1H and 13C NMR spectral assignments of novel chromenylchalcones

Several types of chalcones containing 2H‐chromen group were synthesized. Claisen–Schmidt condensation of 2H‐chromen‐3‐carbaldehydes (I) with methoxy substituted acetophenones afforded (E)‐3‐(2H‐chromen‐3‐yl)‐1‐(methoxyphenyl)prop‐2‐en‐1‐ones (chromenylchalcones, 1–7). Other types of chromenylchalcone, (E)‐1‐(6‐methoxy‐2H‐chromen‐3‐yl)‐3‐(methoxyphenyl)prop‐2‐en‐1‐ones (8–13) were also obtained between reaction of methoxy substituted benzaldehydes and 1‐(6‐methoxy‐2H‐chromen‐3‐yl)ethanone (II). Dichromenylchalcones (14–16) were also synthesized through the same reaction between aldehydes (I) and ketone (II). Their complete ¹H‐NMR and ¹³C‐NMR assignments are reported here and more polysubstituted chromenylchalcones synthesized or isolated from the natural sources in the future can be identified on the basis of the NMR data reported here. Copyright © 2012 John Wiley & Sons, Ltd.     

1H and 13C NMR spectral assignments of 2′‐hydroxychalcones

Chalcones are of interest to medicinal chemists because their structures can be easily modified with various functional groups. The syntheses and biological activities of chalcones from natural sources are well known. In this study, 24 2′‐hydroxychalcones bearing methoxy substituents were synthesized, among which five are new. The NMR data for all synthesized chalcones are described for the first time. The complete assignments of the ¹H and ¹³C NMR data can be used for the identification of newly discovered and widely isolated, synthesized chalcones. Copyright © 2013 John Wiley & Sons, Ltd.     

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.     

1H and 13C NMR spectral assignments of isoquinuclidine-3,5-dione derivatives

The 1H and 13C NMR spectra of six 5-substituted 2-azabicyclo[2.2.2]octane derivatives were fully assigned by COSY and HSQC experiments.     

Detailed assignments of 1H and 13C NMR spectral data of 14 cyclopentane derivatives

Detailed assignments of ¹H and ¹³C NMR spectral data for 14 cyclopentane derivatives are reported. The assignments are based on 1D ¹H and ¹³C NMR and on 2D shift‐correlated [¹H, ¹³C‐HMQC], J‐resolved and NOEDIF experiments. Copyright © 2003 John Wiley & Sons, Ltd.     

Complete 1H and 13C NMR spectral assignments for the glycoalkaloid dehydrocommersonine

The normal levels and types of glycoalkaloids found in commercial varieties of potato (Solanum tuberosum) appear to present no hazard to human health. However when wild Solanum species are used in breeding endeavors, new and untested glycoalkaloids may be introduced. Recent studies of domestic crosses with a wild Solanum oplocense accession indicated that the levels of a non‐indigenous glycoalkaloid appeared associated with reduced defoliation by the Colorado potato beetle. The non‐indigenous glycoalkaloid was isolated from foliage of the wild S. oplocense accession and unambiguously characterized by high‐resolution electrospray ionization mass spectrometry and NM analysis as the glycoalkaloid dehydrocommersonine. Copyright © 2012 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.     

Complete assignments of (1)H and (13)C NMR spectral data of nine surfactin isomers

A new surfactin isomer (1) was isolated from a mangrove bacteria strain 'Bacillus sp'. Its structure was identified, and full assignments of (1)H and (13)C NMR spectral data were achieved for the first time by a combination of mass spectrometry and 1D and 2D NMR experiments including DEPT, (1)H-(1)H COSY, HSQC, HMBC, TOCSY, ROESY, and HSQC-TOCSY. The NMR spectral data of eight known analogs (2-9) are also reported.     

1H and 13C NMR spectral assignments of 2,4‐diaryl‐substituted cycloalkyl[d]pyrimidines

The proton and carbon spectra of new 2,4‐diaryl‐substituted cycloalkyl[d]pyrimidines prepared in a simple one‐pot reaction, are reported. Copyright © 2002 John Wiley & Sons, Ltd.     

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.     

1H and 13C NMR spectral assignments of four dammarane triterpenoids from carnauba wax

The phytochemical investigation of carnauba wax led to the isolation of three new dammarane triterpenoids 1, 2 and 4, together with the known triterpene 3. The structures of the new compounds were determined by 1D and 2D NMR spectroscopy and by comparison with published data for closely related compounds.     

Complete assignments of 1H and 13C NMR spectral data for 7,7′‐dihydroarylnaphthalene lignan lactones

In this article we present a complete ¹H and ¹³C NMR spectral analysis of three 7,7′‐dihydroarylnaphthalene lignan lactones using modern NMR techniques such as COSY, HSQC, HMBC and NOE experiments. Complete assignment and homonuclear hydrogen coupling constant measurements were performed. Copyright © 2009 John Wiley & Sons, Ltd.     

Structure elucidation and 1H/13C NMR spectral assignments of four trabectedin related compounds

This article presents the structure elucidation of four new compounds, formed during the hemisynthetic preparation of trabectedin, an anti-tumor natural product from Ecteinascidia turbinata. We report herein on the use of UV, MS and NMR spectroscopic data along with (1)H and (13)C spectral assignments obtained by means of 1D and 2D homo- and heteronuclear NMR techniques.     

Synthesis and complete assignment of NMR data of 20 chalcones

Chalcones, intermediates in flavonoid biosynthesis, can exhibit antibacterial, antiproliferative, and anti-inflammatory properties. Chalcones contain two benzene rings and both hydroxylated and methoxylated analogs are frequently produced by hydroxylases and O-methyltransferases in plant biosynthetic pathways. Assignments of NMR peaks in the spectra of hydroxylated and/or methoxylated chalcones can help in identifying novel chalcone derivatives isolated from natural sources by referencing these data against NMR spectra obtained from known chalcones. We report here the syntheses of 20 chalcones and complete assignments of (1)H and (13)C NMR spectra.