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Synthesis and 1 H NMR spectra of some 1‐aryl‐2,5‐pyrrolidinediones
Author(s) -
Hubbard John L.,
Carl John M.,
Anderson Gary D.,
Rankin Gary O.
Publication year - 1992
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.5570290408
Subject(s) - chemistry , aryl , dihedral angle , steric effects , acetic anhydride , ring (chemistry) , nmr spectra database , proton nmr , computational chemistry , spectral line , organic chemistry , molecule , hydrogen bond , alkyl , physics , astronomy , catalysis
Three 1‐aryl‐2,5 pyrrolidinediones, two of which are novel, were prepared by reaction of the requisite primary aromatic amines with succinic anhydride, followed by treatment with acetic anhydride. The 1 H nmr spectra for the derivatives in which aryl is 1‐naphthyl and 1‐anthracenyl exhibit 32‐line multiplets for the four aliphatic hydrogens, indicating that all four are in different environments. Examination of molecular models demonstrates that the pyrrolidinedione and aryl ring systems cannot be coplanar and that rotation about the nitrogen‐aryl bond is restricted. Molecular mechanics calculations reveal that a dihedral angle of 50–65° for the two ring systems results in the minimum steric interaction energy.