10.1021/acs.joc.0c00882
The study presents an organocatalytic cascade reaction for synthesizing spirocyclic benzothiophenones with multiple stereocenters. The key chemicals involved are 2-alkylidene benzo[b]thiophenone derivatives acting as Michael acceptors and enones as donors. The reaction is catalyzed by a primary amine derived from cinchonidine, with 4-nitrobenzoic acid used as an additive. The process efficiently produces spirobenzothiophenonic cyclohexane derivatives with high yields (88-96%), enantioselectivities (85-97% ee), and diastereoselectivities (approximately 14/2/1). The synthesized compounds, containing three stereocenters, are valuable for their potential applications in medicinal chemistry due to their interesting physiochemical properties and biological activities. The study also explores the scope and limitations of the method, demonstrating its applicability with various enones and benzothiophenone derivatives, and showcases the potential for further transformations of the spirocompounds.
10.1016/j.tetlet.2008.01.009
The research focuses on the selective oxidation of sulfides to sulfoxides using heterocyclic amine salts of Keggin heteropolyacids as catalysts. The study explores the effectiveness of various heteropolyacids, including those derived from quinoline (PM12Qui), cinchonidine (PM12Cid), and cinchonine (PM12Cin), in combination with different green oxidants such as hydrogen peroxide, urea–hydrogen peroxide complex, sodium percarbonate, and tert-butyl-hydroperoxide. The experiments were conducted under various conditions to optimize the reaction yields and selectivity. Key findings include the high catalytic activity and recoverability of the cinchonine heteropolyacid catalyst, which also demonstrated enantioselectivity in the oxidation process. The study highlights the operational simplicity, mild reaction conditions, and high yields achieved, positioning these catalysts as a green alternative for the oxidation of sulfides to sulfoxides.
Xn,
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