The absolute configuration of a nitroxide spin labeled derivative of podophyllotoxin determined by the crystal structure

The crystal structure of the nitroxide spin labeled derivative of podophyllotoxin was first reported. X-ray analysis demonstrated that four contiguous chiral centers in the molecule, C1, C2, C3, and C4, adopt cis- (1:2), trans- (2:3), and cis- (3:4) arrangement.Key words: crystal structure, synthesis, nitroxyl radical, podophyllotoxin.