Abstract
A new method is reported for the preparation of indolo[2,3-a]quinolizidines based on radical cyclization of a 2-acyl-1-phenylthiotetrahydro-β-carboline bearing a pendent α,β-unsaturated ester. The required radical cyclization precursor is efficiently assembled from E-5-ethoxycarbonyl-4-pentenoic acid and 3,4-dihydro-β-carboline through a DCC/HOBt-activation/N-acylation and BF3·Et2O/PhSH iminium-ion trapping sequence. Tin-mediated radical cyclization of the radical cyclization precursor affords stereoselectively a cis-lactam (dr = 7:1) in good yield (81%), bearing the correct D/E ring fusion stereochemistry for the Tacaman alkaloids. The methodology has been applied to formal syntheses of the indoloquinolizidine alkaloids, (±)-eburnaminol and (±)-larutensine.
Original language | English (US) |
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Pages (from-to) | 6342-6346 |
Number of pages | 5 |
Journal | Tetrahedron Letters |
Volume | 50 |
Issue number | 46 |
DOIs | |
State | Published - Nov 18 2009 |
Externally published | Yes |
ASJC Scopus subject areas
- Biochemistry
- Drug Discovery
- Organic Chemistry