Nitrilimine cycloaddition onto 2-azetidinones bearing alkenyl dipolarophile(s)

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• 作者：Del Buttero ; Paola ; Molteni ; Giorgio ; Pilati ; Tullio
• 关键词：Nitrilimine cycloaddition ; Alkenyl-2-azetidinones ; Stereoselective synthesis ; 4 ; 5-Dihydropyrazoles
• 刊名：Tetrahedron
• 出版年：2005
• 期刊代码：107_00404020
• 类别：ch
• 出版时间：February 28, 2005
• 卷：61
• 期：9
• 页码：2413-2419
• 文件大小：399 K

摘要

Silver acetate-promoted nitrilimines cycloaddition onto 3(R*)-phenyl-4(R*)-cinnamoyl-2-azetidinone 1 were highly stereoselective giving 4-(4,5-dihydropyrazol-5-yl) carbonyl-2-azetidinones 5 as the major products and regioisomeric 4-(4,5-dihydropyrazol-4-yl) carbonyl-2-azetidinones 6 as the minor one. When the same protocol was applied to the novel 3(R*)-phenyl-4(S*)-(4-benzoyl-E,E-1,3-butadienyl)-2-azetidinone 2 it resulted in site- and regioselective but not stereoselective cycloaddition, involving the formation of the four cycloadducts 10–13.