Author/Authors :
HabibiKhorassani, S. M. university of sistan and baluchestan - Department of Chemistry, زاهدان, ايران , Ansari Fard, M. university of sistan and baluchestan - Department of Chemistry, زاهدان, ايران , Mohammadi, M. university of sistan and baluchestan - Department of Chemistry, زاهدان, ايران , Aghdaei, E. university of sistan and baluchestan - Department of Chemistry, زاهدان, ايران , Shahraki, M. university of sistan and baluchestan - Department of Chemistry, زاهدان, ايران , Hadizadeh, M. university of sistan and baluchestan - Department of Chemistry, زاهدان, ايران , Hazeri, N. university of sistan and baluchestan - Department of Chemistry, زاهدان, ايران
Abstract :
Stable phosphorus ylide was obtained from a simple and efficient one-pot threecomponentreaction between triethyl phosphite and dimethyl acetylenedicarboxylate (DMAD) inthe presence of 4,5-dihydrothiazole-2-thiol in a dry diethyl ether at ambient temperature in highyield. The ^1H NMR spectrum of this compound exhibited dynamic effect that is attributed torestricted rotation around the carbon-carbon double bond. The experimental rotational energybarrier (ΔG^≠) on the basis of ^1H NMR study for the rotational interchangeable process of the two Z- and E-isomeres in ylide 4 equal to (63 ± 2) kJ.mol^-1. In addition, theoretical study was investigated on the basis of rotation around the carbon-carbon double bond using ab initiomethod at HF/6-31G level of theory. The theoretical rotational energy barrier (82 ± 2) kJ.mol^-1 for this interconversion was in agreement with the experimental data.
Keywords :
Dynamic ^1H NMR , Restricted rotation , HF , 6 , 31G level theory , Triethyl phosphate.
