An Expedient Approach to Access Phenalenones via Unconventional [1,2]-Phospha-Brook Rearrangement/Carbonyl Migration.

An efficient protocol for the synthesis of 2,3-disubstituted phenalenones from para -quinone methides ( p -QMs) and acenaphthoquinone is described. The reaction involves P(NMe 2 ) 3 -mediated [1,2]-phospha-Brook rearrangement followed by Lewis acid-assisted 1,2-carbonyl migration to afford the 2,3-disubstituted phenalenones. The developed protocol tolerates a broad range of substrates to form a variety of phenalenones in good to excellent yields. Moreover, the utility of the synthesized phenalenones is also demonstrated by performing its transformations to other adducts.