Direct synthesis of 5- and 6-substituted 2-aminopyrimidines as potential non-natural nucleobase analogues†
Abstract
A series of 2-aminopyrimidine derivatives, substituted at 5- and 6-positions, were synthesized. The reaction was carried out in a single step by treatment of the corresponding β-ketoester or β-aldehydoester with guanidine hydrochloride in the presence of K2CO3, in a microwave-assisted method without the requirement of solvent. A unique 1 : 1 co-crystal structure was obtained which shows that a 6-phenyl-2-aminopyrimidinone forms a strong nucleobase-pair with cytosine, involving three hydrogen bonds. The base-pair was found to be as strong as that of natural guanine:cytosine (G:C), signifying the potential application of the synthesized derivatives. Additionally, we also report a second co-crystal involving 5-isopropyl-6-methyl-2-aminopyrimidinone and cytosine in a 1 : 1 ratio, which also shows strong base-pairing properties.