Cascade Annulation for Synthesizing Chromenopyrrolones from -Hydroxyphenyl Enaminones and 2-Halo--alkyloxyacetamides.

A cascade cyclization reaction comprising two halogenation reactions and a Michael addition was developed for the synthesis of chromeno[2,3-]pyrrole-3-ones . Additionally, another cascade cyclization reaction, which involves a halogenation reaction followed by two intramolecular Michael additions, was established for the synthesis of chromeno[2,3-]pyrrole-2-ones . Both types of compounds were synthesized from -hydroxyphenyl enaminones and 2-halo--alkyloxyacetamides through a process that facilitated the intramolecular formation of C-C, C-O, and C-N bonds to effectively establish two fused rings in a single operation. This novel protocol is efficient, uses readily accessible starting materials, and operates under mild conditions, demonstrating tolerance for various functional groups while achieving good yields.