THE TITLE COMPOUND [SYSTEMATIC NAME: (12R)-4,8-dimethyl-12-[(1'R)-1',2',3',4'-tetrahydro-1'-naphthyl)aminomethyl]-3,14-dioxatricyclo[9.3.0.0(2,4)]tetradec-7-en-13-one}, C(25)H(33)NO(3), was formed from the reaction of (1R)-1-amino-tetra-lin with parthenolide in methano-lic solution. X-ray crystal structure analysis determined that the configuration of the new chiral center in the title compound was R.