Facile Rearrangement of the 6,11‐Diphenyldibenzo[ b , f ][1,4]diazocine Skeleton into a Substituted 2‐(2‐Aminophenyl)‐1,3‐diphenylisoindole via Anomalous Carbolithiation or Hydrolithiation: Corroboration of Operative SET Processes

The starting 6,11‐diphenyldibenzo[ b , f ][1,4]diazocine has been individually treated with R–Li reagents in THF, where R = AlH 4 , PhCH 2 , Ph 2 CH, Ph 3 C, CH 3 , CH 3 (CH 2 ) 3 , C 6 H 5 or Ph–C≡C, to learn whether an expected 1,2‐ or 1,4‐addition would cleanly occur. Contrary to such an assumption based on nucleophilic attack, this [1,4]diazocine with PhCH 2 Li yielded only the enantiomers of (4b,11 R )‐11‐benzyl‐4b,11‐diphenyl‐4b,11‐dihydro‐5 H ‐benzo[4,5]imidazo[2,1‐ a ]isoindole; with Ph 2 CHLi yielded 2‐[1‐(4‐benzhydrylphenyl)‐phenyl‐2 H ‐isoindol‐2‐yl]analine; and with LiAlH 4 2‐(2‐aminophenyl)‐1,3‐diphenylisoindole. Finally, individual reactions of the [1,4]diazocine with CH 3 Li, n BuLi or PhLi gave 4–5 inseparable products, instead of any simple 1,2 or 1,4 adduct. The anomalous carbolithiations and hydrolithiation observed are irreconcilable with a nucleophilic mechanism but in excellent accord with a SET radical‐anion pathway.