AMINOACYL NUCLEOSIDES .V. MECHANISM OF REARRANGEMENT OF N6-(ALPHA-AMINOACYL)ADENINES INTO N-(6-PURINYL)AMINO ACIDS

N6-(Glycyl-α-15N)adenine (1), on standing in water at neutral pH, loses the elements of ammonia to yield the cyclic intermediate 3H-imidazo[2,1-i]purin-8(7H)-one (2) with complete retention of the 15N. Compound 2, on warming in water, rearranges to form N-(6-purinyl)glycine (3) through an intermediate, 1-carboxymethyladenine (4). The same reaction was carried out on N6-sarcosyladenine-6-15N (15). A single product, N-(6-purinyl)sarcosine (16), containing 100% of the atom excess 15N, was obtained. On the basis of these results, a mechanism for the rearrangement of N6-(α-aminoacyl)adenines to N-(6-purinyl)amino acids is proposed. The α-amino group of 1 adds across the C6-N1 double bond, and the pyrimidine ring opens. The N1 of the purine is expelled as ammonia, and the pyrimidine ring re-forms to yield 2. After lactam opening, 2 behaves as an N1-alkyladenine, and undergoes the well-known N1→N6 rearrangement to form 3. © 1969, American Chemical Society. All rights reserved.