[4 + 3] Cycloadditions with Bromo-Substituted Morita–Baylis–Hillman Adducts of Isatins and N-(ortho-Chloromethyl)aryl Amides

• DOI: 10.1021/acs.orglett.5b02279
• Publication Date: 2015-09-11T20:19:04Z
• Authors: Gu Zhan; Ming-Lin Shi; Qing He; Wei Du; Ying-Chun Chen
• Keywords: Oxindole; Phosphonium; Base (topology)

Efficient construction of a challenging aza-spirocycloheptane oxindole scaffold is reported through an unprecedented [4 + 3] cycloaddition reaction with bromo-substituted Morita–Baylis–Hillman adducts isatins and N-(ortho-chloromethyl)aryl amides. Both reactive intermediates, the allylic phosphonium ylides aza-o-quinone methides, were in situ generated, chemoselectively facilitated by Lewis base Brønsted base, respectively.