Abstract—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.
Nitrilimine cycloaddition onto 2-azetidinones bearing alkenyl dipolarophile(s) / P. Del Buttero, G. Molteni, T. Pilati. - In: TETRAHEDRON. - ISSN 0040-4020. - 61:9(2005), pp. 2413-2419. [10.1016/j.tet.2005.01.016]
Nitrilimine cycloaddition onto 2-azetidinones bearing alkenyl dipolarophile(s)
P. Del Buttero;G. Molteni;
2005
Abstract
Abstract—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.
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