Conformational study of n,n'-(alkane-1,n-diyl)bis(2-phenyl-3,5-dihydro-4H-imidazol-4-one)s with different spacer length

Introduction

n,n'-(Alkanediyl)-bis(2-phenyl-3,5-dihydro-4H-imidazol-4-one)s (1) are of interest not only from the point of view of their chemical structure, but due to the properties of their N-alkylated derivatives. The latter are a class of biogenic QACs, which have antiseptic and disinfectant properties that have become especially relevant over the past few years. In this study, we investigated the conformational abilities of the titled compounds to gain insight into their biological potential as a platform for the generation of various QACs.

Experimental

The ¹H and ¹³C NMR spectra were recorded with a Varian (Agilent) 400 spectrometer. Quantum chemical calculations were performed using DFT at the B3LYP/6-31G(d,p) theory. Conformational analysis of the synthesized compounds was carried out using the Frog2 program followed by the optimization by the MM method AMMOS.

Results and Discussion

Among the conformers of 1, due to the flexibility of the polymethylene fragment, the phenyl rings can take on different mutual arrangements, while there is a clear tendency for the formation of π-π interactions of the rings. From the point of view of reactivity towards alkylating agents, a preliminary conclusion can be drawn about the favorable mutual arrangement of imidazolone rings, located at a sufficient distance to carry out both mono- and bisalkylation to obtain bis-QAC.