoisomers were characterized by 1H and 29Si NMR, and HPLC. The structure of the synthesized PMSQs were characterized by size exclusion chromatography (SEC), MALDI-TOF mass, 29Si NMR, and small angle X-ray scattering (SAXS).  相似文献   

7.
α-, β-, and γ-Irones and analogues have been prepared from optically active ketones (+)- 1 , (+)- 6a,b , and (+)- 17 , via a Corey-Chaykovsky oxiranylation (Me2S, Me2SO4, Me2SO, NaOH) followed by isomerisation (SnCl4 or MgBr2). (+)-Dihydrocyclocitral ( 19a ), obtained from (?)-citronellal, and analogue (+)- 19b , were condensed with various ketones to afford (+)- 21a–f , and after hydrogenation (+)- 22a–f. A mild oxidative degradation of aldehydes (+)-trans-and (?)-cis- 8a,b , to ketones (?)- 16a,b , as well as olfactive evaluations, 13C-NMR assignments, and absolute configurations of the intermediate epoxides, aldehydes, and alcohols are presented.  相似文献   

8.
The optimal geometry of isomeric molecules of (XP-CCl2)2 with X = F, Cl, Br was determined by RHF/6-31G(d) calculations. With X = F and Cl, the electronic correlation was considered on the MP2/6-31G(d) level. The P2C2 ring is nonplanar. With X = Cl and Br, the trans conformation is energetically preferable compared to the two possible cis conformations: by 7.8 and 14.2 kJ mol- 1 for X = Cl and by 7.5 and 14.1 kJ mol- 1 with X = Br. respectively. With X = F, the calculated energies of the cis and trans forms are very close.  相似文献   

9.
The preparation of (−)- and (+)-trans-α-irone ( 1a and 1b , resp.) and of (+)- and (−)-cis-α-irone ( 1c and 1d , resp.) from commercially available Irone alpha ® is reported. The relevant step in the synthetic sequence is the initial chromatographic separation of crystalline (±)-4,5-epoxy-4,5-dihydro-cis-α-irone ((±)- 5 ) from oily (±)-4,5-epoxy-4,5-dihydro-trans-α-irone ((±)- 4 ). The latter was subsequently converted, after NaBH4 reduction, into the crystalline 3,5-dinitrobenzoate ester (±)- 8 , thus allowing a complete separation of the two corresponding diastereoisomeric alcohol derivatives. Suitable enantiomerically pure precursors of the desired products 1a – d were obtained by kinetic resolution of the racemic allylic alcohols derived from (±)- 5 and (±)- 8 , mediated by lipase PS (Amano). The last steps consisted of MnO2 oxidation and removal of the epoxy moiety with Me3SiCl/NaI in MeCN. External panel olfactory evaluation showed that (−)-cis-α-irone ( 1d ) has the finest and most distinct `orris butter' character.  相似文献   

10.
Abstract

The vCO IR analysis of α-(p-phenylsulfinyl)-p-substituted acetophenones X-φC(O)CH2S(O)φ-Y 1–8, being X and Y = NO2, H and OMe substituents, supported by ab initio calculations of the α-methylsulfinyl/acetophenone (model compound) along with the X-ray geometrical data for 1,7 and 8, indicates the existence of the cis 2 and gauche rotamers for compounds 1-4 and 6. Compounds 5,7 and 8 present another less stable and more polar cis 1 rotamer. The cis 2 rotamer concentration for 4 (ca. 97% in CCl4) is reduced to ca. 50% for 2,3,5-7 and to ca. 20% for 1 and 8. This behavior is discussed in terms of Oδ- (CO—Sδ+ (SO) charge transfer and Coulombic interactions, which stabilize the cis 1 rotamer, and the π*COC-S, πCO/ns and π*COC-S orbital interactions, which stabilize the gauche rotamers. The progressive more negative carbonyl cis 2 shifts (Δvc), when X varies from NO2 to H and to OMe for the same Y, along with the unexpected NAE values of the α-methylene carbon chemical shifts for compounds 1–8 give further support for the existence of a strong intramolecular complex betwen C=O and S=O dipoles which stabilizes the cis 2 rotamer. The progressive more negative carbonyl gauche shifts (Δvg), when X varies from NO2 to H and to OMe for the same Y, is in line with the higher contibution of the interaction πCO/δ*C-S, which stabilizes the gauche rotamer of the title compounds.  相似文献   

11.
Absolute configuration of the 3,5-diaminohexanoic acid produced in the β-lysine mutase reaction The (3S, 5S)-configuration of the 3,5-diaminohexanoic acid 3 produced by the coenzyme-B12-dependent β-lysine mutase from Clostridium sticklandii has been determined by two different methods: by comparison of the 1H-NMR.-spectrum of its δ-lactam with that of synthetic (±)-cis-and (±)-trans-4-amino-6-methyl-piperidones ( 1 and 2 ) and by chemical correlation with (+)-(6S)-6-methyl-piperidone-2 ( 9 ).  相似文献   

12.
The acid-catalysed intramolecular nucleophilic addition of the phenyl ring to the C(9a) = N(1) double bond of ethyl 9-(N-methyl-N-phenyl)-4-oxotetrahydro-4H-pyrido[1,2-a]pyrimidine-3-carboxylates, formed in the reactions of ethyl 9-bromo-4-oxo-6,7,8,9-tetrahydro-4H-pyrido[1,2-a]pyrimidine-3-carboxylates and N-methylaniline, gave the first examples of a new tetracyclic pyrimido[1′,2′:1,2]pyrido[3,2-b]indole ring system ( 7 ). X-ray diffraction analysis of 7a revealed that the annelation of the pyrimidine and piperidine rings is transoid, while that of the piperidine and pyrroline rings is cis, the piperidine ring adopts an unusual 6T8 twisted boat conformation, while the pyrroline ring has a 9T8a conformation.  相似文献   

13.
Incubation of (?)-Δ1-3, 4-trans-tetrahydrocannabinol (= Δ1-THC; 3 ) with stationary cultures of Cunninghamella blakesleeana LENDER (Zygomycetales) (ATCC 8688a) yielded a number of metabolic conversion products. Isolation and structure elucidation of 6α-hydroxy-Δ1-THC ( 4 ), the potential psychoactive 3″-hydroxy-Δ1-THC ( 2 ) and 4″-hydroxy-Δ1-THC ( 1 ), and the hitherto unknown metabolites 4″-hydroxy-6-oxo-Δ1-THC ( 5 ), 4″, 6α-dihydroxy-Δ1-THC ( 7 ) and 4″, 7 -dihydroxy-Δ1-THC ( 6 ) is described.  相似文献   

14.
Epoxidation of (?)-(1R,2R,4R)-2-endo-cyano-7-oxabicyclo[2.2.1]hept-5-en-2-exo-yl acetate ((?)-5) followed by saponification afforded (+)-(1R,4R,5R,6R)-5,6-exo-epoxy-7-oxabicyclo[2.2.1]heptan-2-one ((+)-7). Reduction of (+)-7 with diisobutylaluminium hydride (DIBAH) gave (+)-1,3:2,5-dianhydroviburnitol ( = (+)-(1R,2R,3S,4R,6S)-4,7-dioxatricyclo[3.2.1.03,6]octan-2-ol; (+)-3). Hydride reductions of (±)-7 were less exo-face selective than reductions of bicyclo[2.2.1]heptan-2-one and its derivatives with NaBH4, AlH3, and LiAlH4 probably because of smaller steric hindrance to endo-face hydride attack when C(5) and C(6) of the bicyclo-[2.2.1]heptan-2-one are part of an exo oxirane ring.  相似文献   

15.
The 13C NMR spectra of the isomeric alkaloids lupinine and epilupinine and their perchlorates, methiodides and N-oxides are discussed. Chemical shift changes due to protonation, quaternization and N-oxidation are analysed. The trans-quinolizidine ring fusion is proved for epilupinine salts and for the N-oxide. Lupinine also exists predominantly with the trans ring fusion, but the cis ring fusion is found in the methiodide. An equilibrium of two stereoisomers, one with trans- and the other with cis-ring fusion, has been established for lupinine perchlorate in D2O solution. Lupinine N-oxides isolated in the crystalline state are shown to have both trans- and the cis-ring fusion.  相似文献   

16.
Structure and properties of 5-epi-flavoxanthin and 5-epi-chrysanthemaxanthin The absolute configurations of 5-epi-flavoxanthin ( 6 ) and 5-epi-chrysanthemaxanthin ( 7 ) prepared by acid catalysed rearrangement of semi-synthetic lutein epoxide 5 are shown to be (3S, 5S, 8R, 3′R, 6′R) and (3S, 5S, 8S, 3′R, 6′R), respectively. Contrary to published data [5] the relationship of the polyene chain and H3(18) on the dihydrofurane ring is cis for the pair of stereoisomers having a Δδ = δ (H? C(7)) ? δ (H? C(8)) = 0,22 ppm and 3J ≡ 0. These conclusions are in full accord with the chiroptical data.  相似文献   

17.
Abstract

The decarboxylation reaction of δ -cis-β-[Co(L1)(pdH)]2+ complex yielded δ -cis-β-[Co(L1) (R-pro)]2+, while the δ -cis-β-[Co(L2) (S-pro)]2+ was obtained from the reaction of δ -cis-β-[Co(L2) (pdH)]2+, where L1 is (3R)3-methyl-1, 6-bis[(2S)-pyrrolidin-2-yl]-2, 5-diazahexane, L2 is (3S) 3-methyl-1, 6-bis-[(2S)-pyrrolidin-2-yl]-2, 5-diazahexane, and pdH is the pyrrolidine-2, 2-dicarboxylate ion. The asymmetrically synthesized prolines were isolated via the decomposition of the decarboxylated complexes. The proline isolated from δ -cis-β-[Co(L1) (R-pro)]2+ showed a specific rotation of +12.0, representing a 24% excess of R-proline over S-proline, while the proline isolated from δ -cis-β-[Co(L2) (S-pro)]2+ showed a specific rotation of -10.0, indicating a 20% excess of S-proline over R-proline.  相似文献   

18.
Following the intraperitoneal administration of high doses of 14C- and 3H- labelled retinoic acid (1) to rats, three major metabolites and the intact compound were isolated from the feces in microgram amounts by use of column, thin-layer and high-pressure liquid chromatography. Their structures were elucidated by mass spectrometry and Fourier Transform 1H-NMR. spectroscopy as 2 (all-trans-4-oxoretinoic acid), 3 (7-trans-9-cis-11-trans-13-trans-5′-hydroxy-retinoic acid). Hydroxylation of the 5-methyl group of the cyclohexene ring, oxidation of the cyclohexene ring in position 4 and cis-trans isomerisation of the nonatetraenoic acid side chain were the reactions, which produced these products from retinoic acid. The metabolites 2 and 4 each accounted for about 4% of the radioactivity administered. The metabolite 3 and the parent compound accounted for about 16% and 17% of the dose, respectively.  相似文献   

19.
The absolute configuration of (+)-α-ionone 3 (R), the absolute configurations at C(6) of (+)-cis-α-irone 5 (6S) and (?)-trans-α-irone 6 (6R), and the absolute configurations of (+)-cis-abscisic acid 10 (S) and (+)-trans-abscisic acid 11 (S) are deduced from the CD.-spectra.  相似文献   

20.
The indolic analogs of (1R)-cis-chrysanthemic acid and N-substituted (1R)-cis-chrysanthemylamines were obtained by Fischer indole synthesis using the acetonylcyclopropanes derived from (+)-car-3-ene. The cyano- and N-cyanamido groups in the starting carbonyl compounds did not hinder indolization. The reduction of the nitrile group bound to the asymmetrical atom of the cyclopropane ring by LiAlH4 in ether can be accompanied by epimerization or racemization.  相似文献   

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