1 3 J IRAN CHEM SOC (2016) 13:645–651 DOI 10.1007/s13738-015-0776-8 ORIGINAL PAPER Catalyst-free and selective oxidation of pyridine derivatives and tertiary amines to corresponding N-oxides with 1,2-diphenyl-1,1,2,2-tetrahydroperoxyethane Davood Azarifar 1 · Boshra Mahmoudi 1 Received: 9 June 2015 / Accepted: 2 November 2015 / Published online: 18 November 2015 © Iranian Chemical Society 2015 Keywords Oxidation · Pyridine-N-oxide · 1,2-Diphenyl- 1,1,2,2-tetrahydroperoxyethane · Catalyst-free Introduction Heterocyclic N-oxides such as pyridine-N-oxide (PNO) and its derivatives represent an important class of compounds with ever-increasing importance owing to their useful- ness as synthetic intermediates and biological value [1, 2]. Also, these compounds have been used as oxidants, auxil- iary agents, protecting groups, and ligands in metal com- plexes and catalysts [3–7], and as useful reagents in radi- cal decarboxylations [1, 2]. In addition, a wide variety of pyridine-N-oxides have been explored which exhibit anti- HIV activity [8–10]. A number of pyridine-N-oxides such as pyridine-N-oxide congener JPL-133 have been known as active inhibitors towards HIV-1 strains targeting HIV-1 Abstract The catalyst-free oxidation of various pyri- dine derivatives and tertiary amines to their corresponding N-oxides with 1,1,2,2-tetrahydroperoxy-1,2-diphenyle- thane as an efficient oxidant has been developed. The meth- odology proved to tolerate a number of functional groups. The reactions proceeded smoothly under solvent-free and mild conditions at room temperature. All the products were easily extracted from the reaction mixtures in excellent yields. Graphical abstract The catalyst-free oxidation of vari- ous pyridine derivatives and tertiary amines to their corre- sponding N-oxides with 1,1,2,2-tetrahydroperoxy-1,2-di- phenylethane as an efficient oxidant has been developed. The methodology proved to tolerate a number of functional groups. The reactions proceeded smoothly under solvent- free and mild conditions at room temperature. All the prod- ucts were easily extracted from the reaction mixtures in excellent yields. * Davood Azarifar dazarifar@gmail.com; azarifar@basu.ac.ir 1 Faculty of Chemistry, Bu-Ali Sina University, Hamedan 65178, Iran reverse transcriptase (RT) and/or HIV-2 strains [8–11]. Also, other closely related pyridine-N-oxide derivatives are known which act against human cytomegalovirus. The methods described in the literature for preparation of pyridine-N-oxides are usually accomplished employing peracids [12], such as peracetic acid, m-chloroperbenzoic acid (MCPBA) [13–16], magnesium monoperphthalate