Published as part of the Special Topic Modern Cyclization Strategies in Synthesis
Abstract
The hyrtiazepine alkaloids are a family of bisindole natural products that have the
azepinoindole backbone. We developed a biomimetic approach by constructing the azepinoindole
core in a one-pot manner through 1,4-diazabicyclo[2.2.2]octane/2,2,2-trifluoroethanol
(DABCO/TFE) promoted Pictet–Spengler reaction onto the C-4 position of tryptophan.
This strategy allowed the synthesis of common key structures of these families. The
key intermediate can be converted into the 3H-pyrano[2,3-b:5,6-e′]diindol intermediate present in hyrtimomines A and B, as well as the azepinoindole
core present in fargesine.
Key words
Pictet–Spengler reaction - indole alkaloids - azepinoindoles - biomimetic synthesis
- cyclizations - stereoselectivities
