An Occurrence of Attractive Alkyl-Phenyl Interaction. The Conformations of Several 1-Phenyl-2-alkanols

The conformations have been studied, by means of NMR spectroscopy, for a series of 1-alkyl-substituted 2-phenylethyl alcohols with the structure C6H5CH2CH(OH)–R, where R=CH3 (1), C2H5 (2), i-C3H7 (3), and t-C4H9 (4). It has been suggested that a rotamer in which the phenyl group is oriented gauche to the alkyl (R) and anti to the hydroxyl group is most populated in the conformational equilibria of 1–3. Another rotamer (in which Ph is anti to R) has, on the other hand, been suggested to be preferred in the conformational equilibrium of 4. The results have been discussed in the light of the presence of an attractive alkyl-phenyl interaction (CH–π interaction).