Dihydrooxazine N-Oxide Intermediates as Resting States in Organocatalytic Kinetic Resolution of Functionalized Nitroallylic Amines with Aldehydes

详细信息    查看全文

• 作者：Ramani Gurubrahamam ; Yan ming Chen ; Wan-Yun Huang ; Yu-Te Chan ; Hsiang-Kai Chang ; Ming-Kang Tsai ; Kwunmin Chen
• 刊名：Organic Letters
• 出版年：2016
• 出版时间：July 1, 2016
• 年：2016
• 卷：18
• 期：13
• 页码：3046-3049
• 全文大小：355K
• 年卷期：0
• ISSN：1523-7052

文摘

Kinetic resolution of nitroallylic amines was established using chiral α,α-l-diphenylprolinol silyl ether auxiliary through isolation of the dihydrooxazine N-oxide intermediates. Further hydrolyzing the resting states provided tetrahydropyridines in high chemical yields and high to excellent stereoselectivities (up to >20:1 dr and 98% ee). A detailed mechanistic explanation for stereoselective protonation in the dihydrooxazine was probed computationally. In addition, the probable intermediates in α-halogenation of aldehydes (masked with enamines) were isolated to provide crystallographic evidence.