Oxonium/Sulfonium Ylide Rearrangements to Access Chromenes and Thiochromenes: Concerted or Stepwise Pathway?

Area of Science:

• Organic Chemistry
• Catalysis
• Medicinal Chemistry

Background:

• Diazo arylidene succinimides (DAS) are versatile precursors in organic synthesis.
• Intramolecular rearrangements offer efficient pathways to complex heterocyclic frameworks.
• Metal-catalyzed transformations are crucial for developing novel synthetic methodologies.

Purpose of the Study:

• To develop a dirhodium(II)-catalyzed regio-divergent intramolecular rearrangement of DAS derivatives.
• To synthesize bioactive chromene and thiochromene scaffolds.
• To explore the reactivity of allyloxy- and thioallyl-substituted DAS under metal catalysis.

Main Methods:

• Synthesis of allyloxy- and thioallyl-substituted DAS derivatives.
• Dirhodium(II) catalysis for intramolecular rearrangement reactions.
• Room temperature reaction conditions and mild workup procedures.

Main Results:

• Achieved regio-divergent intramolecular rearrangement of oxonium and sulfonium ylides generated from DAS.
• Successfully synthesized chromene frameworks via [1,2]- and [1,4]-shifts.
• Extended the strategy to synthesize thiochromenes from thioallyl-substituted DAS derivatives.

Conclusions:

• This study presents the first exploration of intramolecular rearrangement on DAS derivatives for synthesizing bioactive scaffolds.
• The developed method provides a mild and efficient route to chromenes and thiochromenes.
• The dirhodium(II)-catalyzed reaction offers a valuable tool for accessing medicinally relevant heterocyclic compounds.