The cyclization of N6‐(ω‐hydroxyalkyl)adenines with a N6H‐group leads to N6,N1 ring closure regardless of the method of the cyclization that was used. Five‐membered to eight‐membered rings were obtained using NBS/PPh3; however, under Mitsunobu conditions, the eight‐membered fused purine was not formed. Surprisingly, the cyclization of N6‐methyl‐N6‐(4‐hydroxybutyl)adenine only leads to N6,N7 ring closure
(R)‐3‐(2′‐hydroxyprop‐1‐yl) adenine 4 was obtained by alkylation of adenine 1 with R‐propylene carbonate 2 in the presence of pulverized sodium hydroxide in the synthetic process of tenofovir. The elucidation of the structure of 4 was confirmed by single crystal X‐ray diffraction and NMR experiments such as 1D 1H, 13C, and DEPT, as well as 2D COSY, HSQC, and HMBC spectra.