Intramolecular Hydrogen-Bonding Catalysis of Ester Aminolysis in Acetonitrile

Article abstract of DOI:10.1021/jo00155a023

o-Hydroxyphenyl benzoate (3) reacts with 1,3-diaminopropane and 1,4-diaminobutane in acetonitrile according to a two-term rate law (eq 1).The first term of this equation becomes constant when the amine concentration is greater than 0.2 M.Addition of hexamethylphosphoric triamide (HMPT) or tetra-n-butylammonium chloride inhibits this reaction path completely while leaving almost unaffected the path related to the second term of eq 1.These and other results lead to the conclusion that 3 forms a hydrogen-bonded complex with diamines through its o-OH group.HMPT and Bu4NCl can also form hydrogen-bonded complexes with 3 in competition with diamines, thus inhibiting the reaction path related to the first term of eq 1, whose mechanism is not defined by the present data.On the other hand, the second term of eq 1 relates to a mechanism of intramolecular catalysis by the o-OH group of 3 promoted by bases or in general by hydrogen-bond acceptors.These results stress the importance of hydrogen bonding in intramolecular catalysis in aprotic solvents.