39513-55-8Relevant articles and documents
Diversity of Intramolecular Rearrangements of Uracil Derivatives to Pyrazolones and Hydantoins Governed by a Prominent 5-Substituent Effect
Kitade, Yukio,Hirota, Kosaku,Maki, Yoshifumi
, p. 101 - 112 (2007/10/02)
Reaction of 1,3-dimethyluracil-5-carbohydrazides (4) with sodium ethoxide gave 4-ethoxycarbonyl-1,2-dihydro-3-pyrazolones (5) via a conventional intramolecular nucleophilic attack at the 6-position.In contrast, 1,3-disubstituted 5-(3-methylureido)uracil derivatives (6) were converted into the corresponding 3-methyl-5-ureidomethylenehydantoins (7) under analogous conditions.The latter rearrangement is unprecedented on account of the involvement of an initial nucleophilic attack at the 4-carbonyl carbon.The diversity of the intramolecular rearrangements of the uracil ring can be explained in terms of electronic nature of the substituent a t the 5-position.