H NMR Data

Integration of spectra is especially important for unknown materials. The presence of six signals, each of which integrates to three protons, indicates that this unknown contains 

Designation Chemical Shift Coupling Constants (Hz) Integration ( H) 

Designation Chemical Shift /i Directly Attached Hydrogen(s) 

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Both and H NMR data are also available for a range of 2(l//)-pyrazinones which are structurally related to the aspergillic acids (76T655). 

The configuration of pairs of isomeric 4-aryIidene-5-pyrazoIones, (Z)- and (E)-(117), was determined by H NMR data (72G491). When R is H, the E configuration is preferred when it is a methyl or a phenyl group, the Z configuration predominates. The presence of an exocyclic sulfur atom as in (118) lowers the interconversion barrier and the products... 

Table 10 Structure and H NMR Data of Seven-membered Heterocyclic Compounds...

H N coupling constants, often measured in H NMR using labeled compounds, are discussed together with N NMR (Section VI,D). Taking into account that H NMR data are now present in every paper dealing explicitly or implicitly with tautomerism, only a few articles are documented in this section. 

H NMR Data of the Ring Hydrogens of Some Nitronaphthyridines and Their 4-AND 5-AmiNO-(J-ADDUCTS AND 4-Methylamino-(J-adducts ... 

As the alkaloid was extracted with hexane, acetone, and ethanol, subjected to column chromatography, acidified (AcOH) and then neutralized (NaOH), the cationic form was formulated as a hydroxide salt. However, only two OH groups were detectable on H NMR spectroscopy. Only slight differences were found in the UV spectra taken in methanol [kmax (loge) = 218 (4.68), 302 (4.39), 394 (4.08) nm] and methanol+NaOH [T-max (loge) = 228 (4.66), 310 (4.39) nm]. Three tautomeric forms can be formulated which are shown in Scheme 42. Two of them possess the isoquinolium-7-olate moiety. The H NMR data are presented in Table IV. They indeed unambiguously resemble the cationic species 112. 

Characteristic H NMR data of (4a/ ,55)- and (4n5,5R)-2-substituted 5- [A-(/e/ /-butoxycarbonyl)-L-tryptophyl]amino perhydropyrido[l,2-c]pyri-midine-l,3-diones were tabulated (01JMC2219). C CPMASS NMR data of 4-(4-methoxyphenyl)perhydropyrido[l,2-c]pyrimidine were reported (00JST73). C NMR data were reported for eight 4-aryl-2,3,5,6,7,8-hexahydro-l//-pyrido[l,2-c]pyrimidin-l,3-diones in the solid state and in CDCI3 solution (00JPO213). The structure of 4-aryl-3,4-dihydro-2//-pyrido [l,2-c]pyrimidine-l,3-diones and their 2,3,5,6,7,8-hexahydro derivatives were characterized by H and C NMR data (99JHC389). Conformational analysis of 6-methyl-2,3,4,6,7,ll/)-hexahydro-l//-pyrimido[6,l-n]isoquino-lin-2-ones 138 and 139 were carried out by H and C NMR studies (97LA1165). 

Propose structures for compounds that fit the following H NMR data ... 

Addition of metalated, enantiomerically pure a-sulfinyl dimethylhydrazones (e.g., 9) to racemic a-chiral aldehydes 10 proceeds with good to excellent diastereo- and enantioselectivi-ty12. Diastereomeric ratios increase with increasing steric demand of the acetaldehyde substituent R1 compared to the methyl group, and each diastereomer is obtained with high enantiomeric excess. In the aldol-lype addition to 2-phenylpropanal, one of the four possible stereoisomers is formed selectively. The relative (syn) and absolute (R.R) configuration is in accord with Cram s and related rules as well as H-NMR data of closely related compounds. 

In the reaction of the strongly electrophilic 4-nitrobenzenediazonium ion with 2-naphthol-6,8-disulfonic acid, which yields a sterically hindered o-complex, Roller and Zollinger (1970) actually observed the rapid formation of a 7T-complex spec-trophotometrically at low pH. The concentration of the 7T-complex decreases slowly and at the same rate as that of the formation of the azo product. H NMR data indicate that the 7t-complex is not localized. All 7T-electrons of the benzene and the naphthalene system are involved in the complex formation to a similar degree, in... 

H NMR data has been reported for the ethylzinc complex, Zn(TPP—NMe)Et, formed from the reaction of free-base N-methyl porphyrin H(TPP—NMe) with ZnEti. The ethyl proton chemical shifts are observed upheld, evidence that the ethyl group is coordinated to zinc near the center of the porphyrin. The complex is stable under N2 in the dark, but decomposed by a radical mechanism in visible light.The complex reacted with hindered phenols (HOAr) when irradiated with visible light to give ethane and the aryloxo complexes Zn(TPP—NMe)OAr. The reaction of Zn(TPP—NMe)Et, a secondary amine (HNEt2) and CO2 gave zinc carbamate complexes, for example Zn(TPP—NMclOiCNEti."" ... 

P = parent ion detected in mass spectrum. Color of complex p-y, pale yellow o, orange o-b, orange-brown c, colorless w, white d-g, deep-green b-g, blue-green r-b, red-brown d-p, dark-purple 1, lemon r, red g, green. H NMR data are available on all the compounds and P NMR on all the Pt-phosphine complexes 231). 

The COSY-45 spectrum of podophyllotoxin and its H-NMR data are shown. Assign and interpret the H/ H cross-peaks in the COSY spectrum. 

The DQF (double-quantum filtered)-COSY spectrum of an isoprenyl coumarin along with H-NMR data are shown. Determine the H/ H homonuclear interactions in the DQF-COSY spectrum. 

While H-NMR data have been published both for betacyanins and for betaxanthins, C data of C14-C15 saturated betacyanins and betaxanthins have only recently become... 

Table 1. H-NMR data (400 Hz, DjO) for the anomeric and C-1 protons in galacturonic acid (GalUA), diGalUA, triGalUA, reduced diGalUA (diGalU-ol), triGalU-ol and pentaGalU-ol. 5 ppm values are centred for doublets and are relative to the D O resonance (4.80 ppm)...

The H-NMR technique has proved to be a valuable tool for structural determinations of tropane alkaloids and their synthetic analogs, and H-NMR data are now available for most of the basic tropane alkaloid structures (42,59,142-146). Recent high-frequency H-NMR data of some basic tropane alkaloids are summarized in Table IV. 

It is interesting that the H-NMR data of the dihydro derivative (34) are practically identical with those of 14/1-hydroxygelsedine (8) which was isolated from G. sempervirens in 1985 (11), although the latter data were, recorded at 360 MHz while the former at 90 MHz in the same solvent (CDC13). Since humantenidine has been proved to be 14-hydroxy-A4,20-gelsedine, it appears that 34 and 8 are the same material. 

The H-NMR data of koumidine are in accord with the proposed structure 12. Furthermore, when koumidine was oxidized with Cr03-H2S04, the product [35, C19H20N2O (M+ 292)] which resulted was a dehydrogenated product of koumidine, and the OH signal disappeared from the H-acetyl... 

Table II presents H-NMR data of the hasubanan alkaloids obtained since 1976. During the period 1976-1986, the application of H-NMR spectroscopy was accelerated together with the improvement of measuring instruments. NOE, INDOR, and two-dimensional NMR experiments (7) have been undertaken to resolve the question of stereochemistry at the chiral centers.

Dihydroepistephamiersine 6-acetate (7) was isolated from Stephania abyssinica as a homogeneous oil. The UV spectrum showed an absorption maximum at 286 nm, and the IR spectrum exhibited a band corresponding to an aliphatic ester carbonyl group at 1725 cm-1 (20). The H-NMR data are summarized in Table II. In chemical investigations, hydrolysis of 7 with barium methoxide gave an alcohol identical with 6-dihydroepistephamiersine (17), which on further treatment with mineral acid gave the known alkaloid, stephasunoline (17). Thus structure 7 was proposed for 6-dihydroepistephamiersine 6-acetate (20). 

A different synthetic access to a 1 -metallacyclopropene, which can be a versatile organometallic synthon, is displayed in Scheme 33. The mono-alkyne derivatives of W(IV)-calix[4]arene are easily accessible through the thermal displacement of cyclohexene from 32 using the appropriate acetylenes. The reaction led to complexes 34 and 172-174. The proposed 3-metallacyclopropene has been confirmed from the spectroscopic and the X-ray data. The H NMR data reveal a cone conformation of the calixarene with a four-fold symmetry, for which the... 

The stereochemistry of each enantiomer separated by the chiral HPLC has been studied after methanolysis of the epoxy ring. Examining the H NMR data of esters of the produced methoxyalcohols with (S)- and (R)-a-methoxy-a-(tri-fluoromethyl) phenylacetic acid by a modified Mosher s method [181], it has been indicated that the earlier eluting parent epoxides are (3S,4R)-, (6S,7R)-, and (9R,10S)-isomers (Table 7) [75, 76, 179]. The above three chiral HPLC columns show different resolution abilities but a different elution order is not observed. The resolution profile by the reversed-phase OJ-R column has been generalized with molecular shapes of the epoxy compounds considering the... 

Cytisine is a tricyclic quinolizidine alkaloid that binds with high affinity and specificity to nicotinic acetylcholine receptors. In principle, this compound can exist in several conformations, but semi-empirical calculations at the AM 1 and PM3 levels have shown that stmctures 19 and 20 are more stable than other possible conformers by more than 50 kcalmol-1. Both structures differ by 3.7 kcalmol 1 at the AMI level and 2.0 kcalmol 1 at the PM3 level, although this difference is much smaller when ab initio calculations are employed <2001PJC1483>. This conclusion is in agreement with infrared (IR) studies and with H NMR data obtained in CDCI3 solution, which are compatible with an exo-endo equilibrium < 1987JP21159>, although in the solid state cytisine has an exo NH proton (stmcture 19) (see Section 12.01.3.4.2). 

On the basis of their 13C NMR assignments (see below), 111—111 correlation spectroscopy (COSY) and H-13C COSY experiments allowed to assign the H NMR data of a series of sparteine analogues and derivatives (compounds 24-27). These data are collected in Table 2 <2003JST275>. Detailed 111 NMR assignments for other sparteine derivatives are also available in the literature (see, for instance, <2005JST75>). 

Substituents may play a crucial role in the conformation of quinolizidine systems. Thus, compound 49 shows a trans-conformation 50 with all three hydroxyl groups in equatorial positions. For its diastereomer 51, a -conformation 52 was initially proposed, but the H NMR data point at the /raor-conformation 53, with axial orientation of the hydroxy substituents and presumably stabilized by an intramolecular hydrogen bond <2004T3009>. 

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