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Ambident anion chemistry: The reaction of sterically‐hindered phenolate anions with 1 H ‐pyrrole‐2,5‐diones
Author(s) -
Pastor Stephen D.,
Hessell Edward T.
Publication year - 1988
Publication title -
journal of heterocyclic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.321
H-Index - 59
eISSN - 1943-5193
pISSN - 0022-152X
DOI - 10.1002/jhet.5570250320
Subject(s) - chemistry , medicinal chemistry , tetrahydrofuran , maleimide , yield (engineering) , dimer , solvent , steric effects , alkyl , benzyl alcohol , substituent , alcohol , inorganic chemistry , polymer chemistry , organic chemistry , catalysis , materials science , metallurgy
The reaction of N ‐phenylmaleimide, 4a , with sodium 2,6‐di‐ t ‐butylphenolate, 5a , in dimethylsulfoxide (DMSO) resulted a complex oligomeric mixture. The dimer 8 was isolated from the reaction of the N ‐alkyl‐maleimide 4b with 5a in DMSO. The reaction of 4a with 5a in tetrahydrofuran (THF), which is an aprotic solvent that is known to promote ion pairing, resulted in the isolation of a low yield of 6a . The reaction of 4a with 5a in the hydrogen‐bonding solvent t ‐butyl alcohol gave 6a in slightly higher yield. The N ‐alkylpyrrolidine‐2,5‐diones 6c‐f were obtained by the reaction of the maleimides 4c‐e with the corresponding sodium phenolate 5a‐b in t ‐butyl alcohol reaction medium. The isolated yield of product increased with the size of the N ‐alkyl substituent of the maleimide. Surprisingly, the reaction of the 2,6‐dimethylphenolate 5c with 4d led to the isolation of the dimer 10 with the formation of a quaternary carbon atom. The yield of 6a was observed to counterion dependent, increasing in the order Na + < Li + < MgBr + in t ‐butyl alcohol. The bismaleimides 12 and 14 were obtained by the reaction of either 11 or 13 with 5d in THF.