Importance of steric factors in the conversion of proaporphines into aporphines. Stereochemistry of the dienone–phenol and dienol–benzene rearrangements

Abstract

Proaporphines belongong to the C-6a-(R) configuration will undergo counter-clockwise rotation of the dienone system during their acid-catalysed rearrangement to aporphines, while proaporphines of the (S) configuration will suffer a corresponding clockwise rotation; the aryl ring thus migrates from the C-13 spiro-centre to that carbon of the dienone which is syn to 6a-H.