2H‐Phosphindole‐Enabled Dearomatization and [4+2] Cycloaddition of (Hetero)Arenes

Abstract

The heavier main group multiple bonds offer an effective tool for small molecule activation. Transient 2H‐phosphinidole working as a reactive phosphadiene system undergoes phospha‐Diels–Alder reaction with a wide range of non‐activated aromatic carbocycles and heterocycles, including naphthalene, anthracene, phenanthrene, furan, thiophene, pyrrole, pyridine, and benzo‐fused heterocycles, affording concise access to a range of polycyclic fused rings feature with phosphorus at the bridgehead. These results demonstrate that non‐activated (hetero)arenes are capable of acting as 2π systems in [4+2] cycloaddition with highly reactive 2H‐phosphindole complex.

Ring-Opening Reaction of 1-Phospha-2-Azanorbornenes via P-N Bond Cleavage and Reversibility Studies

“…Phospholes are versatile starting materials for the production of phosphorus heterocyclic compounds [1][2][3][4][5][6]. The tautomerization of poorly aromatic 1H-phospholes leads to 2H-phospholes [7], which readily undergo hetero-Diels-Alder cycloaddition reactions with various dienophiles [8][9][10][11][12][13][14].…”