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 OPEN ACCESSMolecules 2015, 20 8224 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.

Molecular structure investigation towards pharmacodynamic activity and QSAR analysis on hypoxanthine using experimental and computational tools

“…Thus, the resonance effect was found by forming hydroxyl group. In this venture, the double bond was found to be more polarized and the corresponding p-bond length was reduced much when compared with the literature [17].…”

Computational studies of 2-(4-oxo-3-phenylthiazolidin-2-ylidene)malononitrile

“…Generally the nitrile stretching vibration is present at 2250 ± 10 cm −1 in saturated nitriles or in olefinic nitriles where no conjugation exists between the nitrile and the olefinic group [68, 69]. While in conjugated nitrile, the band moves to lower frequency of 2225 ± 7 cm −1 [69, 70]. Here in this molecule, there are two nitrile groups attached to the C=C so the symmetric and asymmetric υ C≡N modes are predicted at 2251 and 2241 cm −1 [71].…”

New Diethyl Ammonium Salt of Thiobarbituric Acid Derivative: Synthesis, Molecular Structure Investigations and Docking Studies

“…The synthetic pathway for the preparation of 3 is depicted in Scheme 1. Compound 1 , N , N -diethylthiobarbituric acid, is commercially available, while ( E )-(1 E ,4 E )-1,5- bis (4-fluorophenyl)penta-1,4-dien-3-one 2 was prepared according to the method described by Islam et al [23]. The reaction of equimolar ratios of 1 with dienone 2 in DCM in the presence of NHEt 2 as a base gave the desired compound in good overall yield in only 30 min at room temperature.…”