Intramolecular [4 + 2] Trapping of a Hexadehydro-Diels–Alder (HDDA) Benzyne by Tethered Arenes

We
report here the efficient, intramolecular trapping in a Diels–Alder
(DA) sense of thermally generated benzynes by one of two pendant arene
rings. A more electron-rich ring (p-methoxyphenyl)
reacted substantially faster than a simple phenyl ring, which was,
in turn, slightly more reactive vs a 4-carbo­methoxy­phenyl
ring. Photoinduced di-π-methane rearrangement of the initial
DA adducts gave rise to unusual isomeric polycyclic adducts.