Nitrilimine cycloaddition onto 2-azetidinones bearing alkenyl dipolarophile(s)
2005; Elsevier BV; Volume: 61; Issue: 9 Linguagem: Inglês
10.1016/j.tet.2005.01.016
ISSN1464-5416
AutoresPaola Del Buttero, Giorgio Molteni, Tullio Pilati,
Tópico(s)Cyclopropane Reaction Mechanisms
ResumoSilver 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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