Total Synthesis of (-)-Morphine.

Asymmetric total synthesis of (-)-morphine has been accomplished in 18 steps from commercially available 7-methoxy-2-tetralone. Our synthesis features a simple transformation from a readily prepared chiral intermediate, construction of the E-ring by acid-mediated cyclization, and singlet oxygen-mediated manipulation of the C-ring. Transformation of the final stage involves construction of the morphinan skeleton by means of 1,6-addition of in situ generated secondary amine.