Straightforward and Highly Efficient Catalyst-Free One-Step Synthesis of 2-(Purin-6-yl)acetoacetic Acid Ethyl Esters, (Purin-6-yl)acetates, and 6-Methylpurines through SNAr-Based Reactions of 6-Halopurines with Ethyl Acetoacetate

A novel approach to the synthesis of purines bearing functionalized carbon substituents or methyl in position 6 was developed. Under different reaction conditions, 6-halopurine derivatives could react with ethyl acetoacetate efficiently to yield 2-(purin-6-yl)acetoacetic acid ethyl esters, (purin-6-yl)acetates and 6-methylpurines respectively. No metal catalyst and ligand were required.