Conformational behaviour and molecular similarity of some beta 1-adrenergic ligands.

The conformational behaviour of a series of aryloxypropanolamines was investigated by means of a new procedure which allows the sampling of the molecular torsional surface in a very efficient way. The combination of such a procedure with the standard molecular mechanics algorithms for the geometry optimization gives, as a result, the definition of a powerful computational scheme for the detailed analysis of the potential energy surface of complex molecules. The compounds studied show a remarkable tendency to form intra-molecular hydrogen bonds, which seem to play a key role in determining the lowest energy structures. The indices of molecular similarity proposed by Carbó, computed for the most stable conformers, do not account for differences between diastereoisomers, and, as a consequence, can hardly be used to attempt a structure-activity correlation.