Sacrificial azomethine ylide cycloaddition controlled chemoselective nitrile oxide cycloaddition to 1-methyl-3,5-bis[(E)-arylmethylidene]tetrahydro-4(1H)-pyridinones: formation of mono-spiro-isoxazolines

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• 作者：Raju Ranjith Kumar ; Subbu Perumal
• 关键词：Piperidone ; 1 ; 3-Dipolar cycloaddition ; Azomethine ylide ; Nitrile oxide ; Isoxazolines ; Dioxazoles
• 刊名：Tetrahedron
• 出版年：2007
• 期刊代码：107_00404020
• 类别：ch
• 出版时间：3 December 2007
• 卷：63
• 期：49
• 页码：12220-12231
• 文件大小：836 K

摘要

The 1,3-dipolar cycloaddition of an azomethine ylide to 1-methyl-3,5-bis[(E)-arylmethylidene]tetrahydro-4(1H)-pyridinones afforded novel spiro-pyrrolidines in good yields. Further cycloaddition of these spiro-pyrrolidines with nitrile oxide afforded mono-spiro-isoxazolines in moderate yields (45–56%), presumably via a di-spiro intermediate, which undergoes a spontaneous cycloreversion of the spiro-pyrrolidine unit. In contrast, the direct cycloaddition of nitrile oxide to 1-methyl-3,5-bis[(E)-arylmethylidene]tetrahydro-4(1H)-pyridinones gave the mono-spiro-isoxazoline as the minor product, while the bis-spiro-isoxazolines are formed predominantly.