Investigation on the weak interactions assembling the crystal structures of Betti bases

The crystal structures of (S, S)-aminobenzylnaphthols, easily produced by a chromatography-free highly stereoselective Betti reaction, were investigated by means of single crystal X-ray diffraction analysis, and the main intra-and intermolecular interactions were described. The presence of a strong intramolecular hydrogen bond was confirmed, whereas the whole crystal building was found to be due mainly to other bondings, such as CH center dot center dot center dot O and CH center dot center dot center dot pi interactions. As far as the last interactions were concerned, we observed many short distances from one hydrogen atom to an aryl plane, together with the appropriate geometric requirements for the assemblies. The observations suggest that these interactions can play a relevant role in the crystal building. The absence of similar short distance CH center dot center dot center dot pi interactions in the crystal of a diastereomeric (R, S)-aminobenzylnaphthol could be a suggestion of the preferential crystallisation of the (S, S)-stereoisomer and, consequently, its prevalence as a product of the Betti reaction.