Asymmetric Mannich Reaction of Aryl Methyl Ketones with Cyclic Imines Benzo[e][1,2,3]oxathiazine 2,2-Dioxides Catalyzed by Cinchona Alkaloid-based Primary Amines

作者：Cui, Xiao-Yu; Duan, Hui-Xin; Zhang, Yongna^*; Wang, You-Qing^*

来源：Chemistry-An Asian Journal, 2016, 11(21): 3118-3125.

DOI：10.1002/asia.201601149

• asymmetric catalysis
• ketones
• Mannich reaction
• nitrogen heterocycles
• organocatalysis

Aryl ketones represent problematic substrates for asymmetric Mannich reactions due to a large steric hindrance exhibited by such compound species. A highly enantioselective direct Mannich reaction of aryl methyl ketones with cyclic imine benzo[e][1,2,3]oxathiazine 2,2-dioxides could be successfully carried out utilizing a combination of cinchona alkaloid-derived primary amines with trifluoroacetic acid (TFA); the primary amines feature a superior catalytic efficacy over secondary amines with a variety of sterically hindered carbonyl compounds as substrates. The reaction proceeded well with various cyclic imines in 89-97% ee and with various aryl methyl ketones in 85-98% ee. Moreover, the aryl carbonyl of a Mannich product could be transformed to ketoxime, which further undergoes a Beckmann rearrangement to produce an amide compound while maintaining enantioselectivity.

• 出版日期2016-11
• 单位河南大学