Stereocontrolled Synthesis of 1,3-Diamino-2-ols by Aminohydroxylation of Bicyclic Methylene-Aziridines

Nitrogen‐containing stereotriads, which are defined as compounds with three adjacent stereodefined carbon atoms, are common structural motifs in several biologically relevant compounds. The 1,3‐diamino‐2‐ol motif in particular is an important pharmacophore for which there are limited stereoselective synthetic approaches. In this communication, we describe the aminohydroxylation of a series of bicyclic methylene‐aziridines obtained from the aziridination of a series of homoallenic carbamates. The unusual electronic and steric features of these useful heterocyclic scaffolds render the Os‐catalyzed aminohydroxylation of the exocyclic alkene highly regio‐ and stereoselective. Rearrangement of the proposed N,O‐aminal intermediate to a 1,3‐diamino‐2‐one is followed by reduction with NaBH4 to deliver the desired 1,3‐diamino‐2‐ols in good yields with high diastereomeric ratios. Complex amine‐containing stereotriads are recurring motifs in a number of bioactive and pharmacologically important molecules. The regio‐ and stereocontrolled aminohydroxylation of bicyclic methylene‐aziridines can be followed by carbonyl reduction to deliver 1,3‐diamino‐2‐ols in good yields with good diastereoselectivities (Ts = para‐tolylsulfonyl, Bs = phenylsulfonyl, Boc = tert‐butoxycarbonyl).