title: Synthesis, molecular structure and spectroscopic investigations of novel fluorinated spiro heterocycles.
abstract: This paper describes an efficient and regioselective method for the synthesis of novel fluorinated spiro-heterocycles in excellent yield by cascade [5+1] double Michael addition reactions. The compounds 7,11-bis(4-fluorophenyl)-2,4-dimethyl- 2,4-diazaspiro[5.5] undecane-1,3,5,9-tetraone (3a) and 2,4-dimethyl-7,11-bis (4-(trifluoromethyl)phenyl)-2,4-diazaspiro[5.5]undecane-1,3,5,9-tetraone (3b) were characterized by single-crystal X-ray diffraction, FT-IR and NMR techniques. The optimized geometrical parameters, infrared vibrational frequencies and NMR chemical shifts of the studied compounds have also been calculated using the density functional theory (DFT) method, using Becke-3-Lee-Yang-Parr functional and the 6-311G(d,p) basis set. There is good agreement between the experimentally determined structural parameters, vibrational frequencies and NMR chemical shifts of the studied compounds and those predicted theoretically. The calculated natural atomic charges using NBO method showed higher polarity of 3a compared to 3b.The calculated electronic spectra are also discussed based on the TD-DFT calculations.
authors.affiliation: Department of Chemistry, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451, Saudi Arabia. mislam@ksu.edu.sa.
authors.forename: Mohammad Shahidul
authors.initials: MS
authors.lastname: Islam
authors.affiliation: Department of Chemistry, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451, Saudi Arabia. amajid@ksu.edu.sa.
authors.forename: Abdullah Mohammed
authors.initials: AM
authors.lastname: Al-Majid
authors.affiliation: Department of Chemistry, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451, Saudi Arabia. ambarakat@ksu.edu.sa.|Department of Chemistry, Faculty of Science, Alexandria University, P.O. Box 426, Ibrahimia, Alexandria 21321, Egypt. ambarakat@ksu.edu.sa.
authors.forename: Assem
authors.initials: A
authors.lastname: Barakat
authors.affiliation: Department of Chemistry, Faculty of Science, Alexandria University, P.O. Box 426, Ibrahimia, Alexandria 21321, Egypt. saied1soliman@yahoo.com.|Department of Chemistry, Rabigh College of Science and Art, King Abdulaziz University, P.O. Box 344, Rabigh 21911, Saudi Arabia. saied1soliman@yahoo.com.
authors.forename: Saied M
authors.initials: SM
authors.lastname: Soliman
authors.affiliation: Department of Pharmaceutical Chemistry, College of Pharmacy, King Saud University, P.O. Box 2457, Riyadh 11451, Saudi Arabia. ghabbourh@yahoo.com.
authors.forename: Hazem A
authors.initials: HA
authors.lastname: Ghabbour
authors.affiliation: X-ray Crystallography Unit, School of Physics, Universiti Sains Malaysia, Penang 11800, Malaysia. ckquah@usm.my.
authors.forename: Ching Kheng
authors.initials: CK
authors.lastname: Quah
authors.affiliation: Department of Pharmaceutical Chemistry, College of Pharmacy, King Saud University, P.O. Box 2457, Riyadh 11451, Saudi Arabia. hfun.c@ksu.edu.sa.|X-ray Crystallography Unit, School of Physics, Universiti Sains Malaysia, Penang 11800, Malaysia. hfun.c@ksu.edu.sa.
authors.forename: Hoong-Kun
authors.initials: HK
authors.lastname: Fun
mesh_terms: D018360:Crystallography, X-Ray / Q000379:methods; D054879:Halogenation; D006571:Heterocyclic Compounds / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods; D013816:Thermodynamics; D014732:Vibration; D014961:X-Ray Diffraction / Q000379:methods
chemical_list: D006571:Heterocyclic Compounds