Solvent influence in the Rh-catalyzed intramolecular 1,6 C-H insertions: a general approach to the chromane and flavanone skeletons

Solvent polarity and nature of the ligands on the catalyst are crucial factors that control the regioselectivity of the Rh(II) promoted intramolecular 1,6 C-H insertions versus the β-elimination. We have explored the best conditions for the preparation of flavanones and chromenes through this approach. The procedure is also an excellent way of preparing stereochemically pure Z aryl-alkenes.