Two-Step Sequence Multicomponent Synthesis/Reductive Rearrangement of 2-Acyl-2,3-dihydrofurans for Modular Assembly of Annulated 4H-Pyrans

A variety of trans-2-acyl-2,3-dihydrofurans have been assembled from readily available structurally diverse precursors and then rearranged into a series of annulated 4H-pyrans by the action of Sm/TMSCl or Zn/ZrCl4 redox systems. Present synthetic sequence is claimed as a modular approach to hetero- and carbon-fused 4H-pyrans. The rearrangement involves the SET reduction of carbonyl group to carbene followed by rare type of [1,2]-aroxyl shift. Synthetic toolbar was enriched with the use of the Zn/ZrCl4 redox system.

Automated summary

A variety of trans-2-acyl-2,3-dihydrofurans have been assembled and rearranged into annulated 4H-pyrans using Sm/TMSCl or Zn/ZrCl4 redox systems. The rearrangement involves SET reduction of carbonyl group to carbene followed by rare [1,2]-aroxyl shift. The use of Zn/ZrCl4 redox system enriched the synthetic toolbar.