Toward the Synthesis of Paspaline-Type Indole-Terpenes: Stereoselective Construction of Core Scaffold with Contiguous Asymmetric Quaternary Carbon Centers.

The core scaffold of paspaline-type indole-terpenes was synthesized by using the House-Meinwald rearrangement as a key step. Rearrangement of the epoxide methyl group in the precursor with methylaluminum bis(4-bromo-2,6-di-tert-butylphenoxide) as a Lewis acid proceeded smoothly to construct contiguous asymmetric quaternary carbon centers by a 1,2-chirality transfer.