A diastereoselective strategy for dihydrophenanthrene-fused spirooxindoles via [1,2]-phospha-Brook rearrangement.

A highly diastereoselective, one-pot strategy for spirooxindoles bearing dihydrophenanthrenes from readily available isatins and p -quinone methides ( p -QMs) has been disclosed. Here, a sequential umpolung process via [1,2]-phospha-Brook rearrangement followed by Lewis acid-mediated intramolecular cyclization was employed to furnish the desired spiro product. This protocol provides access to potential medicinally relevant varieties of spirooxindolyl dihydrophenanthrenes in good to excellent yields and diastereoselectivity (>20 : 1).