Efficient Synthesis of 9‑Aryldihydrophenanthrenes by a Cascade Reaction Involving Arynes and Styrenes

A mild, general, and transition-metal-free protocol for the synthesis of 9,10-dihydrophenanthrenes is reported. The aryne generated by the fluoride-induced 1,2-elimination of 2-(trimethylsilyl)­aryl triflates undergoes an efficient cascade reaction initiated by the Diels–Alder reaction with the differently substituted styrenes leading to the formation of 9-aryl-9,10-dihydrophenanthrene derivatives in moderate to good yields.