Functional group interconversion retro-synthetic

Retro-synthetic analyses ( = "antitheses") of relatively simple, but non-commercial target molecules are described. Stepwise disconnections and functional group interconversions are used to transform the desired molecule into inexpensive commercial compounds. 

The construction of a synthetic tree by working backward from the target molecule (TM) is called retro synthetic analysis or antithesis. The symbol ==> signifies a reverse synthetic step and is called a transform. The main transforms are disconnections, or cleavage of C-C bonds, md functional group interconversions (FGI). 

The retro synthetic pathway is outlined in Scheme 49 and starts with the simplification of the TAN1251A again to the known intermediate 119, whose first conversion into the alkaloid had been reported by the same authors [63], The target compound 119, in turn, can be prepared from 126 also following their known protocol. Compound 126 should be obtained from 156 via installation of an azide group and A-alkylation. Disassembly of the cyclohexanone ring from 156 in a retrosynthetic sense leads to keto aldehyde 155, which may be prepared by alkylation of proline 154 followed by some functional group interconversion steps. 

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