The concise total synthesis of (±)-crinine was accomplished
in 24% overall yield and eleven steps starting from an
easily available allylic alcohol. The key step of the current synthesis
involved the NBS-promoted semipinacol rearrangement reaction of allylic
alcohols. The hydroindole skeleton with the sterically congested
quaternary carbon center was established concisely by utilizing
this semipinacol rearrangement followed by a combination of intramolecular
aldol and aza-Michael reactions.
aldol reaction - alkaloids - aza-Michael reaction - semipinacol rearrangement - total synthesis