Carbon-13 nuclear magnetic resonance spectrum of methaqualone

¹³C nmr chemical shifts of methaqualone, 2-methyl-3-propyl-4-quinazolone, 2-methyl-3-phenyl-4-quinazolone and their precursor, acetanthranil, are reported. The signals are assigned on the basis of suhstituent effects on benzene shifts, intensities, multiplicities in SFORD, and comparison with structurally related compounds.     

Carbon-13 nuclear magnetic resonance studies on dichloropyridoquinolines

Carbon-13 NMR chemical shifts are reported for six angular and one linear dichloropyridoquinolines in CDCl₃. The chemical shift assignments have been made using model compounds, fully coupled spectra, selective proton decoupling and results from lanthanide shift studies. Chlorine substituent effects are compared to those reported for chloroquinolines. The effect of the heteroaromatic nitrogen atoms on ¹³C? ¹H coupling constants in these polycyclic systems are compared to those reported for pyridine systems.     

The carbon-13 and nitrogen-15 nuclear magnetic resonance spectra of uroporphyrinogens I and III

Due to their sensitivity to light and air, porphyrinogens are not normally isolated, but are routinely analyzed by oxidation to the corresponding porphyrin. We report herein the ¹³C- and ¹⁵N-NMR spectra of uroporphyrinogens I and III in their “native state”, multiply labelled with ¹³C and ¹⁵N, and at natural abundance (¹³C only).     

Carbon-13 nuclear magnetic resonance spectra of veratrine components

The ¹³C NMR spectra were determined and signals assigned to the various carbons of veratridine and cevadine.     

Carbon-13 nuclear magnetic resonance spectra of substituted-s-triazolyl tetrazoles

The natural abundance carbon-13 nuclear magnetic resonance spectra of various 5-aryltetrazoles, 1-(5-aryltetrazol-2-ylacetyl)-4-phenyl thiosemicarbazides and 5-(5-aryltetrazol-2-ylmethyl)-4-phenyl-s-triazole-3-thiols were recorded using Fourier transform techniques. The chemical shifts of various carbon resonances have been assigned on the basis of chemical shift theory, the signal multiplicity observed in the single-frequency off-resonance decoupled (SFORD) spectra and comparison with the chemical shifts of the model compounds.     

Carbon-13 nuclear magnetic resonance spectra of D-homoandrostane derivatives

The ¹³C chemical shift data of a series of ketone, alcohol and ester derivatives of D-homoandrostane are reported. Homologation effects are discussed, as well as substituent effects on the homologated structures.     

Carbon-13 nuclear magnetic resonance spectroscopy of cephalotaxus alkaloids

Carbon-13 chemical shift assignments have been obtained for the naturally occurring Cephalotaxus alkaloids, cephalotaxine, acetylcephalotaxine, harringtonine, isoharringtonine, drupacine and cephalotaxinone.     

Carbon-13 nuclear magnetic resonance spectra of fentanyl analogs

Natural abundance carbon-13 chemical shifts are reported for the hydrochloride salts of fentanyl ( 1a ) and fifteen analogs. The signals are assigned on the basis of chemical shift theory, SFORD multiplicities, signal intensities, comparisons with model compounds, and thiophene carbon-proton coupling constants. In addition to its forensic value, the data suggest that the solution conformations of the analogs are similar to that of fentanyl hydrochloride.     

Carbon-13 nuclear magnetic resonance spectra of methaqualone metabolites

Carbon-13 chemical shifts are reported for methaqualone, seven hydroxylated methaqualone metabolites, and four acetate derivatives. The signals are assigned on the basis of chemical shift theory, SFORD multiplicities, signal intensities, and comparisons with model compounds.     

Carbon-13 nuclear magnetic resonance spectra of phenycyclidine analogs

Natural abundance carbon-13 chemical shifts are reported for the hydrochloride salts of phencyclidine ( 1a ) and sixteen analogs. The signals are assigned on the basis of chemical shift theory, SFORD multiplicities, signal intensities, and comparisons with model compounds. In addition to its forensic value, the data suggests that the solution conformations of the analogs are similar to that of phencyclidine hydrochloride.     

Carbon-13 nuclear magnetic resonance spectroscopy of conjugated polyynes

The ¹³C NMR spectra of several conjugated polyyne-aldehydes and ketones are compared with those of the corresponding alcohols. All data show considerable effects similar to those observed in conjugated polyenes.     

Carbon-13 nuclear magnetic resonance spectra of isoquinoline alkaloids

The ¹³C nmr ehemieal shifts of 1,2,3,4-tetrahydroisoquinoline, salsolidine and laudanosine are reported. The various carbon resonances have been assigned on the basis of chemical shift theory, intensity of the signals, multiplicities generated in SFORD spectra and the comparison with model compounds.     

Carbon-13 nuclear magnetic resonance spectra of ceveratrum alkaloids

The ¹³C NMR spectra were determined and signals assigned to the various carbons of the alkamines veracevine, germine and zygacine derived from steroidal alkaloids of the ceveratrum class. Assignment of signals was aided by analysis of the partially relaxed spectrum of cervagenine 9,12,14-orthoacetate-3, 16-diacetate.     

Carbon-13 nuclear magnetic resonance studies on high spin iron(III) porphyrins

Carbon-13 NMR studies on a series of high spin iron(III) porphyrins, namely tetraphenylporphyrin iron(III) halides [Fe(TPP) X, X=Cl, Br, I] in CDCl₃ solution are reported. As expected the¹³C shifts are found to be an order of magnitude larger than the corresponding proton shifts. The dipolar contribution, which is quite important for the proton NMR, becomes much less significant for the¹³C shifts. No systematic variation in the¹³C shift across the series is observed, except for the meso-carbon which shows a small but gradual decrease in going from the chloro to the iodo complex. The¹³C shift for the various carbon atoms of the porphyrin ligand shows interesting pattern which is discussed in terms of spin delocalisation mechanisms.     

Carbon-13 nuclear magnetic resonance spectra of some heterocyclic D-homoandrostanes

The ¹³C chemical shift data of several D-homoandrostanes with heteroatoms (N,O) in the 17a-position are reported. Heteroatom effects on the shieldings of the carbons of rings C and D are discussed.     

Carbon-13 nuclear magnetic resonance spectra of methyl 2-pyronecarboxylates

The ¹³C NMR spectra of methyl 2-pyrone-3-, 4-, 5- and 6-carboxylates were studied and the substituent effects on the 2-pyrone ring were compared with those of some model compounds. ¹H NMR spectra were also recorded and discussed. The long range ¹³C, ¹H coupling constants were obtained, discussed and proved useful in signal assignments.