A two-stage approach to automatic determination of 1H NMR coupling constants.

(1)H NMR scalar coupling constants are a rich source of information on molecular structure, but their extraction from spectra can be less than straightforward. Previous approaches to J extraction include methods proposed by Hoye, Golotvin, and the 'modified J-doubling' method. Here we describe the ACCA method, currently implemented in the NMR package MestReC, which allows a high degree of automation in the extraction of coupling patterns even in the case of complex multiplets with sublinewidth splitting. The new approach is illustrated by application to strychnine, for which it has detected previously unreported couplings.

13C and 1H NMR of 2,6-diaryl-1-hydroxy piperidin-4-one oximes; substituent effects on cis/trans ratio and conformational equilibria.

The reaction of substituted diarylidene acetones with hydroxylamine hydrochloride affords isomeric N-hydroxy diaryl piperidinone oximes as main products. The structures as well as conformational equilibria of these products were established by 1H and 13C NMR spectroscopy and further studied by variable temperature NMR. It was found that the cis/trans ratio of 2,6-substituted piperidine derivatives depended on the position of the substituent on the aromatic ring.