A large number of complex molecules with interesting biological activities present a spirocyclic core. In recent years growing interest in building such core has led to numerous reports on the synthesis of spirocyclic derivatives. Spirocyclohexadienones are an important class of precursors for the construction of such complex structures. Moreover, the spirocyclohexadienone motif could be found in natural product. In the course of our recent work on the synthesis of α-amino vinylphosphonates through the stereoselective reduction of α-amino allenylphosphonates, we treated N-para-methoxybenzyl protected α-amino allenylphosphonates with cerium(IV) ammonium nitrate under various conditions and formed spirocyclohexadienones in good to excellent yields. This 5-endo-dig cyclization proceeds through the formation of a key iminium intermediate. A comprehensive study on the nature of the solvent used for this reaction was undertaken resulting in the formation of three types of spirodienone scaffolds. These results will be presented in this communication.

Synthesis of spirodienone lactams through 5-endo-dig cyclization of phosphorylated allenes

251st National Meeting (2016)

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