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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
Author(s) -
Eisch John J.,
Liu Wei,
Zhu Lisheng,
Rheingold Arnold L.
Publication year - 2015
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.201500917
Subject(s) - chemistry , isoindole , nucleophile , reagent , adduct , medicinal chemistry , stereochemistry , enantiomer , organic chemistry , catalysis
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.