Methyloxirane and monordene

Again following the principle that the same coupling constant holds for the coupling partner, the H shift values of the protons on the positions C-1 to C-9 of monordene can be assigned (A, Sh), as can the multiplicities and the coupling constants (B, Hz). 

The relative configurations of vicinal protons follow from the characteristic values of their coupling constants. Thus 16.1 Hz confirms the trans relationship of the protons on C-8 and C-9, 10.8 Hz confirms the cis relationship of the protons on C-6 and C-1. The 2.0 Hz coupling is common to the oxirane protons at = 3.00 and i.27 this value fixes the trans relationship of the protons at C-4 and C-5 following a comparison with the corresponding coupling in the methyloxirane (2.6 Hz). The anti relationship of the protons A-H and h-H can be recognised from their 8.7 Hz coup- 

The absolute eonfiguration, (25, 45, 55 as shown or 2R,4R,5R), eannot be dedueed by NMR. For larger structures the insertion of the shift values and the coupling constants in the stereo projection of the struetural formula, from whieh one ean eonstruet a Dreiding model, proves useful in providing an overview of the stereoehemieal relationships. 

12 2-Methyl-6-(W,/V-dimethylamino)-frans-4-nitro-frans-5-phenyl-cyclohexene 

An examination of the eross signals of the HH COSY diagram leads to the proton eonneetivities shown in A starting from the alkene proton at 5// =5.67. 

12 2-Methyl-6-(f/,N-dimethylamino)-(rans-4-nitro-frafis-5-phenyl-cyclohexene 

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