Synthesis and reactivity of 2 H -pyran moiety in [60]fullerene cage skeleton

摘要

(Figure presented) The cyclopentadienyl type hexa-adduct C _(60)(OOtBu)_6 1 is readily converted into 2H-pyran containing fullerene derivative C_(60)(O)(OOH)(OOtBu)_5 2 in the presence of NaHCO_3 and hydroquinone. In the process, O-O bond of the tert-butylperoxo group on the central pentagon is cleaved, and the fullerene-bound oxygen radical inserts into a 5,6-junction to form the 2H-pyran moiety. Further reactions of 2 led to open-cage fullerenes with a nine-membered orifice and also both 3,4-dihydro-2H-pyran and 3,6-dihydro-2H-pyran containing fullerene derivatives. Mechanisms are proposed involving intramolecular S _N2′ and aza-Michael addition and ketal formation processes.