Regioselectivity of Photochemical and Thermal Smiles Rearrangements and Related Reactions of β-(Nitrophenoxy)ethylamines

Article abstract of DOI:10.1021/jo00223a016

The ortho, meta, and para isomers of β-(nitrophenoxy)ethylamine (1, 2, and 3, respectively) have been synthesized as hydrochloride salts.The corresponding ortho, meta, and para isomer of β-(nitrophenoxy)ethyl alcohol (4, 5, or 6, respectively), the Smiles rearrangement product, is formed cleanly in alkaline water by a thermal reaction from 1 or 3 and by a photochemical reaction from the triplet state of 2.Photolysis of 1 or 3 does not cause Smiles rearrangement; photoproducts recovered from 1 and 3 show that β-amino group in both cases bonds at the ring carbon atom adjacent to the side chain and meta to the nitro group.The contrast of these results with those reported for photo-Smiles rearrangements of similar systems containing NHPh as the attacking nucleophile and for intermolecular aromatic photosubstitution by alkylamines is discussed.The results support the recently proposed "energy gap" model for predicting regioseelctivity in heterolytic nucleophilic aromatic photosubstitution.