Synthesis of 2-(1-(4-((2-hydroxyarylidene)amino)phenyl)ethylidene) anils

Organic photo- and thermochromic compounds have received particular attention of chemists, due to their potential applications as materials for optical data processing,electronic display systems, optical switching devices, ophthalmic glasses, molecular motors, the second order nonlinear optical (NLO) materials, and biomedical applications [1]. N-Salicylideneanilines (anils, SAs) are among the most attractive photo- and thermochromic compounds because they are used as sensors, optical data storage, and display devices [2]. Also, SAs and their derivatives exhibit solvatochromic and liquid-crystalline properties. In 1909, Senier and Shepheard discovered that SAs exhibited photochromism both in solution and in the solid state [3]. After this discovery, and especially from 1939 onwards, these compounds, which are sensitive to light and heat, have been considered for several reasons, including they are relatively straightforward to synthesize, easy to handle and use in the solid state, resistant to fatigue, and their ability to switch between three different forms (enol, cis-keto, and trans-keto forms). The photochromic and thermocromic process in SAs consists of a reversible tautomerization between enol-form and cis-keto form followed by cis-keto to trans-keto pedal motion [4]. In this work, the synthesis was successfully achieved via two steps according to Scheme 1. In the first step, 1-(4-((2- hydroxyarylidene)amino)phenyl)ethan-1-ones (3) were obtained by condensation of aminoacetophenones (1) with salicylaldehydes (2) in ethanol at room temperature (rt). Then, anils (3) were treated with active nitrile compounds (4) in the presence of ammonium acetate to aff ord 2-(1-(4-((2-hydroxyarylidene)amino)phenyl)ethylidene) derivatives (anil-nitriles) (5) in good yields