title: The X-ray structure and absolute configuration of the anticancer drug (+)-4-ketocyclophosphamide.
abstract: 4-Ketocyclophosphamide (4-keto CP), C7H12Cl2N2O3P, monoclinic, P2(1), a = 11.909 (2), b = 10.254 (1), c = 9.873 (1) A, beta = 91.08 (1) degrees, V = 1205.45 (3) A3 Z = 4, Dc = 1.51 Mg-m-3, Cu K alpha, lambda = 1.54178 A, alpha 25 = +53.8 degrees (c = 3.0, MeOH), m.p. 107 degrees C, mu = 61.8 cm-1, F (000) = 564, R = 0.064 for 2961 observed reflexions with I greater than 1.96 sigma(I). Dextrarotatory enantiomer of 4-keto CP has S configuration at the stereogenic center. One of the two crystallographically independent molecules is disordered both in a six-membered ring and in --N(CH2CH2Cl)2 moiety. With the exception of a less populated conformer of a disordered molecule, 4-keto CP molecules adopt a conformation in which 1,3,2-oxazophosphorinane ring is in the sofa form with C(6) deviating from the plane through the remaining five ring atoms while an exocyclic N atom with its three substituents is nearly coplanar with the phosphoryl oxygen atom O(8). In a less populated conformer, the six membered ring takes the form of sofa with C(5) as a flap while an exocyclic N atom and its substituents are oriented toward the P--N(3) bond.
authors.affiliation: Faculty of Chemistry A., Mickiewicz University, Poznań, Poland.
authors.forename: M
authors.initials: M
authors.lastname: Gdaniec
authors.forename: D A
authors.initials: DA
authors.lastname: Adamiak
authors.forename: K
authors.initials: K
authors.lastname: Misiura
mesh_terms: D000970:Antineoplastic Agents / Q000737:chemistry*; D003520:Cyclophosphamide / Q000031:analogs & derivatives* / Q000737:chemistry; D008968:Molecular Conformation; D013237:Stereoisomerism; D014961:X-Ray Diffraction
chemical_list: D000970:Antineoplastic Agents; D003520:Cyclophosphamide; C008226:4-ketocyclophosphamide