The behaviour of 6- and 8-substituted purines toward potassium amide in liquid ammonia. A new example of tele-amination

✍ Scribed by N. J. Kos; H. C. van der Plas; A. van Veldhuizen

• Publisher: Elsevier Science
• Year: 2010
• Tongue: English
• Weight: 460 KB
• Volume: 99
• Category: Article
• ISSN: 0165-0513
• DOI: 10.1002/recl.19800990904

✦ Synopsis

Abstract

Reaction of 6‐chloro‐ and 6‐(methylthio)purine with potassium amide in liquid ammonia leads to the formation of adenine. When these aminations are carried out with ^15^N‐labelled potassium amide, the ^15^N label is found to be present in the amino group, proving that these reactions do not involve opening of the pyrimidine ring. Low temperature ^1^H‐ and ^13^C‐NMR spectroscopy of solutions of 6‐chloro‐ and 6‐(methylthio)purine in liquid ammonia, containing potassium amide give no evidence for the presence of an intermediary σ‐adduct. 8‐Chloro‐ and 8‐(methylthio)purine undergo a Tschitschibabin amination at position 6 leading to 8‐chloro‐ and 8‐(methylthio)adenine. In addition 8‐chloropurine gives adenine. Evidence is presented that the formation of this product proceeds via a tele‐amination. 6‐tert‐Butyl‐8‐(methylthio)purine and 8‐aminopurine are found to be unreactive towards potassium amide.