Enantiospecific synthesis of (+)-alstonisine via a stereospecific osmylation process.
The first enantiospecific total synthesis of (+)-alstonisine has been accomplished from D-tryptophan methyl ester 13 in 12% overall yield (in 17 reaction vessels). A diastereospecific osmylation process has been employed as a key step to convert indole 18 into spirocyclic oxindole 19. Mechanistic studies of the stereoselective osmylation of the 2,3-indole double bond of indole alkaloids has been carried out. Compelling evidence for the intramolecular delivery of OsO4 via N b-complexation was obtained for the osmylation process. The correct structure of (+)-alstonisine (1) was determined by NOE spectroscopic experiments and further confirmed by single-crystal X-ray analysis.
Yang
Jie
J
Department of Chemistry, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53201, USA.
Wearing
Xiangyu Z
XZ
Le Quesne
Philip W
PW
Deschamps
Jeffrey R
JR
Cook
James M
JM
D000470:Alkaloids / Q000138:chemical synthesis* / Q000737:chemistry; D018360:Crystallography, X-Ray; D007211:Indoles / Q000138:chemical synthesis* / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D000078183:Oxindoles; D013141:Spiro Compounds; D013237:Stereoisomerism
D000470:Alkaloids; D007211:Indoles; D000078183:Oxindoles; D013141:Spiro Compounds; C470641:alstonisine