Experimental and theoretical study on the mechanism of stable phosphorus ylides derived from indazole in the presence of different dialkyl acetyelenedicarboxylates

In the recent work, kinetics studies were made of the reactions between triphenylphosphine 1, dialkyl acetylenedicarboxylates 2 in the presence of NH-acid, such as indazole 3. The kinetic parameters of all reactions determined by UV spectrophotometry. The second order fits were drawn and the values of the second order rate constant (k) were calculated using standard equations. Theoretical studies were performed for evaluation of potential energy surfaces of all structures participated in the reaction mechanism. The first step of all reactions was recognized as a rate determining step in the reaction mechanism, on the basis of experimental and theoretical data. Quantum mechanical calculations were clarified how the ylides exist in solution as a mixture of two geometrical isomers (Z- and E-) as a minor or major forms.

Keywords:

NH-acid , Kinetic investigation , Theoretical study , Z- and E-rotamers , Indazole , Triphenylphosphine