138777-01-2Relevant academic research and scientific papers
Long-Range NMR Coupling between a Cyclopropyl Proton and a Proton next to the Ring in a Number of 2,2-Disubstituted 1,1-Dihalocyclopropanes
Sydnes, Leiv K.,Pettersen, Anita,Drabloes, Finn,Roemming, Christian
, p. 902 - 913 (2007/10/02)
Analysis of the proton NMR spectra of 2,2-dibromo-1-propylcyclopropanecarboxylic acid, 2,2-dichloro-1-propylcyclopropanecarboxylic acid and 12 1,1-dihalo-2-phenylcyclopropane derivatives with an additional substituent attached to C-2 revealed a long-range coupling (4J) between the cyclopropyl proton cis to the carboxyl or the phenyl group and one of the protons next to the three-membered ring.The absolute value of this coupling turned out to be sensitive to the properties of the substituents attached to the ring and varied from 0.56 to 1.54 Hz.By using structural data obtained by X-ray crystallography for four of the compounds and the correlations of Bystrov and Stepanyants the variation of 4J has been related to structural and conformational differences.The conformational changes are mainly due to steric interactions, which in part can be rationalized on the basis of semiempirical calculations (AM1) of the rotation of phenyl substituents in model compounds.The structures of the four cyclopropanes were determined from single-crystal diffraction data obtained at low temperature. 2-(2,2-Dibromo-1-phenylcyclopropyl)ethanoic acid: C11H10Br2O2, orthorhombic, space group Pbca, a = 8.082(1), b = 15.591(2), c = 18.264(3) Angstroem, (t = -140 deg C), Z = 8. 2-(2,2-Dichloro-1-phenylcyclopropyl)ethanoic acid: C11H10Cl2O2, orthorhombic, space group Pbca, a = 8.219(2), b = 14.956(3), c = 18.431(4) Angstroem, (t = -135 deg C), Z = 8. 2-Bromomethyl-1,1-dichloro-2-phenylcyclopropane: C10H9BrCl2, orthorhombic, space group Pbca, a = 9.263(2), b = 11.423(2), c = 20.091(3) Angstroem, (t = -135 deg C), Z = 8. 2,2-Dichloro-1-phenylcyclopropylmethyl 4-nitrobenzoate: C17H13Cl2NO4, monoclinic, space group P21/n, a = 6.210(1), b = 28.886(9), c = 9.022(3) Angstroem, (t = -135 deg C), Z = 4.The structures were refined to R values of 0.051, 0.052, 0.048 and 0.042, respectively.
