Synthesis and NMR characteristics of N‐acetyl‐4‐nitro,N‐acetyl‐5‐nitro,N‐acetyl‐6‐nitro and N‐acetyl‐7‐nitrotryptophan methyl esters

N‐acetyl‐4‐nitrotryptophan methyl ester (2), N‐acetyl‐5‐nitrotryptophan methyl ester (3), N‐acetyl‐6‐nitrotryptophan methyl ester (4) and N‐acetyl‐7‐nitrotryptophan methyl ester (5) were synthesized through a modified malonic ester reaction of the appropriate nitrogramine analogs followed by methylation with BF₃‐methanol. Assignments of the ¹H and ¹³C NMR chemical shifts were made using a combination of ¹H–¹H COSY, ¹H–¹³C HETCOR and ¹H–¹³C selective INEPT experiments. Copyright © 2008 Crown in the right of Canada. Published by John Wiley & Sons, Ltd     

One‐step synthesis of 6‐acetamido‐3‐(N‐(2‐(dimethylamino) ethyl) sulfamoyl) naphthalene‐1‐yl 7‐acetamido‐4‐hydroxynaphthalene‐2‐sulfonate and its characterization with 1D and 2D NMR techniques

A one‐step method was reported for the synthesis of 6‐acetamido‐3‐(N‐(2‐(dimethylamino) ethyl) sulfamoyl) naphthalene‐1‐yl 7‐acetamido‐4‐hydroxynaphthalene‐2‐sulfonate by treating 7‐acetamido‐4‐hydroxy‐2‐naphthalenesulfonyl chloride with equal moles of N, N‐dimethylethylenediamine in acetonitrile in the presence of K₂CO₃. The chemical structure of the obtained compounds was characterized by MS, FTIR, ¹H NMR, ¹³C NMR, gCOSY, TOCSY, gHSQC, and gHMBC. The chemical shift differences of ¹H and ¹³C being δ 0.04 and 0.2, respectively, were unambiguously differentiated. Copyright © 2013 John Wiley & Sons, Ltd.     

1H, 13C NMR studies of new 3‐aminophenol isomers linked to pyridinium salts

¹H and ¹³C NMR spectroscopic data of 20 new non‐symmetrical compounds were assigned by a combination of 1D and 2D NMR experiments (DEPT, HSQC, and HMBC). These compounds contain a 4‐(N,N‐dimethylamino)‐ or 4‐(pyrrolidin‐1‐yl)pyridinium moiety and a 3‐nitro‐, 3‐amino‐, or 3‐hydroxyphenyl ring, linked by p‐xylene, 4,4′‐dimethylbiphenyl, 1,2‐bis(p‐tolyl)ethane, or 1,4‐bis(p‐tolyl)butane. Copyright © 2013 John Wiley & Sons, Ltd.     

Complete assignment of 1H and 13C NMR spectra of α‐phenylsulfinyl‐N‐methoxy‐ N‐methylpropionamide and some p‐substituted derivatives

The complete assignment of the ¹H and ¹³C NMR spectra of the diastereomeric pairs of some α‐arylsulfinyl‐substituted N‐methoxy‐N‐methylpropionamides with the substituents methoxy, methyl, chloro, nitro is reported. Copyright © 2008 John Wiley & Sons, Ltd.     

1H and 13C NMR analysis of 2‐acetamido‐3‐mercapto‐3‐methyl‐N‐aryl‐butanamides and 2‐acetamido‐3‐methyl‐3‐nitrososulfanyl‐N‐aryl‐butanamide derivatives

The complete assignment of the ¹H and ¹³C NMR spectra of various 2‐acetamido‐3‐mercapto‐3‐methyl‐N‐aryl‐butanamides and 2‐acetamide‐3‐methyl‐3‐nitrososulfanyl‐N‐aryl‐butanamides with p‐methoxy, o‐chloro and m‐chloro substituents is reported. Copyright © 2013 John Wiley & Sons, Ltd.     

Hydroacridines: Part 23. 1H and 13C NMR spectra of sym‐octahydroacridine,its 9‐(3‐pyridyl) and 9‐(4‐pyridyl) derivatives and the corresponding N(10)‐oxides. An experimental approach to the diamagnetic anisotropy of the pyridine nucleus

The complete ¹H NMR chemical shift assignments of 1,2,3,4,5,6,7,8‐octahydroacridine ( 1 ), 1,2,3,4,5,6,7,8‐octahydro‐9‐(3‐pyridyl)acridine ( 2 ), 1,2,3,4,5,6,7,8‐octahydro‐9‐(4‐pyridyl)acridine ( 3 ) and the corresponding N(10)‐oxides 1a , 2a and 3a , respectively, were achieved on the basis of 400 MHz ¹H NMR spectra and proton–proton decoupling, HMQC and NOEDIFF experiments. The spectral data for the above compounds provided the first experimental evidence of the difference in the anisotropy effect of the two non‐symmetrical moieties of the pyridine nucleus, and allowed us to ascertain that the shielding effect of the moiety defined by the C(2′)—N—C(6′) atoms is weaker than that of the C(3′)—C(4′)—C(5′) moiety. The ¹³C NMR spectra of 1 – 3 and 1a – 3a and the effect of N(10)‐oxidation on the ¹³C NMR chemical shifts are also discussed. The N‐oxidation of 2 and 3 with m‐chloroperbenzoic acid occurred regiospecifically, affording the N(10)‐oxides 2a and 3a free of N(1′)‐oxide isomers. Copyright © 2002 John Wiley & Sons, Ltd.     

1H and 13C NMR spectral assignment of N,N′‐disubstituted thiourea and urea derivatives active against nitric oxide synthase

The ¹H and ¹³C NMR resonances of seventeen N‐alkyl and aryl‐N′‐[3‐hydroxy‐3‐(2‐nitro‐5‐substitutedphenyl)propyl]‐thioureas and ureas ( 1–17 ), and seventeen N‐alkyl or aryl‐N′‐[3‐(2‐amino‐5‐substitutedphenyl)‐3‐hydroxypropyl]‐thioureas and ureas ( 18–34 ), designed as NOS inhibitors, were assigned completely using the concerted application of one‐ and two‐dimensional experiments (DEPT, HSQC and HMBC). NOESY studies confirm the preferred conformation of these compounds. Copyright © 2016 John Wiley & Sons, Ltd.     

1H and 13C chemical shifts for acridines: Part XVIII. 9‐Chloroacridine and 9‐(N‐allyl)‐ and 9‐(N‐propargyl)acridinamine derivatives

The¹H and ¹³C NMR resonances for acridine derivatives 9‐substituted with chloro, allylamino and propargylamino groups were completely assigned using a concerted application of gs‐COSY, gs‐HMQC and gs‐HMBC experiments. 9‐(N‐Allyl)‐ and 9‐(N‐propargyl)acridinamine derivatives present amino–imino tautomerism including a large broadening of ¹H and ¹³C NMR signals at room temperature. To obtain suitable resolution, therefore, these latter compounds were studied at 370 K in DMSO‐d6 solutions and showed a complete shift towards the imino tautomers. Copyright © 2003 John Wiley & Sons, Ltd.     

N‐N migration of a carbamoyl group in a pyrazole derivative revealed by NMR

During a synthesis of 5‐amino‐4‐(6‐methoxy‐2‐methylpyridin‐3‐yl)‐3‐methyl‐1H‐pyrazole‐1‐carboxamide (see Scheme 1), a side‐reaction produced 3‐amino‐4‐(6‐methoxy‐2‐methylpyridin‐3‐yl)‐5‐methyl‐1H‐pyrazole‐1‐carboxamide as a by‐product that forms an equilibrium with the target‐compound. The structure of the by‐product was elucidated by the interpretation of 1D and 2D (HMQC, HMBC) NMR data where ¹H‐¹⁵ N HMBC correlations revealed the position of carbamoyl group attachment on the pyrazole. Comparison of structures of the target‐compound and the by‐product showed that the latter resulted from N‐N migration of the carbamoyl group in the target‐compound. Copyright © 2013 John Wiley & Sons, Ltd.     

NMR studies on 1,2‐dihydro‐2‐(4‐aminophenyl)‐4‐[4‐(4‐aminophenoxy)‐4‐phenyl]‐(2H)phthalazin‐1‐one

An unsymmetrical heterocyclic diamine, 1,2‐dihydro‐2‐(4‐aminophenyl)‐4‐[4‐(4‐aminophenoxy)‐4‐phenyl]‐(2H)phthalazin‐1‐one, was synthesized. Its ¹H and ¹³C NMR spectra were completely assigned by utilizing the two‐dimensional heteronuclear ¹³C–¹H multiple‐bond coherence (HMBC) spectroscopy, and heteronuclear ¹³C–¹H one‐bond correlation spectroscopy, homonuclear shift correlation spectroscopy (H,H‐COSY) and rotating frame Overhauser enhancement spectroscopy (ROESY). The structure of the compound was shown to be the phthalazinone rather than the phthalazine ether from cross peaks and chemical shifts of the protons. Copyright © 2002 John Wiley & Sons, Ltd.     

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.     

NMR study of E/Z isomerism in N‐alkoxybenzoimidic acid derivatives

Well defined E/Z isomers of N‐methoxy‐p‐nitrobenzimidoyl chloride, N‐methoxybenzimidoyl chloride, methyl N‐methylbenzohydroximate and ethyl N‐hydroxybenzimidate were prepared in order to provide model data for studies of benzhydroximic acid derivatives and related compounds. NMR parameters [¹H, ¹³C and ¹⁵N chemical shifts and ¹J(¹³C, ¹³C) coupling constants] were determined. The results show that stereochemically most significant are the values of ¹J(¹³C, ¹³C) couplings between aromatic C_ipso and C?N carbons and that the relationship, |J_cis| > |J_trans|, known for this coupling from oximes, is not affected by electronegative substituents at the C?N carbon atom, but the values are. Copyright © 2002 John Wiley & Sons, Ltd.     

13C GIAO DFT calculation as a tool for configuration prediction of N–O group in saturated heterocyclic N‐oxides

Tropane, tropinone, pseudopelletierine and cocaine were oxidized in situ in a nuclear magnetic resonance (NMR) tube providing mixtures of exo/endo N‐oxides. Observed ¹³C chemical shifts were correlated with values calculated by gauge‐including atomic orbitals density functional theory (DFT) OPBE/6‐31G* method using DFT B3LYP/6‐31G* optimized geometries. The same method of ¹³C chemical shift calculation was applied on series of methyl‐substituted 1‐methylpiperidines and their epimeric N‐oxides described in literature. The results show that using this undemanding calculation method enables assignment of configuration of N–O group in N‐epimeric saturated heterocyclic N‐oxides. The approach enables assigning of the configuration with high degree of certainty even if NMR data of only one isomer are available. An improved method of in situ oxidation of starting amines in an NMR tube is also described. Copyright © 2012 John Wiley & Sons, Ltd.     

NMR analysis of mono‐ and difructosyllactosucrose synthesized by 1F‐fructosyltransferase purified from roots of asparagus (Asparagus officinalis L.)

Two novel oligosaccharides, mono‐ and difructosyllactosucrose {[O‐β‐D ‐fructofuranosyl‐(2 → 1)]_n‐β‐D ‐fructofuranosyl‐O‐[β‐D ‐galactopyranosyl‐(1 → 4)]‐α‐D ‐glucopyranoside, n = 1 and 2} were synthesized using 1^F‐fructosyltransferase purified form roots of asparagus (Asparagus officinalis L.). Their ¹H and ¹³C NMR spectra were assigned using several NMR techniques. The spectral analysis was started from two anomeric methines of aldose units, galactose and glucose, since they showed separate characteristic signals in their ¹H and ¹³C NMR spectra. After assignments of all the ¹H and ¹³C signals of two units of aldose, they were discriminated as galactose and glucose using proton–proton coupling constants. The HMBC spectrum revealed the galactose residue attached to C‐4 of glucose, fructose residue attached to the C‐1 of glucose, and further fructosyl fructose linkage extended from the glucosyl fructose residues. Copyright © 2002 John Wiley & Sons, Ltd.     

Hydroacridines: Part 30. 1H and 13C NMR spectra of 9‐substituted 1,2,3,4,5,6,7,8‐octahydroacridines and of their N‐oxides

The ¹H and ¹³C NMR chemical shifts of 1,2,3,4,5,6,7,8‐octahydroacridine, 12 of its 9‐substituted derivatives, and of the corresponding N‐oxides were determined, assigned, and discussed in terms of 9‐substituent effects and effects of N‐oxidation. A good linear correlation was found between the ¹³C chemical shifts of the aromatic carbons in octahydroacridines and those of respective carbons in the corresponding N‐oxides. Copyright © 2009 John Wiley & Sons, Ltd.     

Complete assignment of the 1H and 13C NMR spectra of four 2‐substituted 4a,8a‐cis‐endo‐5,8‐methano‐4a,5,8,8a‐tetrahydronaphthalene‐1,4‐diones

The complete assignment of the ¹H and ¹³C NMR spectra of the title enediones, bearing as substituents N‐aziridinyl (a novel compound), methoxy, chloro and methylsulfanyl, is reported. Copyright © 2002 John Wiley & Sons, Ltd.     

Z and E rotamers of N‐formyl‐1‐bromo‐4‐hydroxy‐3‐methoxymorphinan‐6‐one and their interconversion as studied by 1H/13C NMR spectroscopy and quantum chemical calculations

N‐Formyl‐1‐bromo‐4‐hydroxy‐3‐methoxymorphinan‐6‐one (compound 2 ), an important intermediate in the NIH Opiate Total Synthesis, presumably exists as a mixture of two rotamers (Z and E) in both CHCl₃ and DMSO at room temperature due to the hindered rotation of its N‐C18 bond in the amide moiety. By comparing the experimental ¹H and ¹³C chemical shifts of a single rotamer and the mixture of compound 2 in CDCl₃ with the calculated chemical shifts of the geometry optimized Z and E rotamers utilizing density functional theory, the crystalline rotamer of compound 2 was characterized as having the E configuration. The energy barrier between the two rotamers was also determined with the temperature dependence of ¹H and ¹³C NMR coalescence experiments, and then compared with that from the reaction path for the interconversion of the two rotamers calculated at the level of B3LYP/6‐31G*. Detailed geometry of the ground state and the transition states of both rotamers are given and discussed. Copyright © 2012 This article is a US Government work and is in the public domain in the USA.     

Complete assignment of the 1H and 13C NMR spectra of some N‐benzyl‐(piperidin or pyrrolidin)‐purines

The ¹H and ¹³C shifts of six N‐benzyl‐(piperidin or pyrrolidin)‐purines were fully assigned by a combination of HSQC and HMBC experiments. The ¹H,¹H coupling constants were also determined. Copyright © 2002 John Wiley & Sons, Ltd.     

Solution 1H and 13C NMR of new chiral 1,4‐oxazepinium heterocycles and their intermediates from the reaction of 2,4‐pentanedione with α‐L‐amino acids and (R)‐(—)‐2‐phenylglycinol

The reaction of 2,4‐pentanedione ( 1 ) with (R)‐(—)‐2‐phenylglycine methyl ester ( 2 ), (R)‐(—)‐2‐phenylglycinol ( 3 ) and the proteinogenic amino acids (2S,3R)‐(—)‐2‐amino‐3‐hydroxybutyric acid (L ‐threonine) ( 4 ) and (R)‐(—)‐2‐amino‐3‐mercaptopropionic acid (L ‐cysteine) ( 5 ) methyl esters was investigated. The corresponding enamines 6 , 7 and 8 were isolated and characterized spectroscopically whereas 9 , which is unstable, was transformed in situ into 13 . Treatment of 7 , 8 and 9 with boron trifluoride etherate afforded the new [1,4]oxazepines 10 , 11 and [1,4]thiazepine ( 12 ) as their BF₃O^? salts. The structures of the enamines and their corresponding seven‐membered heterocycles were assessed by 1D and 2D NMR spectroscopy. Variable‐temperature experiments revealed different molecular mobility behavior among these heterocycles. Copyright © 2003 John Wiley & Sons, Ltd.     

Synthesis and 1H and 13C NMR structural analysis of cis‐ and trans‐2‐imino‐1,3‐ and ‐3,1‐perhydrobenzoxazines and their 3‐ and 1‐N‐methyl derivatives

cis‐ and trans‐2‐imino‐1,3‐ and ‐3,1‐perhydrobenzoxazines and the N‐methyl derivatives of the latter were synthesized from the corresponding cyclic 1,3‐amino alcohol with cyanogen bromide. The configurations of the studied compounds were confirmed by ¹H and ¹³C NMR spectra. All trans‐fused compounds exist in biased chair–chair conformations as expected, whereas the cis‐fused 1,3‐benzoxazines attain exclusively the O‐in conformations. The cis‐fused 3,1‐benzoxazines, especially the 1‐methyl‐substituted derivatives, tend to favor the N‐out form, obviously owing to the favorable axial orientation of this N‐methyl. Copyright © 2003 John Wiley & Sons, Ltd.