Stereoselective Synthesis of Novel (±)-trans-Dihydronarciclasine Analogues: Preparation of a Pivotal Intermediate Containing Two Methoxy Substituents

An efficient stereoselective synthesis of a pivotal intermediate, a cyclic allyl alcohol derivative containing two methoxy groups [(±)-22], using for the preparation of (±)-trans-dihydronarciclasine analogues was elaborated starting from easily available and inexpensive methyl gallate. This new synthetic route consists of 17 reaction steps, and provides an opportunity to obtain the wanted alkaloid derivative containing an additional methoxy group at position 11, in the ring A of the phenanthridone scaffold.