The configurational assignment of 2 and E nitrogen derivatives (>C=N--The configurations of dienic nitriles have been previously assigned from through-space effects affecting proton chemical shifts'. The application of cyclic compounds 1 and 2, obtained from isophorone ( 3 5 5 -trimethyl-2-cyclohexen-l-one), has been demonstrated for this approach. The effect of the electric field is the determining factor in assigning configurational isomers, in both dienic nitriles and ketones. ',2 Our purpose is to extend this methodology to the evaluation of through-space effects on the two isomers of the nitrogen derivatives of ketones corresponding to the general formula ZC=N-Y.The Z and E diastereoisomers in the following series of six isophorone derivatives were therefore synthesized and separated: oxime, 0-methyloxime, dimethylhydrazone, tertbutylimine, N,N,N-trimethylhydrazonium iodide and oxime hydrochloride.
RESULTS AND DISCUSSION
Configurational assignmentThe value of models 1 and 2 is due mainly to the simplicity of their 'H NMR spectra. The assignment of the H-2, H-3 and H-5 proton signals is straightforward. Only H-4 exhibits a long-range coupling with the ethylenic proton, so that its signal is broader than that of H-6, as already demonstrated for dienic nitriles and ketones.' The NMR chemical shifts obtained for derivatives 1 and 2 are shown in
The reduction of several cyclohexenone oximes using lithium aluminum hydride and sodium dihydrobis-(2-methoxyethoxy)aluminate yields saturated and unsaturated aziridines with a 7-azabicyclo[4.1.0]heptane skeleton and cyclohex-2-ene amines. The use of oximes of E and/or Z configuration demonstrates the regioselectivity of the reduction and allows us to propose reaction schemes explaining the formation of the different types of products.
Electron impact ionization-collision-induced dissociation (EI-CID) and negative ion chemical ionization-collisioninduced dissociation (NICI-CID) experiments have been performed on the molecular or quasi-molecular ions(M+' or [M -m-) of series of terpenoid alcohols, using a Fourier transform ion cyclotron resonance spectrometer. These terpenes belong to the p-menthane family and bear a hydroxyl group in various positions relative to the isopropyl or isopropenyl substituent (positional or stereochemical isomers). In the case of positional isomers, different CID spectra were always obtained. Within a given diastereoisomeric series, stereochemical differences were also observed in both NICI-CID and EI-CID experiments.
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