Synthesis and structural study of novel 5-aryl substituted 2-amino-4,7-dioxopyrido[2,3-d]pyrimidines

✍ Scribed by Rená Rodríguez; Margarita Suárez; Estael Ochoa; Beatriz Pita; Remberto Espinosa; Nazario Martín; Margarita Quinteiro; Carlos Seoane; Jose L. Soto

• Publisher: Journal of Heterocyclic Chemistry
• Year: 1997
• Tongue: English
• Weight: 380 KB
• Volume: 34
• Category: Article
• ISSN: 0022-152X
• DOI: 10.1002/jhet.5570340338

✦ Synopsis

Abstract

The tide compounds 4a‐c have been prepared in a one‐step procedure from 2,4‐diamino‐6‐hydroxy‐pyrimidine (1) and the corresponding arylidene substituted Meldrum's acids 2a‐e in very good yields. Semiempirical theoretical calculations (AMI) reveal two favoured conformations (A and B) for compounds 4a‐e. The ^1^H‐nmr determinations, by using Karplus and Altona equations, clearly indicate that conformation A, with the aryl group on C5 in a pseudoaxial position, is that predominant in solution. The calculated charge density values for the olefinic carbons are in agreement with the experimental push‐pull effect observed in the ^13^C‐nmr spectra.