NMR Study of the Aminolysis of D-Glycero-D-gulo-heptono-1,4-lactone With o-Phenylenediamine Using Four Synthetic...

1D and 2D NMR spectra of amide 3 and benzimidazole 4 were unequivocally assigned. Moreover, the aminolysis of D-glycero-D-gulo-heptono-1,4-lactone 1 with o-phenylenediamine 2 was explored using different methodologies. Results indicated that focused ultrasound selectively yielded the amide 3. Studies demonstrated that intensive cavitation can exceed the activation energy without disrupting the thermodynamic equilibrium. Thus, the kinetic product (amide 3) was favored over the thermodynamic product (benzimidazole 4). In contrast, the ultrasonic cleaner led to an incomplete and unselective reaction. On the other hand, thermal induction favored the synthesis of benzimidazole 4, while the mechanochemical synthesis was inefficient in promoting the aminolysis of the γ-lactone 1 with compound 2.