201221-35-4Relevant academic research and scientific papers
First stereospecific total synthesis of (-)-affinisine oxindole as well as facile entry into the C(7)-diastereomeric chitosenine stereochemistry
Fonseca, German O.,Wang, Zhi-Jian,Namjoshi, Ojas A.,Deschamps, Jeffrey R.,Cook, James M.
, p. 3052 - 3056 (2015)
The first synthesis of (-)-affinisine oxindole was completed in an enantiospecific fashion from commercially available d-(+)-tryptophan in 10% overall yield. The asymmetric Pictet-Spengler reaction, diastereospecific oxidative-rearrangement of a tetrahydr
Concise Total Synthesis of (?)-Affinisine Oxindole, (+)-Isoalstonisine, (+)-Alstofoline, (?)-Macrogentine, (+)-Na-Demethylalstonisine, (?)-Alstonoxine A, and (+)-Alstonisine
Stephen, Michael Rajesh,Rahman, M. Toufiqur,Tiruveedhula, V. V. N. Phani Babu,Fonseca, German O.,Deschamps, Jeffrey R.,Cook, James M.
, p. 15805 - 15819 (2017/10/23)
A highly enantio- and diastereoselective strategy to access any member of the sarpagine/macroline family of oxindole alkaloids via internal asymmetric induction was developed from readily available d-(+)-tryptophan. At the center of this approach was the diastereospecific generation of the spiro[pyrrolidine-3,3′-oxindole] moiety at an early stage via a tert-butyl hypochlorite-promoted oxidative rearrangement of a chiral tetrahydro-β-carboline derivative. This key branching point determined the spatial configuration at the C-7 spiro center to be entirely 7R or 7S. Other key stereospecific processes were the asymmetric Pictet–Spengler reaction and Dieckmann cyclization, which were scalable to the 600 and 150 gram levels, respectively. Execution of this approach resulted in first enantiospecific total synthesis of (+)-isoalstonisine and (?)-macrogentine from the chitosenine series (7R), as well as (+)-alstonisine, (+)-alstofoline, (?)-alstonoxine A and (+)-Na-demethylalstonisine from the alstonisine series (7S).
Enantiospecific synthesis of (+)-alstonisine via a stereospecific osmylation process
Yang, Jie,Wearing, Xiangyu Z.,Le Quesne, Philip W.,Deschamps, Jeffrey R.,Cook, James M.
experimental part, p. 1431 - 1440 (2009/04/07)
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 Nb-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.
