Ring Opening of Aziridines by Pendant Silanols Allows for Stereospecific Preparations of 1'-Amino-tetrahydrofurans

We have developed a highly stereospecific cyclization of aziridine silanols into 1'-amino-tetrahydrofurans. Our protocol of stirring a substrate with 10 mol % Sc (OTf) and 1 equivalent of NaHCO in CHCl is mild and compatible with a range of activating aziridine -substituents (including tosylates, mesylates, and carbamates) and functional groups on the alkyl chains (including substituted aryl rings, alkyl bromides, and alkyl ethers). In all cases examined, di-substituted aziridine silanols give products with an configuration; conversely, di-substituted aziridine silanols give products with a configuration. While literature syntheses of 1'-amino-tetrahydrofurans exist, only one example, contemporaneous with our work, uses a similar cyclization for their construction. Control experiments demonstrate that, for this transformation, the silanol is not particularly privileged, and a variety of protecting groups on the alcohol (including other silicon protecting groups, benzyl ethers, and MOM ethers) are compatible with product formation.