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This paper reports an efficient heterogeneous catalyst based on sulfonic acid functionalization of magnetic nanoparticles. This new catalyst was prepared using the reaction between magnetic nanoparticles and sodium 2-bromoethane-1-sulfonate. Magnetic nanoparticles functionalized ethane sulfonic acid (MNESA) was found as efficient catalyst for the synthesis of coumarin derivatives using Pechmann condensation under mild condition. This reaction was catalyzed by MNESA under solvent-free condition at 90°C, to give the corresponding products in excellent yields. The catalyst is easily separated from the reaction condition and can be reused for several times with consistence in the activity.

In this study, mechanism and stereochemistry of multicomponent domino Knoevenagel/Diels–Alder reaction were investigated theoretically. Structures of reagents, transition states, intermediates, and products were optimized at M062X/6-31[Formula: see text]G(d,p) level of theory. Although the mechanism of this reaction involved several processes, including bond rotation, isomerization, asymmetric cycloaddition, acid-base, and nucleophile–electrophile competitions, critical processes were studied to provide a clearer picture of the mechanism of this valuable reaction in terms of stereochemistry considerations. According to the results, the ring closure step of reaction performed via a polar Dield-Alder mechanism, having enthalpy at approximately 40[Formula: see text]kcal/mol. The diastereoselectivity of the reaction was controlled by the interaction of dienophile with the less hindered face of diene through a more stable endo transition state ([Formula: see text] and 27.31 in methanol and gas phase, respectively). HSAB criteria could explain the regioselectivity of this reaction by considering the least softness difference ([Formula: see text]) for interacting C-atoms based on Hirshfeld populations. The result was the creation of cis-spiro cyclohexanone under kinetic and thermodynamic controls as a predominant diastereoselective and regioselective product.