Substituent-Controlled Selective Synthesis of Spirooxindoles and Oxazolyloxindoles via Two Tandem Reactions

A common synthetic method involving two tandem processes to prepare varieties of oxindole derivatives, which are important bioactive cores that exist widely in natural products and drugs, from similar materials under mild conditions is described. Herein a substituent-controlled product-selective strategy succeeded in synthesizing spirooxindoles and oxazolyloxindoles with excellent diastereoselectivity from methyleneindolinones and -bromoamides. The synthesis has clear chemoselectivity, which relies on different substituent groups at the nitrogen atoms of -bromoamides. From mechanism analysis, the spirooxindoles were constructed via elimination-Michael-Michael addition from N-benzyloxy--bromoamides, while oxazolyloxindoles were achieved via cyclization-Michael addition from N-benzoyl--bromoamides, both of which cleverly combined the nucleophilic component formation and nucleophile-triggered cascade reactions in one pot.