Synthesis and complete NMR spectral assignment of thiophene-substituted sulfinyl monomers

This paper describes the synthesis of thiophene-substituted sulfinyl monomers. It comprises a four-step reaction by which the thiophene unit is built in via Suzuki coupling. These monomers could be used as building blocks for the preparation of conducting polymers via a new concept: the sulfinyl precursor route i.e. via thiophene substituted poly(p-phenylenevinylene) precursors. Furthermore, the complete 1H and 13C NMR signal assignment is presented. In addition to being essential for the characterization of the polymers concerned, it offers useful input information for further improvement of chemical shift prediction software. Furthermore, the T1C relaxation decay times are demonstrated to have the potential of being a fast and robust criterion for the spectral assignment of analogous monomers.     

Structure elucidation and complete NMR spectral assignment of an unusual aromatic monacolin analog from Monascus purpureus-fermented rice

One unusual aromatic monacolin analog, monacophenyl, was isolated from the ethanolic extract of Monascus purpureus-fermented rice. Its structure was completely and unambiguously assigned by one- and two-dimensional NMR techniques ((1)H NMR, (13)C NMR, HSQC, HMBC and NOESY) and high-resolution ESI-MS spectrometry.     

Structure elucidation and NMR spectral assignment of five new xanthones from the bark of Garcinia xanthochymus

Five new xanthones, namely Garcinexanthones A-E (1-5), were isolated from the barks of Garcinia xanthochymus. Their structures were elucidated by spectral analysis, primarily NMR, MS, and UV. The complete assignments of the (1)H NMR and (13)C NMR chemical shifts for the compounds were achieved by using 1D and 2D NMR techniques, including DEPT, HSQC, and HMBC NMR experiments.     

13C NMR spectral assignment of five epimeric 3alpha- versus 3beta-functionalized cholestane pairs

(13)C NMR chemical shift assignments of five alpha- and beta- epimeric pairs of cholestanes functionalized at C-3 are presented. Empirical increment estimations proved to be a valuable tool for the unequivocal structural elucidation when compared with the chemical shift values of cholestanes derivatized by introduction of N- and S-containing groups at C-3 in equatorial and axial positions. Moreover, the possibility is demonstrated to anticipate the effect of -OC(S)R substituents at neighboring carbon atoms of the ring A backbone.     

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.     

Structural elucidation and NMR spectral assignment of three new furostanol saponins from the roots of Tupistra chinensis

Three new furostanol saponins (1–3) were isolated from the roots of Tupistra chinensis (T. chinensis). And their structures were elucidated on the basis of NMR and mass spectrometry (MS) spectral analysis. Copyright © 2009 John Wiley & Sons, Ltd.     

Structure elucidation and complete NMR spectral assignments of glucosylated saponins of cantalasaponin I

Five new glucosylated steroidal glycosides, cantalasaponin I‐B₁ (1), I‐B₂ (2), I‐B₃ (3), I‐B₄ (4) and I‐B₅ (5), were isolated and purified from the transformed product of the cantalasaponin I by using Toruzyme 3.0 l as biocatalyst. Their structures were elucidated on the basis of high‐resolution electrospray ionization mass spectrometry, one‐dimensional (¹H and ¹³C NMR) and two‐dimensional [COSY, heteronuclear single‐quantum correlation (HSQC), HMBC and HSQC‐TOCSY] NMR spectral analyses and chemical evidence. Copyright © 2012 John Wiley & Sons, Ltd.     

Structure elucidation and complete NMR spectral assignments of new furostanol glycosides from Solanum torvum

Two new furostanol glycosides, torvosides O (1) and P (2), were isolated from leaves of Solanum torvum. Their structures were completely and unambiguously assigned by one‐ and two‐dimensional NMR techniques (¹H NMR, ¹³C NMR, TOCSY, HSQC, ROESY and HMBC), ESI‐MS spectrometry and chemical methods. Copyright © 2009 John Wiley & Sons, Ltd.     

Structure elucidation and complete NMR spectral assignments of two new dammarane-type tetraglycosides from Panax quinquefolium

Two new saponins were isolated from leaves of Panax quinquefolium and their structures were elucidated as 3beta, 12beta, 20S-trihydroxy-25-methoxydammar-23-ene 3-O-{[beta-D-glucopyranosyl(1-->2)-beta-D-glucopyranosyl]-20-O-[alpha-L-arabinopyranosyl(1-->6)]-beta-D-glucopyranoside (1) and 3beta, 20S-dihydroxy-12beta, 23R-epoxydammar-24-ene 3-O-{[beta-D-glucopyranosyl(1-->2)-beta-D-glucopyranosyl]-20-O-[beta-D-xylopyanosyl(1-->6)]-beta-D-glucopyranoside (2) on the basis of (1)D and (2)D NMR (including (1)H, (13)C-NMR, (1)H-(1)H COSY, HSQC, TOCSY, HMBC, and NOESY), ESI-MS spectrometry and chemical methods.     

Complete assignment of (1)H and (13)C NMR data of dihydroxyflavone derivatives

Six flavone derivatives were studied. Previously reported NMR data of three of these derivatives were corrected and the NMR data for the other three derivatives not studied previously were completely assigned on the basis of the basic 1D and 2D NMR experiments and molecular modeling.     

Complete 1H and 13C NMR assignment for aryl diisoprenes

The characterization of four aryl diisoprenes was carried out by 1D‐ and 2D‐NMR methods, which permitted the assignment of the signals of all protons and all carbon atoms. Copyright © 2003 John Wiley & Sons, Ltd.     

1H and 13C spectral assignment of 2(1H)-pyridone derivatives

1H and 13C NMR spectroscopic data for 4-aryl-3,4-dihydro-6-methyl-2(1H)pyridone derivatives were fully assigned by a combination of one- and two- dimensional experiments (DEPT, HMBC, HMQC, COSY, NOE).     

1H and 13C NMR signal assignment of synthetic (-)-methyl thyrsiflorin B acetate, (-)-thyrsiflorin C and several scopadulane derivatives

The (1)H and (13)C NMR signal assignment of the data of 13 scopadulane-type diterpenes is reported. It was based on one- and two- dimensional NMR techniques which included (1)H, (13)C, DEPT, HMQC and 1D NOE difference spectroscopy.     

Structural and spectral assignment of a new diterpenoid isolated from Ballota undulata and a complete (1)H and (13)C NMR data assignment for three other structurally related compounds

The structure of 3beta-hydroxyballotinone, a new labdane diterpenoid isolated from Ballota undulata, has been established by NMR spectroscopic studies. In addition, complete and unambiguous assignments of the (1)H and (13)C NMR spectra of three other already known labdanes (ballotinone, ballonigrin and ballonigrinone) isolated from the same source have been achieved. The assignments are based on 2D shift-correlated (1)H--(1)H COSY, (1)H--(13)C gHSQC [(1)J(C,H)] and (1)H--(13)C gHMBC [(n)J(C,H) (n = 2 and 3)], and NOE experiments.     

Synthesis and complete assignment of the 1H and 13C NMR signals of some oxopyrancoumarin and oxofuropyrancoumarin derivatives

The synthesis of four pyranocoumarins starting from phloroglucinol and the complete (1)H and (13)C NMR assignment of seven pyranocoumarins has been performed using 1D and 2D NMR techniques including COSY, HMQC and HMBC experiments.     

Structure elucidation of the dye Acid Red 131: complete 1H, 13C and 15N NMR data assignment

The chemistry of dyes and pigments is relevant to the textile industry, because of the importance to establish the best conditions for the finishing process and to understand the interactions among various compounds to yield the correct hue and nuances. For this reason, the molecular structure of a monoazo acid dye, C.I. Acid Red 131, was elucidated and characterized by homo‐ and hetero‐nuclear NMR, MS, IR and UV spectroscopy techniques. Copyright © 2011 John Wiley & Sons, Ltd.     

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 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.     

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.     

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.