The snytheses and reactivity of an unusual class of heterocycles, the 1,4-diazaspiro[2.2]pentanes (DASPs), will be discussed.  Several approaches were explored to effectively prepare these molecules with high levels of chemo-, regio-, and diastereocontrol, thus enabling their use as reactive intermediates for the flexible preparation of nitrogen-containing stereotriads.  Inter/inter-, intra/intra-, and intra/intermolecular bis-aziridinations were investigated and the intra/intermolecular approach was the most useful for differentiating the electronics of the two aziridines based on the identity of the nitrogen �protecting groups�.  The reactivity of the DASPs were explored in terms of selective ring opening at both C1 and C3  positions of the original allene.  Assessible motifs include N,N-aminals, vicinal diamines, triamines, and azetidines depending on the structure of the allene and the reaction conditions employed.  Also, rearrangement and ring contraction of N,N-aminals to 1,3-diaminoketones will be discussed.

Synthesis of 1,4-diazaspiro[2.2]pentanes as reactive intermediates for the rapid preparation of novel stereotriads

243rd National Meeting (2012)

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