Conformational and stereoelectronic control in ring??transformations of cis??4, 5??dialkoxytetrahydropurine??2, 6, 8??triones

N Poje, A Palković, M Poje

Index: Poje, Nevenka; Palkovic, Antun; Poje, Mirko Journal of Heterocyclic Chemistry, 1997 , vol. 34, # 2 p. 477 - 483

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Citation Number: 6

Abstract

Abstract Divergent acid-catalysed ring-openings of 4, 5-dimethoxytetrahydropurine-2, 6, 8- triones 2 at position 4, yielding 1-(5-methoxyhydantoin-5-carbonyl) ureas 4 (R 7= Me) or 5- methoxy-5-ureido-2, 4, 6-pyrimidinetriones 5 (R 7= H), can be rationalized by assuming a preference for one of two conformational isomers of the cis-fused system, associated with the N-substitution effects. Intramolecular transamidation 5→ 4 presumably occurs via a ...