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Reactions of cyclic oxalyl compounds, 37. Substituent effects on the site of nucleophilic attack at 1 H ‐pyrrole‐2,3‐diones
Author(s) -
Kappe C. Oliver,
Terpetschnig Ewald,
Penn Gerhard,
Kollenz Gert,
Peters Karl,
Peters EvaMaria,
von Schnering Hans Georg
Publication year - 1995
Publication title -
liebigs annalen
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 0947-3440
DOI - 10.1002/jlac.199519950373
Subject(s) - chemistry , nucleophile , pyrrole , substituent , oxalyl chloride , stereochemistry , medicinal chemistry , organic chemistry , catalysis
Reactions of 1 H ‐pyrrole‐2,3‐diones 2a‐i with N‐ and O‐nucleophiles proceed by initial attack at C‐2 or/and C‐5. Consequently, earlier results suggesting structures of type A (attack at C‐3) have to be revised ( 5, 13, 17, 18b ). In general, electron‐withdrawing substituents at C‐4 favor attack at C‐5 with formation of 2‐pyrrolones 5, 6, 10, 13, 17 , and 20 . Alternatively, attack at C‐2 leads to α‐oxobutenoic acid derivatives 3, 7, 11, 12, 15 , and 18 . IR and 13 C‐NMR spectroscopic techniques were employed to differentiate between the possible isomeric addition products formed. The structure of methyl α‐oxobutenoate 15 was established by an X‐ray crystallo‐graphic analysis.