THE CRYSTALLINE CONFORMATION AND PACKING OF FLUORO-MUSCARINE AND ALLO-FLUORO-MUSCARINE IODIDES - THE EFFECT OF HYDROXYL GROUP SUBSTITUTION BY FLUORINE

The crystalline conformations of fluoro-muscarine and allo-fluoro-musc arine iodides were determined by X-ray diffraction to investigate the effect of hydroxyl substitution by a fluorine atom. Comparison with mu scarine analogues suggests that the T-4(3) ring conformation adopted b y fluoro-muscarine should be close to the minimum energy ring conforma tion of muscarine. allo-Fluoro-muscarine shows a different conformatio n, consistent with its different substitution pattern. Calculations on model compounds confirm the similarities of the conformational behavi or of muscarine and its fluorinated analogue. The fluorine role is evi dent in the packing of the title compounds which are quasi-isomorphic even if the molecular conformations are different.