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Synthesis of 3‐Substituted Dihydro‐1‐phenylamino‐1 H ‐pyrrolo[1,2‐ a ]imidazole‐2,5(3 H ,6 H )‐diones from α‐Amino Acid Phenylhydrazides and Levulinic Acid
Author(s) -
Verardo Giancarlo,
Geatti Paola,
Merli Marcello,
Castellarin Elena E.
Publication year - 2004
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.200400112
Subject(s) - chemistry , diastereomer , imidazole , levulinic acid , bicyclic molecule , stereochemistry , ring (chemistry) , medicinal chemistry , organic chemistry , catalysis
α‐Amino acid phenylhydrazides 1 readily react with levulinic acid to produce the imidazolidin‐4‐one intermediates 4 , which undergo a second ring closure to afford the dihydro‐1 H ‐pyrrolo[1,2‐ a ]imidazole‐2,5‐dione derivatives 5 . It has been established that the solvent polarity has a great influence on the rate of the second condensation reaction, but not on the first. A mechanism, supported by experimental evidence, has been proposed to explain how the imidazolidin‐4‐one intermediates 4 , obtained as expected as a mixture of two diastereoisomers, give a single isomer for the bicyclic derivatives 5 ; the absolute stereochemistry of these compounds has been determined by X‐ray crystallographic analysis. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)