SYNTHESIS, SPECTRAL AND COMPUTATIONAL STUDIES OF SOME N-SUBSTITUTED t(3)-ISOPROPYL-r(2),c(6)-BIS(P-CHLOROPHENYL) PIPERIDIN-4-ONES

Many piperidine derivatives are found to possess pharmacological activity and form an essential part of the molecular structures of important drugs (Rubiralta et al., 1991; Venkatasa Perumal et al., 2001). Recently attention has been focussed on the application of the piperidone derivatives as prospective biophotonic materials (Nesterov et al., 2003; Sampathkumar et al., 2005). Since the pharmacological properties and the reactivity depend on their stereochemistry, efforts were made for the development of new synthetic techniques leading to stereo selective piperidines and their characterization (Garcia et al., 2004; Diwischek et al., 2005). Most of the piperidine precursors are known to exist in chair conformation. Electron withdrawing groups (– NO, –CHO, –COR and –CONHPh) introduced at the nitrogen atom profoundly affect the conformations of the heterocyclic ring and orientation of the substituents in 2,6-dialkyland 2,6-diaryl substituted piperidines (Manimekalai A and Sivakumar S 2010; Ravindran et al., 2002; Gdaniec et al., 1995; Pandiarajan et al., 1997; Srinivasan et al., 2004; Vijayalakshmi et al., 2006; Aridoss et al., 2007; Venkatraj et al., 2008; Thiruvalluvar et al., 2006; Jayabharathi et al., 2006; Manimekalai et al., 2007). since severe A strain exists in the normal chair conformation. In all these cases conformations which avoid A strain are favored. In an effort to create new derivatives of pharmacologically active piperidones existing in other than normal chair conformation, the present investigation was undertaken. Two N-acylr(2),c (6)bis (pchlorophenyl)-t(3)-isopropylpiperidin-4-ones 1–2 were synthesized in the present study and their conformational behavior was analyzed using H and C NMR Abstract