Retrosynthetic Analysis of Porantherine

A mulristrategic retrosynthetic analysis of porantherine is outlined in Section 6.2 of Part One. 

Systematic bond disconnection of porantherine [151] with recognition of the double bond-carbonyl equivalence for synthesis generated a synthetic pathway which is based on two intramolecular Mannich reactions. The symmetrical nature of the amino diketone precursor identified by the retrosynthetic analysis facilitates its preparation and subsequent transformations. Moreover, all the hetero atoms (donors) are separated by odd-numbered carbon chains and such arrangements are most amenable to normal modes of assembly. 

The synthesis of porantherine vividly illustrates the application of antithetic (retrosynthetic) analysis in developing synthetic routes to complex molecules. Systematic bond disconnection suggests structures A-F (or their equivalents) as key intermediates and also provides the overall plan of synthesis. 

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