Complete 1H and 13C data assignments of two new guaianolides isolated from Ainsliaea fragrans

Two new guaianolides, 8alpha-hydroxy-11alpha,13-dihydroglucozaluzanin C and 11alpha,13-dihydroglucozaluzanin C, were isolated from Ainsliaea fragrans, along with two known guaianolides, 8alpha-hydroxy-11alpha,13-dihydrozaluzanin C and glucozaluzanin C. The structures of the new compounds were unambiguously established by HR-ESI-MS, one-dimensional (1D) (DEPT), two-dimensional (2D) ((1)H-(1)H COSY, HSQC, HMBC, ROESY) NMR experiments and by comparison with structurally related compounds. The known compounds were identified by comparison of spectral data with published references. Some NMR data of the known compounds were reported for the first time.     

Complete 1H and 13C assignments of some epipodophyllotoxin derivatives

The complete analyses of the ¹H and ¹³C NMR spectra of the ortho ester analogues of etoposide are reported and differentiation of the α and β isomers of these derivatives is suggested by using the γ‐gauche effect upon the ¹³C chemical shift. Copyright © 2003 John Wiley & Sons, Ltd.     

Two isomeric epoxysitosterols from Rhododendron formosanum: 1H and 13C NMR chemical shift assignments

1H and 13C NMR assignments of the two isomeric epoxysitosterols, 5,6 alpha-epoxy-5 alpha-stigmastan-3 beta-ol (1) and 5,6 beta-epoxy-5 beta-stigmastan-3 beta-ol (2), isolated from the leaves of Rhododendron formosanum Hemsl were achieved by 1D and 2D techniques such as DEPT, HMBC, HMQC, COSY and NOESY.     

1H and 13C assignments of two new triterpenes from Cladocolea grahami

The structure elucidation and 1H and 13C assignments of the new triterpenes 3beta-palmitoxy-7beta-hydroxyolean-12-ene (1) and its hydrolysis product 3beta,7beta-dihydroxyolean-12-ene (2) and 3beta-sn-glyceroyl-(1'-palmitoxy)urs-12-ene (3), isolated from the aerial parts of Cladocolea grahami (Loranthaceae), are reported.     

1H and 13C NMR spectral assignment of androstane derivatives

(1)H and (13)C NMR spectroscopic data for 5alpha-androstanes and halo-5alpha-androstanes with different substituents at positions C-3, C-9, C-11 and C-17 were examined and assigned by a combination of 1D and 2D NMR experiments. The substituent effects on the (13)C chemical shifts were compared with those of epi-androsterone, used as a reference compound. The coupling constants (n)J((19)F,(13)C) were measured for compounds 6, 8, 11 and 14.     

Complete assignments 1H and 13C NMR spectral data of four anabaseine derivatives

The anabaseine derivatives 6-methoxy-7-hydroxy-1-(pyridin-3-yl)-3,4-dihydroisoquinoline, 6,7-dimethoxy-1-(pyridin-3-yl)-1,2,3,4-tetrahydroisoquinoline and 6,7-dimethoxy-1-(piperidin-3-yl)-1,2,3,4-tetrahydroisoquino- line were prepared either by demethylation with HBr or by reduction with different reagents, NaBH4 and H2/PtO2 from 6,7-dimethoxy-1-(pyridin-3-yl)-3,4-dihydroisoquinoline, as starting material. The structures have been fully assigned by the combination of one- and two-dimensional experiments.     

Complete assignments of 1H and 13C NMR data for ten phenylpiperazine derivatives

Ten phenylpiperazine derivatives were designed and synthesized. The first complete assignments of (1)H and (13)C NMR chemical shifts for these phenylpiperazine derivatives were achieved by means of 1D and 2D NMR techniques, including (1)H-(1)H COSY, HSQC and HMBC spectra.     

Complete assignments of (1)H and (13)C NMR data for two 3beta,8beta-epoxymexicanolides from the fruit of a Chinese mangrove Xylocarpus granatum

Three 3beta,8beta-epoxymexicanolides, including xyloccensin K, 6-acetoxycedrodorin and a new one named xyloccensin W, were isolated from the fruit of a Chinese mangrove Xylocarpus granatum. Their structures were determined by spectroscopic analyses. The first complete assignment of (1)H and (13)C NMR data for xyloccensin W was achieved by means of 2D NMR techniques, including (1)H-(1)H COSY, HSQC, HMBC and NOESY spectra. In addition, the confusion of (1)H and (13)C NMR data previously reported for xyloccensin K was clarified.     

Complete assignments of 1H and 13C NMR data for trypanocidal eremantholide C oxide derivatives

The chemical transformations of eremantholide C (1), a trypanocidal sesquiterpene lactone isolated from Lychnophora trichocarpha Spreng., gave five new oxide derivatives: 3'-hydroxyeremantholide C (2), 1'-formyleremantholide C (3), 1'-carboxyeremantholide C (4), 1'-carbomethoxyeremantholide C (5) and sodium 1'-carboxylate of eremantholide C (6). The (1)H and (13)C NMR data of all these derivatives were assigned based on 1D and 2D techniques. The derivatives were evaluated against Y and CL strains of Trypanosoma cruzi. All of them were inactive against the Y strain. Compounds 2 and 5 displayed 100% activity on the CL strain while compounds 4 and 6 were partially active on the CL strain.     

Complete (1)H and (13)C NMR spectral assignment of alpha- and beta-adenosine, 2'-deoxyadenosine and their acetate derivatives

(1)H and (13)C NMR chemical shifts of alpha- and beta-anomers of adenosine, 2'-deoxyadenosine and their acetate derivatives were completely and definitely assigned using the concerted application of one- and two-dimensional experiments (gCOSY, gNOESY, gHSQC and gHMBC). The influence of the stereochemistry of the purine base on the NMR data of the hydrogen and carbon atoms of the furanose moiety was estimated.     

Preparation of alpha-diazocarbonyl compounds from beta-lapachone derivatives and other 1,2-naphthoquinones: use of the 2D NMR 1H,15N and 1H,13C HMBC techniques in assigning regiochemistry

The assignment of the diazo site in products of the reaction of p-toluenesulfonylhydrazine with beta-lapachone, 3,4-dihydro-2,2-dimethyl-2H-naphtho[1,2-b]pyran-5,6-dione, and other 1,2-naphthoquinones in methanol solution at room temperature has been accomplished using 1H,13C HMBC and 1H,15N HMBC NMR experiments. Only one diazo-naphthalenone product was isolated in yields ranging from 50-100% from each reaction. The site of diazo substitution of beta-lapachone and derivatives is the 1-position, in contrast to substitution at the 2-position in 4-MeO-1,2-naphthoquinone. Steric factors, rather than electronic factors, control the reaction site. Along with 2-diazo-1(2H)-naphthalenone, an additional product isolated from the reaction of p-toluenesulfonylhydrazide with 1,2-naphthoquinone was 2-diazo-4-hydroxy-1(2H)-naphthalenone. Confirmation of the formation of 6-diazo-2,2-dimethyl-2,3,4,6-tetrahydro-2H-benzo[h]cromen-5-one, obtained from beta-lapachone, was achieved using single crystal X-ray diffraction.     

Complete 13C NMR assignments for ent-kaurane diterpenoids from Sideritis species

In this work, the detailed NMR studies and full (13)C NMR assignments for five diterpenoids isolated from Sideritis caesarea and Sideritis athoa are described. The assignments are based on a combination of 1D and 2D NMR techniques including (1)H, (13)C, (1)H-(1)H COSY, gHSQC [(1)J(C,H)] and gHMBCδ(C) [(n)J(C,H)(n=2 and 3)] and NOESY experiments.     

1H, 13C and 15N NMR spectral assignments for new triazapentalene derivatives

Mesomeric heteropentalene betaines are conjugated fused polyheterocyclic structures that represent interesting intermediates for organic synthesis. Five such structures, containing at least four nitrogen atoms and various substituents, have been characterized by ¹H, ¹³C and ¹⁵N NMR. We report, apparently for the first time, nitrogen NMR data and coupling information on such systems. Inter‐ring long‐range correlations across five bonds with ¹⁵N (⁵J_HN) and up to seven bonds with ¹³C (⁶J_HC and ⁷J_HC) were observed in HSQC experiments. The incorporation of an electron‐withdrawing substituent such as NO₂ was observed to cause an increase in the magnitude of the remote couplings and deshielding of nearby protons, carbons and on all nitrogen atoms of the structure, including remote ones situated on other cycles. Copyright © 2009 John Wiley & Sons, Ltd.     

Complete 1H and 13C NMR assignments and Z/E-stereoconfiguration determination of isomers of 1,4-diketone derivatives

Complete 1H and 13C NMR assignments and Z/E-stereoconfiguration determination for a series of new isomers of 1,4-diketone derivatives obtained via self-sorting tandem reaction were accomplished by means of one- and two-dimentional NMR experiments including 1H, 13C, gCOSY, gHSQC, gHMBC, and NOESY.     

Complete assignments of 1H and 13C NMR data for three new arylnaphthalene lignan from Justicia procumbens

Three new arylnaphthalene lignans, named neojusticin C (1), procumbenoside C (2) and procumbenoside D (3), have been isolated from the whole plant of Justicia procumbens, together with three known ones, justicidinoside B (4), justicidinoside C (5), and diphyllin-1-O-beta-D-apiofuranoside (6). The complete assignments of 1H and 13C NMR data for three new lignans were first obtained by means of 2D NMR techniques, including HSQC and HMBC.     

Complete assignment of 1H and 13C NMR data of some flavonol derivatives

Nine flavonol derivatives were studied. Previously reported NMR data of three of these derivatives were corrected. We report complete assignments of the NMR data for six flavonol derivatives not previously studied.     

Complete assignments of the 1H and 13C NMR spectra of 9,10-didehydro retinoic acids

A new class of retinoic acids was synthesized containing a 9,10-rigid bond. 1H and 13C NMR spectra were assigned for eight new compounds (all-E, 13Z) containing a carboxylic acid or tertiobutylester polar end group. Assignments were based on the combination of one- and two-dimensional experiments (APT, COSY, HMBC).     

1H and 13C chemical shifts for some 6,6a-dihydrochromeno(3,4-b)chromene derivatives

The 1H and 13C NMR resonances of five 6,6a-dihydrochromeno(3,4-b)chromene derivatives were assigned completely with certainty using a concerted application of one- and two-dimensional experiments (DEPT, gs-COSY, gs-HMQC and gs-HMBC).     

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.     

Complete assignments of 1H and 13C NMR data for 21 naphthalenyl‐phenyl‐pyrazoline derivatives

To find potent new chemotherapy drugs, we designed and synthesized a series of naphthochalcones bearing naphthalenyl‐phenyl‐pyrazoline moieties. The complete ¹H and ¹³C NMR data for these compounds are reported here and can be used to identify further new naphthochalcones bearing the desired pyrazoline moieties. Copyright © 2013 John Wiley & Sons, Ltd.