ИСТИНА

We have recently disclosed a highly stereoselective and scalable method to obtain natural-like compounds containing an octahydrocyclohepta[b]pyrrole core. Herein we report an extension of this method for the preparation of octahydroindoles with various benzylic substituents at the C2-position. The 2-benzylpyrrolidine scaffold is represented in several biologically active compounds (e.g. preussin, anisomycin), therefore these compounds have attracted significant interest from synthetic chemists. In our present work, we have developed the 5-step sequence that allows us to obtain N-alkylated 2-amino-1-ethenylcyclopentanoles from cyclopentene oxide and subsequent amines with good overall yield. These compounds can be easily converted into octahydro-4H-indole-4-ones bearing miscellaneous substituents at the C2-position by varying different arylacetaldehydes, using the stereoselective aza-Cope-Mannich rearrangement. The reduction of ketogroup leads to subsequent cis-fused octahydroindoles. This methodology allows access to octahydroindole derivatives avoiding harsh conditions and expensive catalysts.