S. Sivakumar1,*, A. Manimekalai2, R. Arulraj3, Hemaramesh4 and S. Savithri 5
1, 4, 5 Department of Chemistry, Sri Manakula vinayagar Engineering College, Madagadipet, Pondicherry-605107,
2Department of Chemistry, Annamalai University, Annamalainagar-608 002, India
3Department of Chemistry, Bharathiar University, Coimbatore-641046, India
N-nitroso-t(3)-isopropyl-r(2),c(6)-bis(p-halorophenyl)piperidin-4-ones 1–2 and their parent piperidin-4-ones 3-4 were synthesized and Characterized by IR, Mass , 1H and 13C NMR spectral studies. The spectra reveal the presence of two rotameric forms (syn and anti) in solution for 1–2. 1H-1H and 1H-13C COSY spectra have been recorded to assist the assignment of the signals for the syn and anti isomers of 1–2. Coupling constants predict an equilibrium mixture of boat conformation B1/B5 and alternate chair form CA for 1–2. The molecular structures of 1–2 were also determined using DFT calculations available in Dmol3 package and the results have been compared with the results derived from spectral studies and single crystal measurements. The effect of varying the substituents at nitrogen on the 1H and 13C chemical shifts has been analyzed in detail.
Keywords: N-nitrosopiperidin-4-ones, Spectral, Theoretical, Conformation, Dmol3 package