“…3'-0-Acetyl-5'-0-[[bis(2,2-dimethyl-l-aziridinyl)phosphinyl]carbamoyl]thymidine (6). The preparation of this compound from 3'-O-acetylthymid ine18 was analogous to that of its isomer 5, except that the final product was crystallized from chloroform/hexane to give 0.380 g (70%) of 6 as white plates: mp 141-143 °C; NMR (CDC13) 1.43 (s, 12 H, aziridine CH3), 1.82 (s, 3 H, C5-CH3), 2.1 (s, 3 H, acetyl), 2.30 (d, 4 H, aziridine CH2, JPli = 14 Hz), 2.2 (m, 2 H, 2'-H), 4.23 (br s, 1 H, 3'-H), 4.38 (br s, 2 H, 5'-H), 5.33 (br, 1 H, 4'-H), 6.43 (t, 1 H, l'-H), 7.43 (s, 1 H, C6-H), 8.45 (br d, 1 H, carbamate N-H), 10.58 (br, 1 H, N3-H).…”