- Reaction Route and Mechanism of the Direct N-Alkylation of Sulfonamides on Acidic Mesoporous Zeolite β-Catalyst
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Development of highly active heterogeneous catalysts with strong acidity and mesoporous structure is a highly attractive strategy for organic synthesis. In this study, a mesoporous zeolite beta (HBeta-M) with bulky particle size and strong acidity was synthesized and used in the direct N-alkylation of sulfonamides with alcohols. The strongly acidic HBeta-M had a higher intrinsic activity with initial turnover frequency of 11 × 10-2 s-1 than those of H-form mordenite nanosheets (3.3 × 10-2 s-1) and montmorillonite (4.0 × 10-2 s-1) catalysts. The experiment and characterization results demonstrate that there are two parallel reaction routes on the acidic catalysts. One route is the reaction of benzhydrol with p-toluenesulfonamide (route I). Another route is the reaction of dibenzhydryl ether, arising from route I, with p-toluenesulfonamide (route II), which is found in this work. The reaction rate of route I (13 × 10-3 mol kg-1 s-1) was higher than that of route II (9.8 × 10-3 mol kg-1 s-1) on HBeta-M, but route II predominantly contributed to the formation of the target product with high selectivity. Hereby, a complete reaction mechanism is proposed in this work.
- Fu, Wenqian,Shen, Runsheng,Bai, Enhui,Zhang, Lei,Chen, Qun,Fang, Zhongxue,Li, Guangchao,Yi, Xianfeng,Zheng, Anmin,Tang, Tiandi
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- Catalyst development for organocatalytic hydrosilylation of aromatic ketones and ketimines
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A new family of Lewis basic 2-pyridyl oxazolines have been developed, which can act as efficient organocatalysts for the enantioselective reduction of prochiral aromatic ketones and ketimines with trichlorosilane, a readily available and inexpensive reagent. 1-Isoquinolyl oxazoline, derived from mandelic acid, was identified as the most efficient catalyst of the series, capable of delivering high enantioselectivities in the reduction of both ketones (up to 94% ee) and ketimines (up to 89% ee).
- Malkov, Andrei V.,Stewart-Liddon, Angus J. P.,McGeoch, Grant D.,Ramirez-Lopez, Pedro,Kocovsky, Pavel
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experimental part
p. 4864 - 4877
(2012/07/28)
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