Multicomponent Cascade Reactions and Skeletal Rearrangements of Isatins for the Synthesis of Functionalized Pyrrolo[1,2- <i>c</i> ]quinazolin-5(6 <i>H</i> )-ones

This study developed a novel and efficient method for the synthesis of structurally diverse pyrrolo[1,2-<i>c</i>]quinazolin-5(6<i>H</i>)-ones (<b>4</b>). The method involved an unprecedented multicomponent cascade reaction of isatins (<b>1</b>), chromone-3-carboxaldehydes (<b>2</b>), and ammonium acetate (<b>3)</b> in N,<i>N</i>-dimethylformamide, with pivalic acid serving as the promoter. Under simple reflux conditions, this one-pot transformation readily affords highly functionalized derivatives <b>4</b> through the formation of four new bonds (three C-N and one C═C) as well as the cleavage of two bonds (one C-C and one C-O). The method exhibited broad substrate scope and versatility, enabling access to a wide range of pyrrolo[1,2-<i>c</i>]quinazolin-5(6<i>H</i>)-ones suitable for combinatorial and parallel synthesis of natural product-like pyrroloquinazolinone derivatives. Key advantages of this method include the use of readily available starting materials, atom-efficient transformation, efficient skeletal rearrangement, and the potential for generating bioactive molecular frameworks.