Synthesis of Vinca Alkaloids and Related Compounds, XXXIV: Synthesis of (3S,14S,16S)-Bromovincamines and Bromoapovincamines by Regioselective Bromination

Article abstract of DOI:10.1002/ardp.19873200904

By bromimation of the iminium salt 2a (X=Cl), the 9-bromo derivative 2c (X=ClO4) is obtained in isomer-free state.Bromination of the lactam 8d leads to ca. 7.5:1 mixture of 11-bromo (8c) and 9-bromo (8a) lactams.These precursors have been used to synthesize 9-, 10- and 11-bromovincamines (11a-c), and 9-, 10- and 11-bromoapovincamines (12a-c).