Three-component cyclization as an approach to a combinatorial library of 2H-spiro-[chromeno[2,3-c]pyrrole-1,3'-indoline]-2',3,9-triones

A versatile and efficient three-component cyclization of methyl 4-(o-hydroxyphenyl)-2,4-dioxobutanoates 1, N-substituted isatins 2, and primary amines 3 was explored to synthesize of 2H-spiro[chromeno[2,3-c]pyrrole-1,3'-indoline]-2',3,9-triones. We obtained a library of 122 derivatives with an indolin-2-one motif as an important structural fragment in natural alkaloids. This method is practical and useful strategy for constructing dihydrochromeno[2,3-c]pyrrole-3,9-diones. Most of the obtained products also have functional groups for easy and further diversification by classical reactions.