Synthesis, characterization and computational studies for (2′S,3R,3′S,8a′R)‐2′,3′‐bis(ethoxycarbonyl)‐2‐oxo‐2′,3′‐dihydro‐8a′H‐spiro[indoline‐3,1′‐indolizine]‐6′‐carboxylic acid and some derivatives

In this article, we present advances related to 1,3‐dipolar cycloadditions of generated pyridinium ylides and apply these results to specific 1,3‐dipolar cycloaddition reactions with oxindole dipolarophiles. The ylide discussed in this article is generated from alkylation reactions between substituted pyridines and a primary electrophile. Cycloaddition reactions proceeding from pyridinium ylides and various oxindoles are reported with good stereo‐ and regioselectivity. Cycloaddition reactions take place by the overlap of the HOMO of the dipole and the LUMO of the dipolarophile when the two orbitals have similar energies, resulting in the formation of two new bonds. To get more insight into the reaction nature, a quantum chemical simulation was performed. A computational study is performed on the reactants (pyridinium ylides and oxindoles) and resulting cycloadducts. The present analysis reveals that the cycloaddition reactions under study can be classified in the normal electron demand category. Regioselectivity and mechanism of 1,3‐cycloaddition reactions are studied in the light of several theoretical approaches such as activation energy, Houk's rule based on the FMO theory, and the DFT reactivity indices. 1,3‐dipolar cycloadditions of generated pyridinium ylides were applied to specific 1,3‐dipolar cycloaddition reactions with oxindole dipolarophiles. Computational study is performed on the reactants (pyridinium ylides and oxindoles) and resulting cycloadducts. The present analysis reveals that the cylcloaddition reactions under study can be classified in the normal electron demond category. Regioselectivity and mechanism of 1,3‐cycloaddition reactions are studied in the light of several theoretical approaches such as activation energy, Houk's rule based on the FMO theory, and the DTF reactivity indices.