Electrocyclization‐Mediated Approach to 2‐Methyltriclisine, an Unnatural Analog of the Azafluoranthene Alkaloid Triclisine

Abstract

Abstract The synthesis of 2‐methyltriclisine, an unnatural analog of the azafluoranthene alkaloid triclisine, is reported. The synthesis was achieved in 10 steps and 21 % overall yield from 2‐bromo‐3,4‐dimethoxybenzaldehyde, through the intermediacy of 3,4‐dimethoxyfluoren‐9‐one. Construction of the heterocyclic ring entailed the para ‐Claisen rearrangement of an allyl‐4‐fluorenyl ether, followed by isomerization of the resulting 2‐allylfluoren‐9‐one and a microwave‐assisted electrocyclization of the aza 6π‐electron system formed by oximation of its carbonyl function. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)