Syntheses and NMR, MS and X-ray investigations of homoadamantane-fused pyridopyrimidinones

✍ Scribed by Zsuzsanna Cs. Gyarmati; Péter Csomós; Gábor Bernáth; Pauliina Valtamo; Henri Kivelä; Karel D. Klika; Kalevi Pihlaja; Gyula Argay; Alajos Kálmán

• Publisher: Journal of Heterocyclic Chemistry
• Year: 2004
• Tongue: English
• Weight: 481 KB
• Volume: 41
• Category: Article
• ISSN: 0022-152X
• DOI: 10.1002/jhet.5570410208

✦ Synopsis

Abstract

The reactions of ethyl 5‐oxotricyclo[4.3.1.1^3,8^]undecane‐4‐carboxylate (2) with methyl‐substituted 2‐aminopyridines in polyphosphoric acid (PPA) gave two products, linearly‐condensed pyridopyrimidinones 4a‐c and 2‐pyridylcarboxamides 5a‐c, whereas the reactions with amino, hydroxy and nitro derivatives of 2‐aminopyridine furnished only linearly‐condensed pyridopyrimidinones (4g‐j). Use of a mixture of PPA and phosphorus oxychloride as solvent afforded both linearly‐ (4a‐c,e,f) and angularly‐condensed (6a–c,e,f) pyridopyrimidinones. In toluene, with p‐toluenesulfonic acid as catalyst, 2‐pyridylcarboxamides 5a‐f were obtained. In a mixture of PPA and phosphorus oxychloride at 80–120 °C, 5a‐f yielded angularly‐condensed pyridopyrimidinones 6a‐f. All the products exhibited characteristic features, as determined by NMR and electron ionization mass spectrometry and X‐ray crystallography.