Glycosylidene Carbenes. Part 20. Synthesis of deprotected, spiro‐linked C ‐glycosides of C 60

Mannosylidenation of buckminsterfullerene (C 60 ; 1 ) with the 2,3‐di‐ O ‐benzyl‐4,6‐ O ‐benzylidene‐protected diazirine 7 and the 2,3:4,6‐di‐ O ‐isopropylidene‐protected diazirine 8 leads to the spiro‐linked C ‐glycosides 6 and 10 in 44 and 31% yield, respectively ( Scheme ). The diazirine 8 was prepared in five steps from 2,3:4,6‐di‐ O ‐iso‐propylidene‐α‐ D ‐mannopyranose ( 11 ) via the oximes 12 , the ( Z )‐hydroximolactone 13 , the mesylate 14 , and the diaziridines 15 . Deprotection of the mannosylidenated fullerenes 6 and 10 under acidic conditions gave the partially deprotected diol 9 (97%) and the unprotected mannosylidenated fullerene 16 (73%), respectively. The mannosylidene‐fullerenes 6, 9, 10 , and 16 possess a 6–6 ring‐bridged σ‐homoaromatic structure.