title: Hydrogen-bond-assisted organocatalytic acetalization of secondary alcohols: experimental and theoretical studies.
abstract: An efficient method was developed for the acetalization of secondary alcohols in the presence of simple protic pyridinium salts. Direct correlations between the structure and activity of the synthesized catalysts were described. Stabilization via hydrogen bonding of the hemiacetal intermediate by the pyridine derivatives, along with an appropriate increase in the reaction rate, was revealed. The nature of the observed experimental acceleration of the examined reactions catalyzed by pyridinium salts comprising electron-withdrawing groups at certain positions of the pyridinium ring was studied. In this vein, the interpretation of the hydrogen-bonded pretransition-state complexes and transition-state complexes with strong catalysts was also discussed in terms of partial proton transfer. It was concluded that optimized pretransition-state complexes of the catalyst and reactant are useful for the prediction of catalyst efficiency prior to the experiment.
authors.affiliation: †Nizhny Novgorod State Technical University n.a. R.E. Alekseev, 24 minin st., Nizhny Novgorod 603950, Russia.|‡Lobachevsky State University of Nizhni Novgorod, 23 Prospekt Gagarina (Gagarin Avenue), Nizhny Novgorod 603950, Russia.
authors.forename: Misha
authors.initials: M
authors.lastname: Rumyantsev
authors.affiliation: ‡Lobachevsky State University of Nizhni Novgorod, 23 Prospekt Gagarina (Gagarin Avenue), Nizhny Novgorod 603950, Russia.
authors.forename: Nikolay S
authors.initials: NS
authors.lastname: Sitnikov
authors.affiliation: ‡Lobachevsky State University of Nizhni Novgorod, 23 Prospekt Gagarina (Gagarin Avenue), Nizhny Novgorod 603950, Russia.
authors.forename: Nikolay V
authors.initials: NV
authors.lastname: Somov