We report a method for the catalytic, enantioselective intermolecular addition of aliphatic amines to acyclic 1,3-dienes. In most cases, reactions proceed efficiently at or below room temperature in the presence of 5 mol % of a Pd catalyst bearing a PHOX ligand, generating allylic amines in up to 97:3 er. The presence of an electron-deficient phosphine within the ligand not only leads to a more active catalyst but also is critical for achieving high site selectivity in the transformation.

We report the direct preparation of 1,3-amino alcohols that contain up to three contiguous stereogenic centers by the umpolung coupling of imines and epoxides. Nucleophilic 2-azaallyl anions, generated from imines, are stereoselectively added to epoxides to furnish 1,3-amino alcohols after hydrolysis of the product imine. Transformations afford amino alcohols with >98% site selectivity with respect to both reaction partners and in up to >98% yield and >20:1 dr.

AbstractDiazirines are an attractive class of potential molecular tags for magnetic resonance imaging owing to their biocompatibility and ease of incorporation into a large variety of molecules. As recently reported, 15N2-diazirine can be hyperpolarized by the SABRE-SHEATH method, sustaining both singlet and magnetization states, thus offering a path to long-lived polarization storage. Herein, we show the generality of this approach by illustrating that the diazirine tag alone is sufficient for achieving excellent signal enhancements with long-lasting polarization. Our investigations reveal the critical role of Lewis basic additives, including water, on achieving SABRE-promoted hyperpolarization. The application of this strategy to a 15N2-diazirine-containing choline derivative demonstrates the potential of 15N2-diazirines as molecular imaging tags for biomedical applications.

Diazirines are an attractive class of potential molecular tags for magnetic resonance imaging owing to their biocompatibility and ease of incorporation into a large variety of molecules. In their Communication on page 12112 ff., W. S. Warren, S. J. Malcolmson, Q. Wang, and co-workers show with a 15N2-diazirine-containing choline derivative that 15N2-diazirine motifs are capable of supporting long-lasting polarization by the simple SABRE-SHEATH hyperpolarization method, making then promising as tags for NMR/MRI imaging.

AbstractDiazirines are an attractive class of potential molecular tags for magnetic resonance imaging owing to their biocompatibility and ease of incorporation into a large variety of molecules. As recently reported, 15N2-diazirine can be hyperpolarized by the SABRE-SHEATH method, sustaining both singlet and magnetization states, thus offering a path to long-lived polarization storage. Herein, we show the generality of this approach by illustrating that the diazirine tag alone is sufficient for achieving excellent signal enhancements with long-lasting polarization. Our investigations reveal the critical role of Lewis basic additives, including water, on achieving SABRE-promoted hyperpolarization. The application of this strategy to a 15N2-diazirine-containing choline derivative demonstrates the potential of 15N2-diazirines as molecular imaging tags for biomedical applications.

Diazirine sind dank ihrer Biokompatibilität und ihres leichten Einbaus in verschiedenartige Verbindungen aussichtsreiche molekulare Marker für Kernspintomographie und NMR-Spektroskopie. In ihrer Zuschrift auf S. 12280 zeigen W. S. Warren, S. J. Malcolmson, Q. Wang und Mitarbeiter anhand eines entsprechenden Cholinderivats, dass 15N2-Diazirin-Motive eine lang anhaltende Polarisation durch die einfache SABRE-SHEATH-Hyperpolarisationsmethode unterstützen.