Polymer plicamine synthesis

The first observation in the plicamine synthesis of note is that the polymer-supported hyper-valent iodine reagent, mentioned earlier, again performed well to convert phenol 28 to spirodienone 29. Nafion-H (fluorosulfonic acid resin) catalyzed the final cyclization of 29 to form the tricyclic core of the natural product in virtually quantitative yield. After stereo- and regioselective reduction of 30 using supported borohydride, the highly hindered intermediate alcohol was methylated by... 

Scheme 21 -10 Synthesis of plicamine using polymer-supported reagents (Ley et The, etters R and s on the...

As an ultimate example of how polymer-supported reagents can be applied to alkaloid synthesis, their multiple applications in the synthesis of (+)-plicamine truly stands out (Scheme 18.17). In this synthesis, extensive use was made of parallel optimization methods in order to progress the forward route more rapidly. Again, microwave techniques worked especially well to achieve fast reaction times. The entire route, including optimization, was complete in just six weeks, without the need to rehearse the reactions using conventional solution-phase reagents or the requirement of separation methods. 

Scheme 18.17 Synthesis of (+)-plicamine using an extended array of polymer-supported reagents.

SCHEME 6.7 Synthesis of the alkaloid (+)-plicamine using polymer-supported reagents. Copyright 2006 Taylor Francis Group, LLC... 

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