Spectral and Theoretical studies of some N-nitroso-t(3)-isopropyl-r(2),c(6)-bis(p-halophenyl)piperidin-4-ones

Author Details
S. Sivakumar^1,*, 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

Abstract
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