Utilization of Solid Acid SO₄²⁻/TiO₂ as Catalyst to the Three‐Component Mannich Reaction at Ambient Temperature

Abstract

in Wiley Online Library (wileyonlinelibrary.com). The three-component Mannich reaction of among dimethyl malonate, aromatic primary amine, and aromatic aldehyde was made successfully in the presence of solid acidic catalyst SO 4 2À /TiO 2 , with excellent catalytic activity, as compared to SO 4 2À /γ-Al 2 O 3 and SO 4 2À /ZnO. To the best of our knowledge, SO 4 2À / TiO 2 prepared at varied calcination temperatures can perform different intensities of Lewis and Brønsted acidities. Because of this point, under the optimum conditions, the effect of SO 4 2À /TiO 2 (prepared at 200°C) was much more than that of SO 4 2À /TiO 2 (prepared at 300°C or 400°C) in the three-component Mannich reaction. In observing ionization activation mode of the three-component Mannich reaction, it disclosed that the plausible mechanism possibly undergoes formation of aldimines and transformation of aldimines into β-amino esters by applying solid acidic catalyst SO 4 2À /M x O y . Dimethyl-2-((4-methylbenzo[d]thiazol-2-ylamino)(2-fluorophenyl)methyl)malonate (8). As a colorless oil, yield: 25%;1 H-NMR (500 MHz, CDCl 3 , 25°C, TMS): δ (ppm) 7.46 (t, J = 7.4 Hz, 1H), 7.39 (d, J = 8.0 Hz, 1H), 7.23-7.31 (m, 1H), 7.05 (q, J = 7.4 Hz, 3H), 6.99 (t, J = 8.0 Hz, 1H), 2526

Advances in Mannich‐type Reactions Based on the Classification of Compounds with Activated α‐H

“…In base catalysis, a weak base such as triethylamine bearing a pair of lone electrons captured the active proton from the α‐carbon of dimethyl malonate to be a strong nucleophile, thus attacking the unactivated substituent to obtain the β‐amino ester (Scheme 18b). Comparing the two activation modes, the yield of acid catalysis was higher than that of base catalysis under the same conditions, indicating that the activation energy of the whole reaction catalyzed by acid was lower than that catalyzed by the base [23] …”

“…Comparing the two activation modes, the yield of acid catalysis was higher than that of base catalysis under the same conditions, indicating that the activation energy of the whole reaction catalyzed by acid was lower than that catalyzed by the base. [23] In 2020, Smita R. Waghmare introduced a novel and efficient NH 4 Cl-catalyzed one-pot reaction of aromatic amines, aromatic aldehydes or their respective imines with malonate esters, synthesizing β-amino esters in excellent yield (60 %-98 %) (Scheme 19). The authors examined the reactions of various imines 98 with malonate esters 99 using ethanol as solvent at room temperature.…”

Sulfated Titania (TiO2‐SO42−) as an Efficient Catalyst for Organic Synthesis: Overarching Review from 2000 to 2021

“…Shu et al [82] has reported the three-component Mannich reaction of aromatic aldehyde, aromatic primary amine and dimethyl malonate in presence of TiO Scheme 25. Esterification of phthalic anhydride.…”

“…TiO 2 -SO 4 2À catalyzed three-component Mannich reaction (prepared at 200 °C). [82] Scheme 29. Mechanism that explains the β-amino esters formation.…”

Synthesis of a New Series of N‐Mannich Bases and Polyhydroxy Mannich Bases of Pharmaceutical Interest Related to Isatin and Its Schiff Bases

“…The N‐ Mannich bases derived from NH ‐heterocycles and their derivatives have received significant attention due to their wide range of biological and pharmacological activities . In particular, much interest has centered around N‐ Mannich bases of isatin, and related compounds, which possess a broad spectrum of action including antibacterial , anticonvulsant , anti‐HIV , antifungal , cytotoxic, and anticancer activities.…”