脯氨酸类N-酰胺衍生物的核磁共振研究

脯氨酸类衍生物结构独特,鲜有报道利用核磁共振（nuclear magnetic resonance,NMR）技术对氨基酸的手性进行鉴别.利用多种NMR技术:1H NMR、1H-1H同核位移相关谱（1H-1H COSY）、1H-1H质子全相关谱（1H-1H TOCSY）、1H-1H核Overhauser效应谱（1H-1H NOESY）、13C NMR、无畸变的极化转移增强法（DEPT135°）、1H-13C检出1H的异核单量子相干（1H-13C HSQC）和1H-13C检出1H的异核多键相关（1H-13C HMBC）,对脯氨酸类N-酰胺衍生物两种构象异构体的1H和13C NMR进行了全归属,确定了室温下在二甲基亚砜（DMSO）中L型和D型的顺反异构体以相同的比例同时存在.     

1H, 13C,and 15N NMR spectra of some pyridazine derivatives

¹H, ¹³C, and ¹⁵N NMR chemical shifts for pyridazines 4–22 were measured using 1D and 2D NMR spectroscopic methods including ¹H? ¹H gDQCOSY, ¹H? ¹³C gHMQC, ¹H? ¹³C gHMBC, and ¹H? ¹⁵N CIGAR–HMBC experiments. Copyright © 2010 John Wiley & Sons, Ltd.     

Complete assignments of the 1H and 13C NMR spectra of 15 limonoids

Unambiguous and complete assignments of ¹H and ¹³C NMR chemical shifts for 15 limonoids, eight of them found in natural sources and seven other synthetic derivatives, are presented. The assignments are based on 2D shift‐correlated [¹H,¹H‐COSY, ¹H,¹³C‐gHSQC‐¹J(C,H), ¹H,¹³C‐gHMBC‐ⁿJ(C,H) (n = 2 and 3)] and NOE experiments. Copyright © 2003 John Wiley & Sons, Ltd.     

A NMR method for the analysis of mixtures of alkanes with different deuterium substitutions

¹³C NMR at 125.76 MHz with ¹H and ²H decoupling, ²H NMR at 76.77 MHz with ¹H decoupling, and ¹H NMR at 500.14 MHz with ²H decoupling were employed as analytical tools to study the complex mixtures of deuterated ethanes resulting from the catalytic H–D exchange of normal ethane with gas-phase deuterium in the presence of a platinum foil. Reference samples consisting of 1:1 binary mixtures of pure normal ethane and ethane-d_n (n=1–6) were used to identify the peak positions in the ¹³C, ²H, and ¹H NMR spectra due to each individual isotopomer, and the effect of isotopic substitution on the chemical shifts was determined in each case. While the NMR of all three nuclei worked well for the identification of the individual components of the 1:1 standard mixtures, both ¹H and ²H NMR suffered from inadequate resolution when studying complex reaction mixtures because of the broadening of the lines due to ¹H–¹H (¹H NMR) and ²H–²H (²H NMR) couplings. ¹³C NMR was therefore determined to be the method of choice for the quantitative analysis of the reaction mixtures. Using the ¹³C NMR results, a correlation that takes into account the primary and secondary isotope substitution effects on chemical shifts was deduced. This equation was used for the identification of the individual components of the mixtures, and integration of the individual observed resonances was then employed for quantification of their composition. This study shows that ¹³C NMR with ¹H and ²H decoupling is a viable procedure for studying mixtures of deuterated ethanes. Furthermore, the additivity of the isotopic effects on chemical shifts and the transferability of the values obtained with ethane to other molecules makes this approach general for the analysis of other isotopomer mixtures.     

1H, 13C and 15N NMR chemical shifts of substituted pyrazolo[1,5‐a]pyrimidines

¹H, ¹³C and ¹⁵N NMR chemical shifts of 10 substituted pyrazolo[1,5‐a]pyrimidines were assigned based on DQF ¹H, ¹H COSY, PFG ¹H, ¹³C HMQC and PFG ¹H,X (X = ¹³C and ¹⁵N) HMBC experiments and on literature data. Copyright © 2002 John Wiley & Sons, Ltd.     

New Class of Hydrido Iron(II) Compounds with cis‐Reactive Sites: Combination of Iron and Diphosphinodithio Ligand

The cationic complex [Fe(P₂S₂)(NCMe)₂]²⁺ (P₂S₂=(Ph₂PC₆H₄CH₂S)₂(C₂H₄) ([ 1 (NCMe)₂]²⁺)), with two MeCN ligands in a cis orientation, was synthesized and characterized. The MeCN ligand in [ 1 (NCMe)₂]²⁺ undergoes further substitution by a hydride ligand or CO to give iron(II) hydrides [H 1 (NCMe)]⁺, [H 1 H]⁰, and [H 1 (CO)]⁺. The order of reactivity of the hydrides was [H 1 H]⁰>[H 1 (NCMe)]⁺>[H 1 (CO)]⁺, and was illustrated by their reactions toward protic acids, the organic cation of 10‐methylacridinium (MeAcr⁺) as a hydride acceptor, and intermolecular hydride transfer reactions among these ferrous compounds. For example, MeAcr⁺ was reduced initially by a one‐electron transfer process from [H 1 H]⁰, resulting in competing reactions of MeAcr^. dimerization, hydrogen atom transfer from [H 1 H]⁺ to MeAcr^., and decomposition of [H 1 H]⁺. MeAcrH was produced in excellent yields through a single‐step H^? transfer from [H 1 (NCMe)]⁺ to MeAcr⁺, but [H 1 (CO)]⁺ was inactive toward MeAcr⁺.     

Complete assignment of NMR data of 22 phenyl‐1H‐pyrazoles' derivatives

Complete assignment of ¹H and ¹³C NMR chemical shifts and J(¹H/¹H and ¹H/¹⁹F) coupling constants for 22 1‐phenyl‐1H‐pyrazoles' derivates were performed using the concerted application of ¹H 1D and ¹H, ¹³C 2D gs‐HSQC and gs‐HMBC experiments. All 1‐phenyl‐1H‐pyrazoles' derivatives were synthesized as described by Finar and co‐workers. The formylated 1‐phenyl‐1H‐pyrazoles' derivatives were performed under Duff's conditions. Copyright © 2011 John Wiley & Sons, Ltd.     

Enzymatic synthesis of tryptamine and its halogen derivatives selectively labeled with hydrogen isotopes

Nine isotopomers of tryptamine and its halogen derivatives, labeled with deuterium, tritium in side chain, i.e., [(1R)-²H]-, [(1R)-³H]-, 5-F-[(1R)-²H]-, 5-F-[(1R)-³H]-, 5-Br-[(1R)-²H]-, double labeled [(1R)-²H/³H]-, 5-F-[(1R)-²H/³H]-, and ring labeled [4-²H]-, and [5-²H]-tryptamine, were obtained by enzymatic decarboxylation of l-Trp and its appropriate derivatives in deuteriated or tritiated media, respectively. Intermediates: [5′-²H]-l-Trp used for further decarboxylation was synthesized by enzymatic coupling of [5-²H]-indole with S-methyl-l-cysteine, and [4′-²H]-l-Trp was obtained by isotope exchange ¹H/²H of the authentic l-Trp dissolved in heavy water induced by UV-irradiation. Doubly labeled [(1R)-²H/³H]- and 5-F-[(1R)-²H/³H]-tryptamine were obtain by decarboxylation of l-Trp or [5′-F]-l-Trp carried out in ²H³HO incubation medium.     

盐酸莫西沙星的结构分析研究

报道了盐酸莫西沙星的元素分析、红外光谱(IR) 、紫外光谱(UV) 、质谱(MS) 、氢-氢相关谱(1H-1HCOSY) 、碳谱(DEPT-45、DEPT-90、DEPT-135) 、多键碳氢相关谱(HMBC)等波谱数据,并对特征数据进行了化合物的结构解析。对所有的1H-NMR、13C-NMR谱的信号进行了归属。     

Complete 1H NMR spectral analysis of ten chemical markers of Ginkgo biloba

The complete and unambiguous ¹H NMR assignments of ten marker constituents of Ginkgo biloba are described. The comprehensive ¹H NMR profiles (fingerprints) of ginkgolide A, ginkgolide B, ginkgolide C, ginkgolide J, bilobalide, quercetin, kaempferol, isorhamnetin, isoquercetin, and rutin in DMSO‐d₆ were obtained through the examination of 1D ¹H NMR and 2D ¹H,¹H‐COSY data, in combination with ¹H iterative full spin analysis (HiFSA). The computational analysis of discrete spin systems allowed a detailed characterization of all the ¹H NMR signals in terms of chemical shifts (δ_H) and spin‐spin coupling constants (J_HH), regardless of signal overlap and higher order coupling effects. The capability of the HiFSA‐generated ¹H fingerprints to reproduce experimental ¹H NMR spectra at different field strengths was also evaluated. As a result of this analysis, a revised set of ¹H NMR parameters for all ten phytoconstituents was assembled. Furthermore, precise ¹H NMR assignments of the sugar moieties of isoquercetin and rutin are reported for the first time. Copyright © 2012 John Wiley & Sons, Ltd.     

Two-dimensional NMR studies of cyperene

Combined utilization of ¹H? ¹H homonuclear and ¹H? ¹³C heteronuclear NMR chemical shift correlations, two-dimensional J-resolved ¹H NMR measurements and homonuclear ¹H double resonance experiments allowed specific assignments for both ¹H and ¹³C NMR frequencies to be made for the tricyclic sesquiterpene cyperene. The results also provided information on the conformation of the six-membered ring of this natural product, which was recognized as a distorted chair.     

1H and 13C NMR spectral assignments of some natural abietane diterpenoids

An NMR study of 11 naturally occurring abietane diterpenoids is described. In addition to one‐dimensional NMR methods, including DPFGSE 1D‐NOE spectra, two‐dimensional shift‐correlated experiments [¹H,¹H COSY, ¹H,¹³C‐gHSQC ¹J(C,H) and ¹H,¹³C‐gHMBC ⁿJ(C,H) (n = 2 and 3)] were used for the complete and unambiguous ¹H and ¹³C chemical shift assignments of these substances. Copyright © 2003 John Wiley & Sons, Ltd.     

Derivatives of pyrazinecarboxylic acid: 1H, 13C and 15N NMR spectroscopic investigations

NMR spectroscopic studies are undertaken with derivatives of 2‐pyrazinecarboxylic acid. Complete and unambiguous assignment of chemical shifts (¹H, ¹³C, ¹⁵N) and coupling constants (¹H,¹H; ¹³C,¹H; ¹⁵N,¹H) is achieved by combined application of various 1D and 2D NMR spectroscopic techniques. Unequivocal mapping of ¹³C,¹H spin coupling constants is accomplished by 2D (δ,J) long‐range INEPT spectra with selective excitation. Phenomena such as the tautomerism of 3‐hydroxy‐2‐pyrazinecarboxylic acid are discussed. Copyright © 2009 John Wiley & Sons, Ltd.     

Reactions of β-keto thioamides with α,β-unsaturated aldehydes. Synthesis of 6-hydroxypiperidine-2-thiones and 6H-thiopyrans

Mixtures of 3-benzoylated and 3-unsubstituted 6-hydroxypiperidine-2-thione derivatives were formed in the reaction of benzoyl(acetyl) thioacetamides with α,β-unsaturated aldehydes in refluxing ethanol in the presence of catalytic amounts of triethylamine. A mechanism for the debenzoylation was proposed. Derivatives of 6H-thiopyran were obtained when an analogous reaction was carried out in refluxing pyridine. The structures of all compounds were determined with the aid of 1D NMR (¹H, ¹³C, ¹³C-DEPT-135) and 2D NMR (¹H, ¹H COSY, ¹H, ¹H NOESY, ¹³C, ¹H COSY) spectroscopy.     

Unprecedented Reaction Pathway of Sterically Crowded Calcium Complexes: Sequential C−N Bond Cleavage Reactions Induced by C−H Bond Activations

Five bis(quinolylmethyl)‐(1H ‐indolylmethyl)amine (BQIA) compounds, that is, {(quinol‐8‐yl‐CH₂)₂NCH₂(3‐Br‐1H ‐indol‐2‐yl)} ( L¹H ) and {[(8‐R³‐quinol‐2‐yl)CH₂]₂NCH(R²)[3‐R¹‐1H ‐indol‐2‐yl]} ( L^2–5H ) ( L²H : R¹=Br, R²=H, R³=H; L³H : R¹=Br, R²=H, R³=i Pr; L⁴H : R¹=H, R²=CH₃, R³=i Pr; L⁵H : R¹=H, R²=n Bu, R³=i Pr) were synthesized and used to prepare calcium complexes. The reactions of L^1–5H with silylamido calcium precursors (Ca[N(SiMe₂R)₂]₂(THF)₂, R=Me or H) at room temperature gave heteroleptic products ( L^{1, 2} )CaN(SiMe₃)₂ ( 1 , 2 ), ( L^{3, 4} )CaN(SiHMe₂)₂ ( 3 a , 4 a ) and homoleptic complexes ( L^{3, 5} )₂Ca ( D3 , D5 ). NMR and X‐ray analyses proved that these calcium complexes were stabilized through Ca⋅⋅⋅C−Si, Ca⋅⋅⋅H−Si or Ca⋅⋅⋅H−C agostic interactions. Unexpectedly, calcium complexes (( L^3–5 )CaN(SiMe₃)₂) bearing more sterically encumbered ligands of the same type were extremely unstable and underwent C−N bond cleavage processes as a consequence of intramolecular C−H bond activation, leading to the exclusive formation of (E )‐1,2‐bis(8‐isopropylquinol‐2‐yl)ethane.     

Complete assignments of the 1H and 13C NMR spectra of five rearranged abietane diterpenoids

An NMR study of five highly functionalized and rearranged abietane diterpenoids is described. In addition to 1D NMR methods, including 1D NOESY spectra, 2D shift‐correlated experiments [¹H, ¹³C‐gHSQC‐¹J (C,H) and ¹H, ¹³C‐gHMBC‐ⁿJ (C,H) (n = 2 and 3)] were used for the complete and unambiguous ¹H and ¹³C chemical shift assignments of these substances. Copyright © 2002 John Wiley & Sons, Ltd.     

Triterpenoidal Secondary Metabolites from Lantana Camara Linn.

Three new pentacyclic triterpenoids, camarin ( 1 ), lantacin ( 2 ), and camarinin ( 3 ) were isolated from the aerial parts of Lantana camara Linn ., together with seven known compounds. The structures of the new constituents were elucidated by chemical transformation, HR‐EI mass spectrometry, and NMR spectroscopy, including 1D (¹H‐ and ¹³C‐NMR) and 2D (¹H,¹H‐COSY, NOESY, ¹H,¹H‐TOCSY, J‐resolved, HMQC, and HMBC) experiments.     

Structure elucidation of [1,3]oxazolo[4,5‐e][2,1]benzisoxazole and naphtho[1,2‐d][1,3]‐ and phenanthro[9,10‐d]oxazoles using gradient selected gHMBC,gHMQC and gHMQC‐TOCSY NMR techniques

Structure elucidation of compounds in the benzisoxazole series ( 1 – 6 ) and naphtho[1,2‐d][1,3]‐ ( 7 – 10 ) and phenanthro[9,10‐d][1,3]oxazole ( 11 – 14 ) series was accomplished using extensive 2D NMR spectroscopic studies including ¹H–¹H COSY, long‐ range ¹H–¹H COSY, ¹H–¹³C COSY, gHMQC, gHMBC and gHMQC‐TOCSY experiments. The distinction between oxazole and isoxazole rings was made on the basis of the magnitude of heteronuclear one‐bond ¹J_{C2, H2} (or ¹J_{C3, H3}) coupling constants. Complete analysis of the ¹H NMR spectra of 11 – 14 was achieved by iterative calculations. Gradient selected gHMQC‐TOCSY spectra of phenanthro[9,10‐d][1,3]oxazoles 11 – 14 were obtained at different mixing times (12, 24, 36, 48 and 80 ms) to identify the spin system where the protons of phenanthrene ring at H‐5, H‐6 and at H‐9 and H‐7 and H‐8 were highly overlapping. Copyright © 2003 John Wiley & Sons, Ltd.     

Interpretation dü spectre RMN-3H du PK-11195 (3H)

(1D-³H NMR) of PK 11195 ³H gives a complex spectrum. Homonuclear 2D-³H NMR (COSY and J. Resolved) gives useful information such as tritium chemical shifts, ³H-³H and ³H-¹H coupling constant, percentage of isotopomers and specific activity.