Synthetic studies toward akuammiline alkaloids via a biomimetic pathway

Abstract

In this chapter, initial synthetic strategy towards natural product rhazimal 2 via intermediate geissoschizine 1 is proposed, which involved Knoevenagel condensation, asymmetric 1,4 addition, and gold-catalyzed formal Pictet-Spengler cyclization. Synthetic efforts toward preparation of one of the key intermediate, α,β,γ-conjugated system 10 are demonstrated and major drawbacks of the sequence are highlighted. Alternatively, revised synthetic strategy is commenced. Its key features are represented as rigidity-dependent [3,3]-Ireland-Claisen type sigmatropic rearrangement to build direct C7-C16 bond, and later-stage functionalization to obtain unique (E)-ethylidene moiety.