Proton magnetic resonance spectra. See

Although the linear structure of the anhydrodeoxyhexitols (21) and (22) obtained firom the 0x0 reaction of 3,4-di-O-acetyl-D-arabinal (see Section III,3, p. 69) was readily deduced by an analysis of their proton magnetic resonance spectra, their stereochemistry at C-5 could not be ascertained, because of overlapping peaks. 

A brief introduction to the temperature-dependence of proton magnetic resonance spectra was given in Section 1.6 (see p. 63). 

Nuclear magnetic resonance spectra Proton magnetic resonance spectroscopy. See Nuclear magnetic resonance spectroscopy... 

Treatment of (7r-RCHCH==CH2)Fe(CO)3 (R = H, Me, MeCO) with nitric oxide yields the isoelectronic nitrosyls (w-RCHCH=CH2)Fe(NO)-(CO)2 (5, 72) (see Table II). The proton magnetic resonance spectra of these suggest structure (X) for these compounds. 

Fig. 5. Proton magnetic resonance spectra (100 MHz) for batrachotoxin class alkaloids and assignments. Chemical shifts in ppm (5) for deuterochloroform with a tetramethylsilane standard. Assignments A pyrrole NH B pyrrole 5-H C olefinic proton at C-7 D oleflnic proton at C-16 proton at C-20 FI4-OCH2 and proton at C-11 G one proton at C-15, the other appears at 6 2.3 methylene protons at C-18 / pyrrole 2-CH3 T and / pyrrole 2-CH2CH3 / NCH3 K pyrrole 4-CH3 L 2I-CH3 M I9-CH3 (see Fig. 4)...

For proton magnetic resonance and infrared spectra, see Birch and co-workers. ... 

Fig. 3.—Fourier-transform, Proton Magnetic Resonance Spectra45 of 6-Deoxy-l,2 3,4-di-O-isopropylidene-6-phthalimido-a-D-gaIactopyranose (54) (0.06 mg) at 90 MHz, Obtained by Transformation (N = 4,096) of the Free-induction Decay Signal (1,024 Datum Points, see Fig. 2), After the Appendation of 3,072 Zero, Datum Points ( Zerofilling, See Text), [(a) Spectrum associated with the real part of the transform, and (b) with the imaginary part (c) absorption-mode spectrum computed by phase correction of the spectrum in (a) and (d) dispersion-mode spectrum computed by phase correction of the spectrum in (b). Parameters for phase correction, A —255° and B —215°. Note that the phase of the tetramethylsilane and chloroform signals in (c) is slightly different from that of the carbohydrate derivative. By coincidence, the peak for residual water in spectrum (c) has almost the same intensity as the methyl signals, and could have been mistaken for one, had other spectra not been recorded.]...

VI. For details of the mass spectra, see Refs. 3, 73, 96, and 127. For proton and carbon-13 magnetic resonance spectra data, see Refs. 76 and 96 and references to synthetic material cited in Ref. 5. For FTIR spectra, see Ref. 

The proton magnetic resonance assignments for 241D have been presented (87). The optical rotation, is -1-39° (0.2, CHjOH). The structure of 241D has been confirmed by synthesis (M. W. Edwards, personal communication, 1990). None of the other amphibian piperidines has been isolated for further spectral analysis. However, Bohlmann bands in FTIR spectra will allow assignment of cis or trans configurations to such 2,6-disubstituted piperidines (see Section III,B). 

The nuclear magnetic resonance spectra show no aldehydic protons, so that the aldehyde groups are fully hydrated or exist as hemiacetals. As shown, the ds isomer consists of two, anomeric, cyclic hemiacetals. The trans isomer, however, cannot form a cyclic hemiacetal in aqueous solution, it is hydrated (34, R = H) in alcoholic solvents (R OH), it forms a hemiacetal (34) and, in the anhydrous, solid form, it is probably a polymeric hemiacetal. The large changes in R/ values in changing from alcoholic to non-alcoholic solvents (see Section VI, p. 199) provide evidence for the easy formation of hemiacetals with alcohols. 

The nuclear magnetic resonance spectra of osazones and then-acetates (see Figs. 1 and 2) afford additional proof of the acyclic structure of the osazones. Both the acyclic osazone acetates and the free osazone, such as (43), show two imino protons in their nuclear magnetic resonance spectra which disappear on deuteration, and, as cyclization as in (48) would result in the formation of a third imino proton, it may be concluded that the free osazone exists mainly in the acyclic form (43). 

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