
TY  - JOUR
A1  - Rae, ID 
A1  - Rae, ID 
A1  - Simmonds, PM 
A1  - Simmonds, PM 
T1  - The Structure of Papaverine in Solution as Determined by <sup>1</sup>H Nuclear Magnetic Relaxation Methods
JF  - Australian Journal of Chemistry
JO  - Aust. J. Chem.
Y1  - 1987
VL  - 40
IS  - 5
SP  - 915
EP  - 923
KW  - 
UR  - https://doi.org/10.1071/CH9870915 
N2  - Hydrogen relaxation in the papaverine molecule in CDCl3 solution has been studied so as to derive the conformation about the C1-CH2 bond. This was done for papaverine itself, in which the resonances of H5 and H8 were reassigned on the basis of NOESY spectra, and in the 7-OC2H3 analogue, the spectrum of which confirms the reassignment. The value for the torsional angle C 8a-C1-CH2-C lays between 70 and 92º, in good agreement with those found in crystals of papaverine , its hydrochloride, and the related alkaloid isosevanine (all in the range 68-94º). Conformational energy calculations show a broad energy minimum over the range 60-70º. The 6,7-methylenedioxy analogue of papaverine has essentially the same conformation but tumbles more rapidly in solution, the Tc value for it being 1.9&#215;10-1ls whereas values for papaverine were 5.6&#215;10-11 s (from 1H relaxation) and 3.1&#215;1011 s (from 13C relaxation). 
ER  -

