The enantiospecific, stereospecific total synthesis of the ring-A oxygenated sarpagine indole alkaloids (+)-majvinine, (+)-10-methoxyaffinisine, and (+)-N(a)-methylsarpagine, as well as the total synthesis of the alstonia bisindole alkaloid macralstonidine.
The first stereospecific, enantiospecific total synthesis of the ring-A oxygenated sarpagine indole alkaloids (+)-N(a)-methylsarpagine (8), (+)-majvinine (14), and (+)-10-methoxyaffinisine (49), as well as the first total synthesis of the Alstonia bisindole alkaloid macralstonidine (9), has been accomplished. This approach employed the Schöllkopf chiral auxiliary for the stereospecific construction of the desired d-(+)-tryptophan unit required for the asymmetric Pictet-Spengler reaction. In addition, the strategy was doubly convergent for the enolate-mediated Pd(0) coupling process and the asymmetric Pictet-Spengler reaction can be employed to synthesize both macroline (2) and N(a)-methylsarpagine (8), the coupling of which provides macralstonidine (9). This approach to ring-A substituted alkoxyindole alkaloids should find wide application for the synthesis of other alkaloids for it is stereospecific and either enantiomer can be prepared with ease.
Zhao
Shuo
S
Department of Chemistry, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53201, USA.
Liao
Xuebin
X
Wang
Tao
T
Flippen-Anderson
Judith
J
Cook
James M
JM
D031051:Alstonia / Q000737:chemistry*; D002384:Catalysis; D018360:Crystallography, X-Ray; D007202:Indicators and Reagents; D026121:Indole Alkaloids / Q000737:chemistry*; D007211:Indoles / Q000138:chemical synthesis*; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D008968:Molecular Conformation; D010165:Palladium; D013237:Stereoisomerism
C467068:10-methoxyaffinisine; D007202:Indicators and Reagents; D026121:Indole Alkaloids; D007211:Indoles; C467066:N(a)-methylsarpagine; C467067:macralstonidine; C467069:majvinine; D010165:Palladium; C475809:sarpagine