Structure and conformation of 5-methoxymethyl-N4-methyl-2'-deoxycytidine

C12H19N3O5, Mr = 285.25, monoclinic, P2(1), a = 7.0180 (6), b = 8.6946 (11), c = 10.7715 (10) A, beta = 91.055 (7) degrees, V = 657.15 A3, Z = 2, Dx = 1.441 g cm-3, lambda(Cu K alpha) = 1.5418 A, mu = 9.63 cm-1, F(000) = 304, T = 287 K, R = 0.039 for 1424 observed reflections. The furanose ring adopts the C(1')-exo envelope conformation (E1), with the glycosyl linkage anti (chi = 193.8 degrees). The pseudo-rotational parameters are P = 130.9 degrees and tau m = 39.4 degrees. In the deoxyribose ring, the side chain on C(5') has the t conformation. In the pyrimidine ring the N4-methyl takes a cis conformation to N(3) and the methoxymethyl side chain is on the same side of the cytidine plane as O(4').